NEW YORK (Reuters Health) - Overeating is likely the greatest contributor to the weight gain that can occur when a diabetic begins using insulin, new research suggests.

However, overeating can be difficult for doctors to recognise since diabetics may underreport their food intake, according to the findings in the journal Diabetes Care.

Dr. Miriam Ryan, from CHU Angers, France and colleagues assessed the impact of food intake on weight gain in 23 type 1 and 23 type 2 diabetic adults starting insulin therapy.

During the study, the type 1 diabetics gained weight gained an average of 10.3 pounds and type 2 diabetics gained an average of 4.0.

The weight gain could not be explained by a slowing of the body's metabolism, decrease in physical activity, or increase in sugar in the urine, leaving the authors to conclude that it was primarily due to overeating.