September 22, 2016

Metformin Is Recommended for Prediabetes

In a controlled trial, 600 overweight and obese people with prediabetes were given metformin in Chennai,India.

Metformin is in the biguanide class. It works by decreasing glucose production by the liver and increasing the insulin sensitivity of body tissues. It also can possibly help patients to lose weight, and possibly prevent some forms of cancer. Metformin was discovered in 1922. It is on the World Health Organization’s List of Essential Medicines, the most important medications needed in a basic healthcare system. Metformin is believed to be the most widely used medication for diabetes, which is taken by mouth. It is available as a generic medication.

For those patients who are under age 60 with prediabetes, the ADA has recommended metformin for those with a BMI over 34 and for women with gestational diabetes in the past. But, for others, especially for those over the age of 60, and even teenagers who rarely are treated with metformin, the study found that just 3.7% of those with prediabetes were actually prescribed metformin, over a 3-year period. Since metformin has been around since 1950 and even longer overseas and has even been shown to possibly prevent certain kinds of cancer, why should it not be standard procedure to provide all those with prediabetes the option to be treated with metformin?

With the cost for the 29 million patients with diabetes at over 300 billion dollars, should we be asking the question: with more than 90 million people in the U.S. with prediabetes — a number that’s still growing — why doesn’t the FDA or the ADA recommend starting patients on metformin immediately after diagnosis?

In a randomized controlled trial of almost 600 overweight or obese people with prediabetes in Chennai, India, significantly fewer of those who followed an intensive lifestyle-intervention program, with metformin if needed, went on to develop diabetes compared with persons managed with standard care. But, the intervention’s effectiveness varied according to differences in the metabolic nature of their prediabetes.

The intervention in the trial, called the Diabetes Community Lifestyle Improvement Program (D-CLIP), was modeled after the U.S. Diabetes Prevention Program (DPP), but adapted for India. It consisted of 4 months of weekly educational sessions on diet and exercise, followed by a 2-month maintenance program of weekly educational meetings, plus metformin as needed.

Patients in the intervention arm who had both impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) showed a 36% lower risk of developing diabetes compared with those in the control arm. And those with only isolated IGT had a 31% lower risk. But the benefit was smaller in patients with only isolated IFG at baseline; they showed a 12% lower risk of developing diabetes.

Participants in the control arm received standard care, which consisted of a one-time visit with a physician, a dietitian, and a fitness trainer, and a group class on diabetes prevention (with instruction on, for example, how to follow a low-fat diet rich in complex carbohydrates and fresh fruits and vegetables, and how to increase physical activity), but none received metformin. Low-fat diet has to have been a factor in the study and caused some data irregularities.

Participants in the intervention group received 16 weekly core classes for 4 months followed by eight weekly maintenance classes for 2 months. The classes were 1.5 hours long, for groups of eight to 24 participants, and included an exercise class following the educational talk.

The intervention’s goals were the same as those in the DPP: greater than 7% weight loss and greater than 150 minutes/week of moderate-intensity exercise. At 4 months, participants who still had IFG and either IGT or HbA1c greater than 5.7% received 500 mg twice-daily metformin. During the 3-year follow-up, a per-year mean of 11.1% of participants in the control group vs 7.8% of participants in the intervention group developed diabetes (P = .014). The number needed to treat to prevent one case of diabetes with the intervention was 9.8.

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