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Best treatments for type 2 diabetes

We compare the safety, effectiveness, and price of the most common drugs for this condition

Published: December 2012


Six classes of oral medicines (and 12 individual drugs) are now available to help the 25.8 million people in the U.S. with type 2 diabetes control their blood sugar when diet and lifestyle changes are not enough. Our evaluation of these medicines found the following:

  • Newer drugs are no better. Two drugs from a class called the sulfonylureas and a drug named metformin have been around for more than a decade and work just as well as newer medicines. Indeed, several of the newer drugs, such as Januvia and Onglyza, are less effective than the older medications.
  • Newer drugs are no safer. All diabetes pills have the potential to cause adverse effects, both minor and serious. The drugs’ safety and side effect “profiles” may be the most important factor in your choice.
  • The newer drugs are more expensive. The newer diabetes medicines cost many times more than the older drugs.
  • Taking more than one diabetes drug is often necessary. Many people with diabetes do not get enough blood sugar control from one medicine. Two or more may be necessary. However, taking more than one diabetes drug raises the risk of adverse effects and increases costs.

Taking effectiveness, safety, adverse effects, dosing, and cost into consideration, we have chosen the following as Consumer Reports Best Buy Drugs if your doctor and you have decided that you need medicine to control your diabetes:

  • Metformin and Metformin Sustained-Release — alone or with glipizide or glimepiride
  • Glipizide and Glipizide Sustained-Release — alone or with metformin
  • Glimepiride — alone or with metformin

These medicines are available as low-cost generics, costing from $4 to $35 a month. If you have been diagnosed with diabetes, we recommend that you try metformin first unless it's inappropriate for your health status.

If metformin fails to bring your blood sugar into normal range, we recommend you add glipizide or glimepiride.


Type 2 diabetes is one of the most serious medical conditions affecting our nation today. The number of people who have it has been rising alarmingly.

Type 2 diabetes used to be referred to as “adult onset” diabetes, but no longer. In recent years, the incidence among children and adolescents has exploded. Much of that surge is due to the dramatic increase in the last 20 years in the number of young people who are physically inactive and overweight or obese.

The statistics are sobering. An estimated 25.8 million people in the U.S., or about 8 percent of the population, have diabetes. That’s up from 2.5 percent of the population in 1980. Despite the increase of the disease among the young, older people are still the largest age group affected with nearly 11 million people 65 or older afflicted with diabetes. And about 1.9 million adults are newly diagnosed with type 2 diabetes every year.

But despite widespread attention to the diabetes epidemic, about one in three people who have diabetes — some 7 million people — have not been diagnosed and do not know they have it. And many of those who have been diagnosed are not getting adequate treatment. A quarter to a third of the people who have been diagnosed with diabetes fail to receive the medical care and medicines that research has shown to be effective.

Why is diabetes of such concern? For starters, diabetes more than doubles the risk of developing and dying of heart disease and other problems. Indeed, the condition is as potent a predictor and risk factor for heart disease and heart attack as are cigarette smoking, high blood pressure, and high cholesterol. In 2004, the latest year for which data is available, heart disease was a factor listed on 68 percent of diabetes-related death certificates among people 65 or older.

Diabetes also significantly raises the risk of a host of other problems. These include: stroke, nerve damage, kidney damage; damage to the eye as well as total blindness; impotence, poor wound healing, and susceptibility to infections that can worsen and require amputations of toes, feet, or part of a leg.

In addition, people with diabetes are very likely to have other dangerous health conditions. One study found that 47 percent of people with diabetes had two other heart disease risk factors (such as smoking, high blood pressure, and high cholesterol), and 18 percent had three or more.

Overall, diabetes is the seventh leading cause of death in the United States. It is also a leading cause of disability. Women have the same prevalence of diabetes as men, but they are much more likely to die from it. African-Americans, Asian-Americans, Hispanics, American Indians, and the indigenous people of Alaska are more prone to develop diabetes (due to genetic and environmental factors) and to become disabled or die from it (due to multiple factors, including that they are less likely to get good care).

But proper treatment can keep people with diabetes healthy. In fact, all people with diabetes who receive proper and consistent care live a normal life, and can work and carry out daily activities.

Symptoms and getting tested

The symptoms of type 2 diabetes tend to develop gradually over time and include:

  • Fatigue
  • Blurred vision
  • Frequent urination
  • Numbness or tingling in your hands or feet
  • Increased thirst and hunger
  • Infections and slow healing of wounds

These symptoms can also be mild and/or intermittent for years. If you experience any of these — and especially if you experience two or more, for even a few days — you should see a doctor.

In the early stages of the disease, symptoms may be nonexistent. That’s unfortunate because the damage to organs occurs even in the absence of symptoms. For this reason, it’s important for people who may be at risk for diabetes to get their blood sugar levels checked regularly. Those at risk include:

  • People 65 and older
  • People who have a condition called metabolic syndrome
  • People who are overweight or obese
  • Anyone with a parent or a sibling who has diabetes
  • People who are African-Americans, Hispanic-Americans, Asian-Americans, Native Americans, Pacific Islanders, or Alaskan Natives
  • Women who have had diabetes during pregnancy or a baby weighing more than 9 pounds at birth

If you are in one of these groups and have never had a blood sugar check, get it tested as soon as possible.

There is a disagreement in the medical community about whether all adults should have their blood sugar checked periodically. The American Diabetes Association advises that everyone aged 45 and over have a blood sugar test once every three years. But the highly regarded U.S. Preventive Services Task Force says not enough scientific evidence exists to show that such broad screening has benefits or is worth the cost.

We think the decision rests with you and your doctor, and depends on an assessment of your overall health, risk factors, weight, and family history. Some doctors are inclined to check the blood sugar levels of most people over age 45 or 50, especially if they are 10 or more pounds overweight. Other doctors may be more conservative.

Blood sugar tests are inexpensive and easy, though they may have to be done a few times to yield a conclusive diagnosis. One type of test is done after an overnight fast. If your blood sugar is 126 milligrams per deciliter (mg/dl) or greater after being checked on two or three different occasions, you are considered to have diabetes. Another type of test can be done at any time (not just after an overnight fast). If this test indicates your blood sugar level is 200 mg/dl or above, you are considered to have diabetes.

Your doctor may also talk to you about a blood test known as “hemoglobin A1c” (pronounced hemoglobin “A,” “one,” “c”; usually abbreviated in print as HbA1c and often referred to by diabetes patients as “my A1c”). This is a commonly used test to evaluate blood sugar control after treatment is started. But your doctor may order this test to make the diagnosis in the first place. There’s more about this measure in the next section.

Type 1 vs. type 2 diabetes

Diabetes is a disease characterized by elevation of blood glucose (a sugar) caused by decreased production of the hormone insulin and/or increased resistance to the action of insulin by certain cells. Glucose is the body’s main fuel. When you eat carbohydrates (pasta, bread, rice, grains, fruits, and vegetables), your digestive system breaks them down into glucose, which is released into the bloodstream so your body can use it for energy. Glucose also gets stored in the liver as glycogen, which can later be broken down back into glucose when the body needs fuel.

Insulin, which is produced in the pancreas, regulates both the movement of glucose into the body’s cells and the breakdown in the liver of glycogen into glucose. Both actions are critical to keeping blood sugar levels within normal ranges.

Type 1 diabetes affects about 1.5 to 2 million people in the U.S. In this condition—usually diagnosed in childhood or the early teen years—the pancreas, over a relatively brief period of time, stops producing insulin altogether. The onset of the disease is usually abrupt, with severe symptoms that require immediate attention. Type 1 diabetes is an “autoimmune” disease, which means the body attacks itself. Specifically, aberrant immune cells damage and destroy the part of the pancreas that produces insulin. People with type 1 diabetes must inject insulin every day.

Type 2 diabetes, the pancreas produces enough insulin, at least in the early years of the disease. But for reasons that are still not well understood, the body’s cells become resistant or insensitive to it. To compensate, the pancreas pumps out increasing amounts of insulin to normalize blood glucose levels. Over time — as long as a decade — this ever-increasing production becomes unsustainable, and the pancreas’ ability to produce insulin declines.

As a result, the telltale marker — and problem — of diabetes emerges: glucose levels rise in the blood because it is unable to enter the body’s cells. The excess glucose is damaging to the body’s tissue and leads to the symptoms and complications of diabetes. When the blood glucose level gets high enough, the sugar begins to appear in the urine and causes increased urination.

Elevated blood sugar puts a strain on almost every organ and other parts of the body. Over years, it is particularly toxic to the body’s blood vessels; it causes them to thicken. This leads to problems in the eyes and kidneys, the heart, the liver, and the blood circulation system. High blood sugar also damages the nerves. Proper treatment that keeps blood sugar in the normal range sharply reduces the risk of these complications.

Again, there are many theories and ideas about the causes of type 2 diabetes, and the insulin resistance that characterizes it. Studies show the disease runs in families, meaning it has a strong genetic (hereditary) component. Another cause is being overweight or obese. In some cases, this can occur due to a genetic propensity, but in most cases it is due to overeating and lack of exercise. About 55 percent of people diagnosed with diabetes in the U.S. are overweight or obese.

While recent media attention surrounding the diabetes epidemic has focused on its link to obesity, the statistic above shows that 45 percent of people with diabetes are not overweight, meaning that there are other causes of the disorder.

What is pre-diabetes?

In the last decade, doctors and researchers have recognized that a large number of people in the U.S. have fasting blood sugar levels that are above 110 mg/dl (the upper limit of normal) but less than the 126 mg/dl required for a diagnosis of diabetes. The most recent estimate from the Centers for Disease Control and Prevention indicates that 35 percent of adults 20 and older — 79 million people — have blood glucose levels in this range and thus have what is called pre-diabetes. (It’s also sometimes called borderline diabetes or impaired fasting glucose.)

What concerns doctors is that a growing body of research now shows that people with pre-diabetes have (a) a very high risk of developing diabetes, and (b) an elevated risk of heart disease and stroke even if their glucose level never rises above 126 mg/dl.

In an analysis involving 10,428 people in Australia, those with pre-diabetes were found to have 2.5 times the risk of dying from heart disease over a 5-year period compared to people whose blood sugar was normal.

Such findings are leading many doctors to consider drug treatment for people with pre-diabetes. But most doctors agree, and research backs it up, that dietary and lifestyle changes can be very effective for keeping pre-diabetes under control — before any medicines need to be prescribed.

That said, this report does not specifically address treatment of pre-diabetes. If you are diagnosed with pre-diabetes we would urge you to talk with your doctor about ways to alter your diet and lifestyle, and lose weight if you need to.

Lifestyle modifications have also become a mainstay of treatment for people with diabetes. Studies consistently show that lifestyle changes alone — especially weight loss in those who are overweight or obese — can prevent the complications of diabetes. For some people, these changes can eliminate or reduce the need for drugs. The next section discusses this further, and you can also find more detailed information about lifestyle changes in our free diabetes patient power toolkit.

Since many people with diabetes also have high blood pressure and/or high cholesterol, your doctor will aim to get those under control, too, using diet and lifestyle changes, and medicines if necessary.

Medication basics

Oral diabetes medicines—pills you take by mouth—are just one treatment among several that doctors use to help keep people with diabetes healthy. But they are a critical part of treatment.

This report focuses on six classes of pills. We evaluate and compare the drugs in all six groups. We do not evaluate injectable drugs, including the newest ones, exenatide (Byetta) and liraglutide (Victoza). We also don’t compare diabetes pills with treatment with insulin or combination treatments consisting of injectable drugs.

Note that even though most people prefer to avoid injections, insulin and other injectable diabetes drugs often become necessary if diet, exercise, and pills fail to keep blood sugar under control.

Like all drugs, the names of the six diabetes drug groups and the names of the individual medicines in those groups are not easy to pronounce or remember. We do our best in this report to keep things simple but unfortunately we can’t avoid using these complex names.

There are two tables below - one presents the groups of diabetes drugs, including those now available in combination form, and the other presents the individual drugs with their generic and brand names. We indicate whether the class has a generic available and whether an individual drug is available in generic form. Generics are much less expensive.

Type of Drug

Individual Drugs (Brand and generic names)

Available as a Generic?


Brands: Amaryl, Diabeta, Glynase, Glucotrol, Glucotrol XL

Generics: Glimepiride, Glipizide, Glyburide


Brands: Glucophage, Glucophage XR

Generics: Metformin


Brands: Actos, Avandia

Generics: Pioglitazone

Yes for Actos
Alpha-glucosidase inhibitors

Brands: Precose, Glyset

Generics: Acarbose


Brands: Prandin, Starlix

Generics: Nateglinide

Dipeptidyl peptidase 4 inhibitors Januvia, Onglyza No
Combinations of sulfonylureas plus metformin

Brands: Glucovance

Generics: known by generic names of the two drugs

Other Combinations Actoplus Met, Avandaryl, Avandamet, Duetact, Janumet, Kombiglyze XR No

The six types of diabetes medicines work in different ways. But they all: (a) lower blood sugar levels, (b) help improve the body’s use of glucose, and (c) decrease the symptoms of high blood sugar.

The complexity of the way the different diabetes drugs work defies simple explanation. But it’s useful to know the basics.

  • The sulfonylureas and meglitinides increase the secretion of insulin by the pancreas.
  • Metformin inhibits glucose production by the liver and decreases insulin resistance.
  • The alpha-glucosidase inhibitors delay absorption of glucose by the intestine.
  • The thiazolidinediones decrease insulin resistance.
  • The dipeptidyl peptidase 4 inhibitors (Januvia and Onglyza) promote the release of insulin from the pancreas after eating a meal.

Since the drugs work in different ways, they are sometimes used in combination to enhance the effectiveness of treatment. Indeed, more than 50 percent of people with diabetes who start taking one type of medicine will need another type (or insulin) within three years to keep their blood sugar under control. But all will also need to alter their diets and lifestyles as well — losing weight if needed, making dietary changes (such as cutting back on carbohydrates), quitting smoking, and becoming more physically active.

Evidence strongly supports the additive effect of lifestyle changes plus medicines. But several studies also show that many people with diabetes can lower their blood sugar levels almost as much with lifestyle changes alone as with medicines, especially in the early stages of their disease.

Generic Name

Brand Name (s)

Available as a Generic?

Pioglitazone Actos Yes
Rosiglitazone Avandia No
Repaglinide Prandin No
Nateglinide Starlix Yes
Alpha-glucosidase Inhibitors    
Acarbose Precose Yes
Miglitol Glyset No
Metformin Glucophage, Glucophage XR* Yes
Glyburide/ glibenclamide Diabeta, Glynase Yes
Glipizide Glucotrol, Glucotrol XL* Yes
Glimepiride Amaryl Yes
Dipeptidyl peptidase 4 inhibitors    
Sitagliptin Januvia No
Saxagliptin Onglyza No

*XR=extended release, XL=long-acting

Our evaluation of diabetes drugs is based largely on a thorough, independent review of the scientific research on diabetes drugs. One hundred and sixty-six studies were closely examined out of thousands screened. The review was conducted in 2010 by a team of physician researchers at the Johns Hopkins University Evidence-based Practice Center. This team conducted the review as part of the Effective Health Care Program sponsored by the Agency for Healthcare Research and Quality, a federal agency. See the full report here. Additional sources were used to update this review, as well as an analysis of selected classes of diabetes drugs conducted by the Drug Effectiveness Review Project (DERP) based at Oregon Health & Science University.

Neither the Johns Hopkins University Evidence-based Practice Center, the Agency for Healthcare Research and Quality, nor DERP are in any way responsible for the advice and recommendations in this report. These entities also played no role in selecting our Best Buy drugs; Consumer Reports Best Buy Drugs is solely responsible for those.

Treatment goals

Given that all the diabetes drugs have the potential to cause side effects and lifestyle changes have benefits to your health beyond controlling blood sugar, most doctors will recommend you try diet and lifestyle modifications first — before you try a drug.

Many people with diabetes, however, also have high blood pressure and/or elevated cholesterol, or have been diagnosed with coronary artery or vascular disease. If you are in this category, your doctor may prescribe a diabetes drug when you are diagnosed, along with diet and lifestyle changes and classes in diabetes self-management.

Indeed, so many people with diabetes have other conditions and heart disease risk factors that doctors commonly treat them as “multi-disease” patients whose care and various medications must be managed particularly closely. Because heart disease risk factors, including diabetes, take a cumulative toll, medical groups and physician organizations have set aggressive goals for people with diabetes who have multiple conditions. Table 1 below presents these.

The aim of treatment with lifestyle changes and medications is to get your HbA1c lower (and keep it low) and to reduce your symptoms. As mentioned already, the HbA1c test is the one your doctor will use to track treatment success (or failure). It measures glucose levels chemically bound to hemoglobin, a protein carried by red blood cells. Over time, high blood sugar levels cause more glucose to bind with hemoglobin, so a high HbA1c percentage indicates that blood sugar levels are high on average.

Many experts believe that an HbA1c level below 7 percent is associated with a lower risk of diabetes complications, such as kidney disease and eye disease that can lead to blindness. However, there is no definite proof that maintaining HbA1c below 7 percent helps prevent heart disease and premature death because most studies of the oral diabetes drugs have only looked at the affects on HbA1c for a year or less.

Although aiming for an even lower HbA1c level — below 6.5 percent — that’s closer to the range found in healthy people who don’t have diabetes has been promoted in the past, it’s now unclear whether that is better for most diabetes patients. In the largest, most well-regarded study of this issue, people with diabetes who achieved an average HbA1c level of 6.4 percent over 3.5 years had an increased risk of death and no reduction in heart attacks or deaths from heart disease compared with patients whose HbA1c was maintained at 7.5 percent.

Table 1. Goals for People with Diabetes


Recommended Goal

Blood Sugar*  
Fasting blood glucose 70-130 mg/dL
Post-meal (2-hour) blood glucose Below 180 mg/dL
Hemoglobin A1c (HbA1c) Below 7.0%
Total cholesterol Below 200 mg/dL
LDL (“bad”) cholesterol Below 100 mg/dL
HDL (“good”) cholesterol Above 40 mg/dL for men and 50 mg/dL for women
Triglycerides Below 150 mg/dL
Blood pressure Below 130/80 mmHg

* These goals may be individualized based on your specific health situation and circumstances.

Sources: American Diabetes Association; American Association of Clinical Endocrinologists; International Diabetes Federation; National Cholesterol Education Program; Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure; recent studies.

Definitions: LDL= low-density lipoprotein cholesterol; HDL= high-density lipoprotein cholesterol; mg = milligrams; dl=deciliter of blood; mmHg = millimeters mercury.

Two other studies did not find an increased risk of death in patients who maintained their HbA1c below 6.5 percent. But these studies were consistent with the one described just above in that they also failed to show a reduction in cardiovascular events (like a heart attack) or deaths.

Given these results and the evolving science, the American Diabetes Association and other diabetes experts now recommend keeping HbA1c around or below 7 percent for most patients, but not below 6.5 percent. Also, a higher HbA1c goal may be appropriate for certain patients, including those with a history of repeated episodes of low blood sugar, coronary heart disease, stroke or limited life expectancies.

Managing diabetes is complex because it requires care ful, sometimes daily attention to diet, monitoring blood sugars, and sometimes frequent adjustment of medication doses. It is also very important to get regular foot and eye exams, and, if necessary, treatment for high blood pressure and cholesterol — all of which are proven methods to reduce complications of diabetes.

A formal program or a conscientious primary care doctor can help you manage diabetes appropriately.

Safety and side effects

All the diabetes medicines can have side effects. These vary from drug class to drug class and medicine to medicine. Generally, the risks posed by diabetes drugs are not an impediment to using them if you truly need one.

Even so, side effects can keep people from taking their diabetes pills. On average, 10 to 20 percent of people with diabetes stop taking their pills due to side effects. It's important to discuss any side effects you experience with your doctor.

Side Effects of Oral Diabetes Drugs

Most of the side effects listed here ease over time or stop when the medication is discontinued. However, a few can be permanent in certain people


  • Hypoglycemia or low blood sugar (usually minor if caught in time but can be serious or fatal if not treated; symptoms include profuse sweating, tremor, shakiness, dizziness, hunger. When serious, includes mental confusion, coma, and risk of stroke or death)
  • Weight gain
  • Gastrointestinal side effects (abdominal pain, nausea, vomiting, diarrhea, gassiness, and bloating)
  • Edema (fluid in legs and ankles)
  • Increase in “bad” cholesterol (LDL)


  • Congestive heart failure
  • Anemia (low red blood cell counts)
  • Allergic reactions

Very Rare

  • Thrombocytopenia (low blood platelet counts)
  • Lactic acidosis (build up of acid in the blood)
  • Leukopenia (low white blood cell counts)
  • Macular edema (eye problems)
  • Liver disease/liver failure

Most notably, some diabetes drugs can cause low blood sugar, or hypoglycemia. This is a dangerous side effect and one that leads some doctors to prescribe one diabetes drug over another. The symptoms of hypoglycemia are listed in the box above. Unfortunately, some people do not have minor symptoms to warn them that their blood sugar is getting dangerously low. That’s one reason your doctor will emphasize to you that you must check your blood sugar regularly.

Another worrisome side effect of some of the diabetes drugs is weight gain, or difficulty losing weight. Since many people with diabetes are trying to lose weight, this side effect can also be very frustrating.

Drug effectiveness and safety

The good news is that the diabetes drugs have been compared to each other in many high-quality studies, and some of the drugs have been used for years and helped millions of people. The bad news is that most of the careful studies have not tracked the effects of the drugs (pro and con) over many years. Most followed people for just a year or less.

Even so, the studies help clarify the benefits and adverse effects of most diabetes drugs, and signal typical and expected effects among a group of people with diabetes. But very importantly, such studies do not reveal how a specific person with diabetes will respond to any particular drug. Only your doctor and you can decide precisely which drug or drug combination is best for you given your health status, weight, other medical needs, and the severity of your diabetes. And only you and your doctor can track how well a particular drug or combination of drugs is helping you, or not helping you.

Tables 2, 3, and 4 summarize the comparative evidence on the diabetes drugs. The tables reflect the results from 166 studies. Table 2 presents summary evidence of the various classes of diabetes drugs. Table 3 is more specific, with detailed information on the individual drugs. As such, Table 3 takes a bit more time to figure out. But it contains information unique to this report and which may be valuable for your treatment decision.

Table 4 presents a run-down of the pros and cons of each drug class. The tables contain some material that is duplicative. On balance, though, they give you three ways to assess the important differences among diabetes drugs.

As mentioned earlier, the diabetes drugs have distinctly different “safety profiles.” This factor may be the primary driver of your and your doctor’s decision — for initial and on-going treatment.

For example, the evidence clearly shows that the sulfonylureas pose a higher risk of hypoglycemia than metformin or the thiazolidinediones (Avandia and Actos). Specifically, between 9 and 22 percent of people taking one of the sulfonylurea drugs can expect to have an episode of potentially dangerous low blood sugar, compared to zero to 7 percent taking metformin.

The risk of hypoglycemia is about the same for the sulfonylureas and repaglinide (Prandin), but two recent studies suggest that repaglinide may cause less hypoglycemia in seniors or in people who skip meals.

As good as it looks in other ways, metformin has been associated with rare occurrences of lactic acidosis — a build up of lactic acid in the blood that can be fatal. This rare risk appears to exist mostly for people with diabetes who also have kidney disease and/or heart failure. As a result, such patients should not be prescribed metformin.

Minor but annoying side effects may also play a role in your choice of a diabetes medicine. For example, gastrointestinal side effects — including bloating, gas, nausea, and diarrhea — are more frequent with metformin and also acarbose.

One of the newer classes of drugs poses an elevated risk of heart failure. Evidence overwhelmingly indicates that the thiazolidinediones — Avandia (more about this drug below) and Actos — pose a 1.5 to 2 times increased risk of congestive heart failure compared to other diabetes medicines. Between 1 and 3 people in 100 without a history of heart disease will develop the condition if they take one of these drugs. In contrast, metformin and the sulfonylureas do not raise the risk of heart failure in any significant way compared to the general risk of this condition among people with diabetes, which is higher than normal.

Because of the clear evidence of heart failure risk, both Actos and Avandia carry a high-profile “black box” warning about it on their labels (guidance to doctors and patients on how to use them). If you are taking one of these medicines and have swelling of any part of your body, sudden weight gain, or breathing problems, you should contact your doctor immediately.

Don’t Take Avandia; Actos a Last Resort

In addition to heart failure, Avandia also increases the risk of heart attack and stroke. For that reason, the FDA has restricted use of the medication (and combination products that contain it) only for people who have persistent high blood sugar levels even after taking another medication and who can’t take an alternative such as Actos. Avandia and combination products, Avandamet and Avandaryl, are no longer available at pharmacies. Instead, if you need one of those medications, both you and your doctor have to register with a special program to have them delivered by mail-order.

If you are already taking Avandia, Avandamet, or Avandaryl, and they are working to control your blood sugar, you can continue to take them, but we strongly recommend you discuss with your doctor whether they are appropriate for you.

Both Actos and Avandia have also been linked to a slightly increased risk of fractures of the upper and lower limbs, such as the wrist or ankle, in women. The risk was small — about 2 percent higher in people taking Avandia or Actos compared with those taking other diabetes drugs, according to preliminary studies.

Actos increases the risk of bladder cancer in people who take it for a year or longer. The risk applies to all drugs containing pioglitazone, including Actoplus Met, Actoplus Met XR, and Duetact. France banned Actos and combination pills due to the cancer risk.

Our medical advisors say that people with diabetes should use Actos only as a last resort, which means only if all other options have failed. People who have previously had or currently have bladder cancer should not use Actos or the combination pills that contain it at all.

If you’re on Actos, ask your doctor if it’s really necessary and if you should switch to another drug, such as metformin either alone or in combination with glipizide or glimepiride. Also, be alert for signs of bladder cancer, which include blood or red color in your urine, urgent need to urinate or pain while urinating, and pain in your back or lower abdomen. Contact your doctor if you experience any of those symptoms.

Actos has been heavily promoted to doctors and consumers in the U.S. As a result, it may be over-prescribed to people who would do just as well to take metformin and/or a sulfonylurea. Both Actos and Avandia (until recently) have been marketed specifically to minorities as well, but there is no good evidence that any diabetes medicine is more effective or safer in African-Americans, Hispanics, or American Indian patients than in other ethnic groups.

Januvia and Onglyza — the newest oral diabetes drugs

Januvia and Onglyza are the first two drugs in a new class of diabetes medications called dipeptidyl peptidase 4 inhibitors. No studies on these drugs have followed patients for more than two years, so their effectiveness and safety profiles are not clearly established yet. Neither Januvia nor Onglyza has been shown to lower HbA1c as well as metformin or glipizide, so we do not recommend them as first-line drugs. Another drawback is that both are significantly more expensive than generic versions of other diabetes drugs.

Finally, as a reminder, if your diabetes is not controlled by pills, you may have to take insulin or one of the newer drugs available by injection only.

Table 4. Advantages and Disadvantages of the Oral Diabetes Drugs



The sulfonylureas (glyburide, glimepiride, glipizide)  
  • Fast onset of action
  • No affect on blood pressure
  • No affect on LDL cholesterol
  • Convenient dosing
  • Low cost
  • Lower risk of GI side effects than metformin
  • Weight gain (5 to 10 pounds on average)
  • Heightened risk of hypoglycemia
  • Glyburide has slightly higher risk of hypoglycemia compared with glimepiride and glipizide
  • Low risk of hypoglycemia
  • Not linked to weight gain
  • Good effect on LDL cholesterol
  • Good effect on triglycerides
  • No effect on blood pressure
  • Low cost
  • Higher risk of GI side effects (nausea and diarrhea)
  • Cannot be taken by people with diabetes who have moderate or severe kidney  disease or heart failure because of risk of lactic acid build-up
  • Less convenient dosing
The alpha-glucosidase inhibitors (acarbose, miglitol)  
  • Slightly lower risk of hypoglycemia compared to sulfonylureas
  • Not associated with weight gain
  • Decreases triglycerides
  • No effect on cholesterol
  • Less effective than most other diabetes pills in lowering HbA1c
  • Higher risk of GI side effects than other diabetes pills except metformin
  • Inconvenient dosing
  • High cost
The thiazolidinediones (Actos, Avandia)  
  • Low risk of hypoglycemia
  • Slight increase in “good”  (HDL) cholesterol
  • Actos linked to decreased triglycerides
  • Convenient dosing
  • Higher risk of heart failure
  • Weight gain (5 to 10 pounds)
  • Linked to higher risk of edema (fluid build-up)
  • Linked to higher risk of anemia
  • Increase in “bad” (LDL) cholesterol
  • Avandia linked to increased triglycerides and higher risk of heart attack
  • Actos linked to increased risk of bladder cancer
  • Slower onset of action
  • Rare risk of liver problems; requires monitoring
  • Linked to increased risk of upper and lower limb fractures
  • High cost
The meglitinides (nateglinide, repaglinide)  
  • No bad effect on cholesterol
  • Rapid onset of action
  • Repaglinide associated with risk of hypoglycemia and weight gain similar to sulfonylureas
  • Nateglinide has less effect on HbA1c
  • Inconvenient dosing
  • High cost
The DPP-inhibitors (Januvia, Onglyza)  
  • When added to metformin, lower risk of hypoglycemia compared with a sulfonylurea
  • Few known side effects (but they are new drugs)
  • Lower risk of GI side effects than metformin
  • Convenient dosing
  • Both drugs associated with pancreatitis or inflammation of the pancreas
  • Reduce HbA1c less than several other diabetes drugs
  • May only be valuable as second drugs added to another medication
  • Less data on potential side effects compared to older drugs
  • High cost

1. Bennett WL, et al, Oral Diabetes Medications for Adults With Type 2 Diabetes: An Update. Comparative Effectiveness Review No. 27. March 2011 (Prepared by Johns Hopkins University Evidence-based Practice Center under Contract No. 290-02-0018.) AHRQ Publication No. 11-EHC038-EF. Rockville, MD: Agency for Healthcare Research and Quality. March 2011. Available at:

2. Bennett WL., et al, Comparative effectiveness and safety of medications for type 2 diabetes: an update including new drugs and 2-drug combinations. Ann Int Med. (May 3 2011); Web published in advance of print publication, March 14, 2011.

Our 'Best Buy' recommendations

Taking effectiveness, safety, side effects, dosing, and cost into consideration, we have chosen the following as Consumer Reports Best Buy Drugs if your doctor has decided that you need medicine to control your diabetes:

  • Metformin and Metformin Sustained-Release — alone or with glipizide or glimepiride
  • Glipizide and Glipizide Sustained-Release — alone or with metformin
  • Glimepiride — alone or with metformin

All these medicines are available as low-cost generics, either alone or in combination. (See Table 5.) In recent years, a strong medical consensus has emerged in the U.S., Europe, and Australia that most newly diagnosed people with diabetes who need a medicine should first be prescribed metformin.

Based on the systematic evaluation of diabetes drugs that forms the basis of this report, we concur with that advice. Unless your health status prevents it, try metformin first. If metformin fails to bring your blood glucose into normal range, you may need a second drug. Most commonly that should be one of the two other Best Buys we have chosen.

If you are unable to take metformin or do not tolerate it well, you face a choice of one of the sulfonylureas or a newer medicine as your first line medicine. Despite the elevated risk of hypoglycemia, we recommend trying glipizide or glimepiride. If glipizide or glimepiride alone fail to bring your blood glucose into control and keep your HbA1c at or below 7 percent, your doctor will likely recommend a second drug.

If upon initial diagnosis your glucose and HbA1c are quite high, you may be prescribed a combination of two drugs at the beginning of treatment — usually metformin plus a sulfonylurea.

How we picked the 'Best Buys'

Our evaluation is based in large part on an independent review of the scientific evidence on the effectiveness, safety, and adverse effects of the oral diabetes medicines conducted by the Johns Hopkins University-evidence based Practice Center under contract number 290-02-0018 with the Agency for Healthcare Research and Quality. This analysis reviewed hundreds of studies, including those conducted by the drugs’ manufacturers. A synopsis of the results of this analysis, written by the researchers at Johns Hopkins, forms the basis of portions of this report.

However, no statement in this report should be construed as the official position of the Johns Hopkins Evidence-based Practice Center, the Agency for Healthcare Research and Quality, or the U.S. Department of Health and Human Services. In particular, none of those entities played any role in our selection of the Best Buy diabetes drugs. Consumer Reports, publishers of Consumer Reports Best Buy Drugs, is solely responsible for those, and for all other specific advice and recommendations in this report.

Additional sources used in writing this report include:

-An analysis of selected classes of diabetes drugs conducted by the Drug Effectiveness Review Project (DERP), an initiative to evaluate the comparative effectiveness and safety of hundreds of prescription drugs

-Three reviews of oral diabetes drugs by the Cochrane Collaboration

-An American Medical Association monograph on the oral diabetes drugs

-A Veteran’s Administration monograph on diabetes drugs

-Recent guidelines issued by the American Diabetes Association and American College of Cardiology

-Selected recent articles in peer-reviewed journals (See References)

The prescription drug costs we cite were obtained from a healthcare information company that tracks the sales of prescription drugs in the U.S. Prices for a drug can vary quite widely, even within a single city or town. All the prices in this report are national averages based on sales of prescription drugs in retail outlets. They reflect the cash price paid for a month's supply of each drug in August 2012.

Consumer Reports selected the Best Buy Drugs using the following criteria. The drug had to:

-Be as effective or more effective than other oral diabetes medicines

-Have a safety record equal to or better than other oral diabetes medicines

-Cost roughly the same or less than other oral diabetes medicines


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Editor's Note:

These materials are made possible by a grant from the state Attorney General Consumer and Prescriber Education Grant Program, which is funded by the multi-state settlement of consumer-fraud claims regarding the marketing of the prescription drug Neurontin (gabapentin).

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