Drug Combination Safe and Effective for Diabetes Treatment

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Efficacy and safety of topiramate in combination with metformin in the treatment of obese subjects with type 2 diabetes: a randomized, double-blind, placebo-controlled study, by H. Toplak and colleagues. Int J Obes 31: 138-146, 2007

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

Although lifestyle changes, such as adopting a more healthful diet and increasing physical activity, can help reduce obesity and the chance of developing diabetes, it is difficult for many people to stick to healthful habits. Doctors are interested in other ways to help people avoid the problems of obesity and diabetes, such as drug therapy.

Some studies have suggested that topiramate, a drug usually given to control migraine headaches and seizure disorders, can help people lose weight. But it isn’t known whether topiramate is safe for people to take, particularly if they are already taking an anti-diabetes drug such as metformin, and whether topiramate is effective in helping people lose weight.

Why did the researchers do this particular study?

The researchers wanted to see whether topiramate is safe and effective in treating obese people with diabetes who are taking metformin.

Who was studied?

The study included 646 participants followed at 68 medical centers in Canada, Europe, and South Africa. All of the participants were overweight or obese, were between 18 and 75 years old, and had been on metformin therapy for at least 4 months.

How was the study done?

Participants had a physical exam and blood drawn for lab tests. One group of participants was prescribed 96 mg of topiramate per day, while another took 192 mg of topiramate daily, and another group received a sugar pill.

All participants engaged in a program of exercise and behavior modification and followed a diet designed to reduce intake by 600 calories per day.

What did the researchers find?

After 24 weeks of therapy, participants taking topiramate lost significantly more weight, had lower A1C (a long-term measure of blood glucose control) levels, and lower systolic blood pressure than those receiving placebo. People on the higher dose of topiramate showed greater improvements than people on the lower dose.

What were the limitations of the study?

The study period was fairly short. Different results may be seen in a longer follow-up period.

What are the implications of the study?

Topiramate is safe and effective for the treatment of obese patients with type 2 diabetes, but more study needs to be done, the researchers conclude.