When first diagnosed with Type 2 diabetes, most patients are advised to regulate blood sugar with exercise, diet and stress management. If that fails, the first medication that they receive is usually metformin, said Sanjay Kaul, a cardiologist at the Cedars-Sinai Heart Institute and member of the Food and Drug Administration's Avandia panel.
The medication has the five characteristics physicians look for in diabetes medications, Kaul said: few potential complications, safety, tolerability, ease of use and a low cost.
"Metformin is preferred by professional societies as the treatment of first choice for diabetic patients," he said. "It is relatively safe, without side effects, well tolerated, weight neutral and inexpensive. And evidence shows it may save lives."
It decreases the amount of sugar (glucose) the body takes from foods and the amount of glucose produced by the liver. About 15% to 20% of diabetes patients cannot tolerate the drug because of gastric side effects or kidney problems, said Richard Bergenstal, president of medicine and science for the American Diabetes Assn. and executive director of the International Diabetes Center.
When first starting diabetes medications, some patients experience side effects like such as water retention. These are usually seen within a week or so, and three months is sufficient time to see if a drug is affecting glucose reduction, Bergenstal said.
If a patient can't tolerate the drug or it doesn't decrease blood sugar adequately, a second medication is typically added to the regimen. About a dozen categories of drugs are available in the second class of medications, Bergenstal said, but four of them make up about 90% of prescriptions.
One group is sulfonylureas (such as Amaryl, or glimepiride), which help the pancreas release more insulin. A second is DPP-4 inhibitors (such as Onglyza, or saxagliptin). DPP-4 is an enzyme that blocks the secretion of the hormone GLP-1, which stimulates the release of insulin. The third is GLP-1 agonists (such as Byetta, or exenatide), which mimic the actions of GLP-1. And lastly, thiazolidinediones (such as Avandia, or rosiglitazone, and Actos, or pioglitazone), which increase the body's sensitivity to insulin.
If patients still don't meet their target glucose levels, a third medication is added to the regimen. This could be another of the drugs not used in the second tier, background insulin (long-acting, which stays in the bloodstream for 24 hours) or a thiazolidinedione. If patients continue to have problems, the fourth, and final, level of treatment is insulin therapy.