OBJECTIVE—In participants of the Diabetes Prevention Program (DPP) randomized to intensive lifestyle modification (ILS), meeting ILS goals strongly correlated with prevention of diabetes in the group as a whole. Men met significantly more ILS goals than women but had a similar incidence of diabetes. Therefore, we explored sex differences in risk factors for diabetes and the effect of ILS on risk factors.

RESEARCH DESIGN AND METHODS—Baseline risk factors for diabetes and percent change in risk factors over the first year in men versus women were compared using Wilcoxon's rank-sum tests.

RESULTS—At baseline, men were older and had a larger waist circumference; higher fasting plasma glucose concentration, caloric intake, and blood pressure; and lower HDL cholesterol and corrected insulin response than women, who were less physically active and had a higher BMI (P < 0.01 for all comparisons). Over the first year of the DPP, no sex difference in risk factors for diabetes was observed for those who lost <3% body weight. Weight loss of 3–7% body weight yielded greater decreases in 2-h glucose (P < 0.01), insulin concentration (P < 0.04), and insulin resistance (P < 0.03) in men than in women. Weight loss of >7% body weight resulted in greater decreases in 2-h glucose (P < 0.01), triglyceride level (P < 0.01), and A1C (P < 0.03) in men than in women.

CONCLUSIONS—Weight loss >3% body weight yielded greater reduction in risk factors for diabetes in men than in women. Despite the more favorable effects of ILS in men, baseline risk factors were more numerous in men and likely obscured any sex difference in incident diabetes.