Comparing Two Medications for Type 2 Diabetes

Schernthaner G, Matthews DR , Charbonnel B, et al.: Efficacy and safety of pioglitazone versus metformin in patients with type 2 diabetes mellitus: A double-blind, randomized trial. J Clin Endocrinol Metab 89:6068-6076, 2004.

What is the problem and what is known about it so far?

Metformin is a medication used to lower blood glucose levels for patients with diabetes. Another drug, pioglitazone, also is used to lower blood glucose levels. More studies were needed to find out if one drug worked as well as the other and if there were other benefits to either drug.

Previously, the researchers compared pioglitazone with metformin in patients with type 2 diabetes who had never taken diabetes medications. They also wanted to know if these medications affected blood fat levels, in how the body uses insulin, and how the body gets rid of insulin during glucose tolerance tests.

Who was studied?

A total of 1,199 men and women from 12 European countries were studied. They were between 35 and 75 years old. All study members had type 2 diabetes that was not controlled well with diet alone.

How was the study done?

The patients were divided into two groups. One group received metformin and the other received pioglitazone. All patients were advised on healthy eating at the beginning of the study. If a patient's weight or HbA1c (a test that shows blood glucose levels over time) increased, he or she received more dietary help. The study lasted 12 months.

What did the researchers find?

Both patient groups had a similar decrease in HbA1c levels. The pioglitazone group had a slightly lower fasting blood glucose level and fasting insulin level. Fasting measurements are taken before people have eat.

Only a few patients also took medication to reduce fats in their blood. HDL, the "good" cholesterol, increased a lot in those taking pioglitazone. The number of side effects (such as being tired and nauseous) was small and about the same in both groups.

What are the implications of the study?

Pioglitazone and metformin show similar results on HbA1c during a year of treatment. The researchers found that both medications work well for type 2 diabetes patients who have never taken diabetes medications. Because the medications work differently, it is possible they could be taken together to lower blood glucose levels.