Insulin Does not Cause More Weight Gain in Heavier People

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Weight gain and insulin requirement in type 2 diabetic patients during the first year after initiating insulin therapy dependent on baseline BMI, by G. Biesenbach and colleagues. Diabet Obes Metab 8:669–673, 2006.

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

People with diabetes who take insulin often gain weight. This is a problem for many people, particularly if they are overweight to begin with. Since heavier people tend to need more insulin, there is a concern about whether they will gain even more weight.

Why did the researchers do this particular study?

The researchers wanted to see whether there are differences in how much insulin people need and how much weight they gain.

Who was studied?

The study included 192 people who were newly diagnosed with type 2 diabetes.

How was the study done?

All participants had a physical exam and blood drawn for lab tests. Participants were categorized into ranges of body mass index (BMI, a way of measuring weight compared to height) at the beginning of therapy. The categories included those with a BMI of less than 26 (which is considered “normal weight”), a BMI of 26 to 30 (which is considered “overweight”), and a BMI of more than 30 (which is considered “obese”).

Participants had another physical exam after a 12-month follow-up period.

What did the researchers find?

After starting insulin, people in all three groups gained weight, but there were no differences among the groups in the amount of weight gained, the amount of insulin needed, or the levels of A1C (a measure of long-term glucose control).

Adding metformin to treatment reduced the amount of insulin people needed, regardless of how overweight they were.

What were the limitations of the study?

A relatively small number of participants were very overweight or obese, and more than half were near the normal BMI range (less than 26). A study with heavier participants may yield different results.

What are the implications of the study?

Heavier people do not gain more weight when they start insulin therapy. Concerns that they will gain more weight because they need to take more insulin appear to be unfounded.

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