Metformin (trade name Glucophage) was approved for use in the United States in April, 1995. It has been used for 20 years in Europe, and has a good safety record. It works in an entirely different way from insulin and the traditional oral hypoglycemic agents (Micronase, Diabeta, Glucotrol and others). It decreases sugar production by the liver, and increases sugar uptake. When used alone, it does not cause hypoglycemia ("insulin reactions" or "low blood sugar"); however, if one takes an oral hypoglycemic (like Micronase) plus Glucophage, hypoglycemia can occur.
The main side effects of Glucophage are gastrointestinal: nausea, vomiting, diarrhea, heartburn, loss of appetite, and a metallic taste in the mouth. If it is taken with food, these side effects are less of a problem. These side effects usually resolve with continued use (after a few weeks). The most dangerous (and fortunately uncommon) side effect is lactic acidosis. This is when too much lactic acid (a breakdown product of sugar) accumulates in the bloodstream; when this happens, fatigue, rapid breathing, shortness of breath, vomiting, upper abdominal pain, increased thirst and profound weakness will develop. If unrecognized and untreated, it can lead to death. This is most likely to happen in people with kidney disease, severe liver disease, congestive heart failure, or emphysema; it can also happen during very stressful situations, such as severe fcinfections with fever, X-ray studies in which a dye is given by vein, or surgery. Lactic acidosis occurs very rarely in people taking Glucophage who are otherwise healthy. However, if you are planning to have surgery or an X-ray dye study, stop the Glucophage 2 days before and don't resume it until you have fully recovered from the procedure.
Glucophage is usually started in a dose of 500 mg twice each day (with breakfast and supper). The dose is gradually increased to a maximum dose of 850 mg three times each day. For most diabetics poorly controlled with oral medicines alone, the addition of Glucophage will result in a drop in their fasting sugar of about 40-70 mg/dl.
During the first few months that you take this medicine, I will want you to check your sugars regularly, and see me about once each month. If you think that you may be developing lactic acidosis, call my office so that we can arrange to see you immediately.
In summary, Glucophage is a promising new (old) medicine that will help overweight type II diabetics improve the control of their blood sugars. It has some minor gastrointestinal side effects, and rarely can cause lactic acidosis. If you have any questions regarding this medication, please discuss them with me.