A comparative review assesses the effectiveness of various agents in adults with type 2 diabetes mellitus.

Insulin resistance accompanied by a progressive deficiency in insulin secretion distinguishes type 2 diabetes mellitus. The number of Americans diagnosed with the disorder more than doubled between 1980 and 2004, from 5.8 million to 14.7 million, according to the American Association of Clinical Endocrinologists. Clinical trials and observational studies have demonstrated that when the serum glucose level is better controlled, microvascular complications (those involving the eyes, kidneys, or nerves, for example) are decreased. There may also be some reduction in macrovascular complications (heart attack, for example), although that effect is more controversial. The effects of specific oral diabetes medications on those events are less clear.

By analyzing 216 published studies of adults with type 2 diabetes, the authors of a comprehensive review compared the effectiveness, safety, risks, adverse events, and costs associated with the use of the diabetes drugs acarbose, glimepiride, sulfonylureas, glyburide, metformin, miglitol, nateglinide, pioglitazone, repaglinide, and rosiglitazone.

They found that all of the drugs are comparably effective in reducing the serum glucose level. Some older agents were even superior to newer, more expensive drugs. Furthermore, metformin is less likely to cause weight gain and has been shown to decrease the level of low-density lipoprotein ("bad") cholesterol.

The crux of the matter. In the treatment of type 2 diabetes, currently available oral hypoglycemic agents are comparably effective in lowering the serum glucose level.