For people with Type 2 diabetes, diet and exercise often aren't enough to keep blood sugar levels in a healthy range. That's where medication comes in.
Metformin typically is the first choice for a diabetic patient beginning drug treatment. It's been around for decades (and marketed in the U.S. for 15 years) and is considered a very safe drug. Other advantages include the fact that it doesn't cause weight gain — as do some other diabetes medications. Plus it's generic and thus cheaper, says Dr. Andrew Drexler, director of the Gonda Diabetes Center at UCLA.
If blood sugar is not sufficiently controlled by the first-line treatment after, say, three to six months of treatment, doctors usually recommend adding a second medication to the mix.
A host of long-term studies have found that a majority of patients end up taking at least two drugs within a decade of beginning treatment. That second drug may be any one of the others on the market, says Dr. David Kendall, the chief medical officer for the American Diabetes Assn. Numerous studies comparing drug combinations have found no clear winner: "Almost regardless of what you pick, you're going to do better," he says.
The number and variety of diabetes medications can be bewildering, but, on the plus side, that means choice. Some people may prefer easy-to-take drugs; others want one that won't cause weight gain; still others may desire something that allows them to adjust dosing on a daily basis. "It's the perfect example of personalized medicine," Kendall says.
In addition to the immediate effects of diabetes meds (glucose control and side effects such as nausea and diarrhea), patients and doctors must consider the long-term effects of drugs taken every day for years. A possible plus for metformin: A recent review of 11 studies reported that people taking it have a 31% lower risk of developing or dying of cancer compared with other diabetes treatments.
Medications for diabetes generally fall into just three categories based on what they do. They either affect food absorption, increase availability of insulin or increase the body's responsiveness to insulin. Here's the breakdown.
Metformin (Fortamet, Glucophage), an insulin-sensitizing drug, is taken by mouth twice a day. Users should test their blood sugar two to five times per week. This is the first-line drug.
Pluses and minuses: Metformin has minimal effects on body weight, rarely causes low blood sugar problems and is available in generic form. Long-term studies suggest the drug may reduce the risk of some cancers. It can't be used in people with kidney or liver disease, and some people experience gastrointestinal side effects, such as nausea or diarrhea.
The sulfonylureas, such as glipizide (Glucotrol), glimepiride (Amaryl) and glyburide (DiaBeta, Glynase), increase insulin production, are once- or twice-daily pills and don't require daily sugar testing.
Pluses and minuses: Sulfonylureas are quick-working, effective sugar-lowering medications, and they're available in cheaper generic forms. They can cause low blood sugar and moderate (2 to 3 pounds) weight gain.
The glitinides, such as repaglinide (Prandin) and nateglinide (Starlix), increase insulin production. They are taken by mouth before meals up to four times a day.
Pluses and minuses: They work quickly, but they can cause weight gain and low blood sugar.
The glitazones, such as rosiglitazone ( Avandia) and pioglitazone ( Actos), are insulin-sensitizing drugs taken by mouth once a day. Users should test their blood sugar three to five times weekly.
Pluses and minuses: Low blood-sugar events are rare. Weight gain and fluid retention are common side effects. Over the long term, Avandia appears to increase the cardiovascular risks already faced by patients with diabetes, and the Food and Drug Administration now requires that patients sign consent forms stating they understand the risks and that doctors certify that other therapies have failed before prescribing it. Studies have been mixed on whether Actos has the same risks. The FDA is reviewing whether Actos raises the risk of bladder cancer.
The GLP-1 agonists, such as exenatide (Byetta) and liraglutide (Victoza), augment the body's ability to make insulin. They have to be injected once or twice a day, and blood sugar must be closely monitored, up to twice a day.
Pluses and minuses: They promote weight loss and confer little risk of low blood-sugar episodes. They can cause nausea and diarrhea and, in rare cases, kidney failure.
The DPP-4 inhibitors, such as saxagliptin (Onglyza) and sitagliptin (Januvia), also augment the body's ability to make insulin. They are taken by mouth once a day.
Pluses and minuses: They don't cause weight gain and are unlikely to cause low blood sugar but can promote respiratory tract infections.
The alpha-gludosidase inhibitors, such as acarbose (Precose) and miglitol (Glyset), slow the breakdown of food carbohydrates into glucose. They are taken by mouth three times per day with meals, and blood glucose should be checked after meals.
Pluses and minuses: They are effective when used in combination with other medicines, but abdominal pain, gas and diarrhea are common side effects.