Is it true that there is a new medication for the treatment of diabetes?
Q: At the end of December 1994, the Food and Drug Administration approved the drug metformin (Glucophage) for the treatment of diabetes. This drug, useful primarily for patients with type II, or noninsulin dependent diabetes mellitus (NIDDM), will be available in pharmacies within the next few weeks.
Although approved only recently in this country, metformin is not a new drug. In fact, it has proven to be effective and safe during its use in large numbers of patients in many other countries, including Canada, Britain and in Western Europe, for almost 40 years.
Metformin and sulfonylureas, the other type of oral medications for patients with NIDDM, produce similar responses in blood sugar (glucose) levels, although they work in entirely different ways. The sulfonylureas increase blood insulin levels by stimulating the release of insulin from the pancreas.
By contrast, metformin does not increase pancreatic secretion or blood levels of insulin. Instead, it enhances the activity of insulin by reducing the production and release of glucose into the blood by the liver and by increasing the removal of glucose from the blood, primarily by muscles.
Metformin is a pill taken two or three times daily. It can be prescribed as the first drug treatment for NIDDM; for patients who do not respond to sulfonylureas; or in combination with sulfonylureas when these don't achieve adequate control of blood glucose levels.
Because metformin and sulfonylureas work in different ways, the combination of the two is generally more effective than either one alone. Also, because metformin does not raise blood insulin levels, it rarely causes hypoglycemia (low blood glucose levels), a potential side effect of treatment with either sulfonylureas or insulin.
Whereas people taking sulfonylureas tend to gain some weight, those using metformin usually lose small amounts of weight. In addition, metformin has beneficial effects on blood lipid levels. Metformin is particularly effective in lowering triglycerides, the lipid most commonly elevated in those with diabetes; but metformin also lowers total and LDL cholesterol while raising the good" HDL cholesterol level.
The most common side effects from metformin are nausea, loss of appetite and diarrhea. Approval of metformin for use in the United States. was slowed by the fact that another drug (phenformin) in the same class with metformin had been banned some years ago because it caused rare cases of a dangerous complication known as lactic acidosis. While the widespread use of metformin throughout the world has shown that lactic acidosis is extremely unlikely, the drug should not be taken by diabetic patients with other conditions, such as liver disease, poor kidney function or congestive heart failure, that can raise the blood level of lactic acid.
Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.