According to researchers, adults who treated their disease with multiple daily insulin injections or continuous infusion were more likely to become overweight after 6 years. This group gained an average of 4.75 kilograms (9.5 pounds) more than patients who took one or two insulin shots a day. The weight gain translated into an increase in body mass index (BMI) of 1.5 for men and 1.8 for women.
BMI, which takes into account a person's weight in relation to their height, is considered a more accurate measure of overweight and obesity than body weight alone. A person with a BMI of at least 25 is considered overweight and one with a BMI of 30 and above is considered obese.
The findings should not prevent some patients from treating their disease intensively since this approach is associated with significant improvements in several diabetes-related complications, the study's authors explain in the October issue of Diabetes Care.
Instead, the investigators call for more research into why intensive insulin therapy is associated with weight gain, and ways to prevent this weight gain.
Previous research has shown that intensive insulin therapy can lower the risk of some of the medical complications associated with type 1 diabetes. However, it may also lead to severe hypoglycemia--a significant drop in blood sugar--and weight gain.
To investigate, David M. Nathan of Massachusetts General Hospital in Boston and colleagues from the Diabetes Control and Complications Trial Research Group compared weight gain and body composition in a group of more than 1,200 patients aged 18 to 39, who followed a conventional or intensive insulin regimen.
The results show that weight gain was most rapid in the first year. Although the rate of weight gain slowed in subsequent years, patients did not shed any pounds, even after 9 years. Women tended to put on weight at a faster rate than men did, and women treated intensively tended to gain weight in their abdomens.
Abdominal obesity, the authors note, is believed to be a risk factor for heart disease.
Some patients, however, put on muscle in addition to fat. Among those who did not gain major amounts of weight--or increase their BMI by more than 5--intensive therapy was associated with an increase in muscle mass but not fat. Patients who gained the most weight had higher proportions of both muscle and fat.
"Intensive therapy for type 1 diabetes produces substantial excess weight gain compared with conventional therapy. However, the additional weight appears to include lean tissue as well as fat," the researchers conclude.
SOURCE: Diabetes Care 2001;24:1711-1721.