In the DCCT, intensively treated patients gained an average of 4.75 kg more than conventionally treated patients (p < 0.0001 ). This finding represented an excessive increase in BMI of 1.5 kg/m2 in men and 1.8 kg/m2 in women. Weight gain was most rapid in the first year of therapy. By year 9 of the study, BMIs had increased >5 kg/m2 in 35% of women and 28% of men, whereas comparable figures in the conventionally treated women and men were approximately 13% and 4%.
Waist-to-hip ratio did not differ between treatment groups. However, intensively treated DCCT subjects who were in the highest quartile of weight gain had increased waist-hip ratios and BMIs, associated with a slightly higher blood pressure and a relatively atherogenic lipid profile. These patients may be predisposed to the insulin resistance syndrome, and their tendency for abdominal obesity may have been exposed by intensive insulin therapy. Long-term follow-up of these patients in EDIC will be of great interest.
Among patients without major weight gain, those on intensive therapy had a greater fat-free mass with no difference in adiposity. Although the benefits of intensive management on microvascular complications in type 1 diabetes are clear, improved understanding of the causes of weight gain and methods to control it are needed.