Impact of BMI and the Metabolic Syndrome on the Risk of Diabetes in Middle-Aged Men

OBJECTIVE: The existence of an obese subgroup with a healthy metabolic profile and low diabetes risk has been proposed; yet long-term data are lacking. We aimed to investigate associations between combinations of BMI categories and metabolic syndrome and risk of type 2 diabetes in middle-aged men. RESEARCH DESIGN AND METHODS: At age 50, cardiovascular risk factors were assessed in 1,675 participants without diabetes in the community-based Uppsala Longitudinal Study of Adult Men (ULSAM) study. According to BMI/metabolic syndrome status, they were categorized as normal weight (BMI <25 kg/m²) without metabolic syndrome (National Cholesterol Education Program criteria, n = 853), normal weight with metabolic syndrome (n = 60), overweight (BMI 25-30 kg/m²) without metabolic syndrome (n = 557), overweight with metabolic syndrome (n = 117), obese (BMI >30 kg/m²) without metabolic syndrome (n = 28), and obese with metabolic syndrome (n = 60). We investigated the associations between BMI/metabolic syndrome categories at baseline and diabetes incidence. RESULTS: After 20 years, 160 participants had developed diabetes. In logistic regression models adjusting for age, smoking, and physical activity, increased risks for diabetes were observed in the normal weight with metabolic syndrome (odds ratio 3.28 [95% CI] 1.38-7.81; P = 0.007), overweight without metabolic syndrome (3.49 [2.26-5.42]; P < 0.001), overweight with metabolic syndrome (7.77 [4.44-13.62]; P < 0.001), obese without metabolic syndrome (11.72 [4.88-28.16]; P < 0.001), and obese with metabolic syndrome (10.06 [5.19-19.51]; P < 0.001) categories compared with the normal weight without metabolic syndrome category. CONCLUSIONS: Overweight or obese men without metabolic syndrome were at increased risk for diabetes. Our data provide further evidence that overweight and obesity in the absence of the metabolic syndrome should not be considered a harmless condition.