Background: Increased adiposity is associated with increased cardiovascular disease (CVD) risk but among overweight individuals clarification is needed of relationships between insulin sensitivity, fat distribution and metabolic health that might contribute to this risk.
Methods: During the Heart Disease and Diabetes Research Indicators in a Screened Cohort (HDDRISC) study, 560 employment cohort normoglycaemic (FPG less than 7 mmol/L) Caucasian men (mean age 49.9 years, BMI 25.4 kg/m2) received measurements of insulin sensitivity, Si, by IVGTT minimal model analysis. High or low insulin sensitivity was defined according to whether the value for Si was, respectively, above or below the median . Measurements of Si plus DXA body fat and CVD risk factors were recorded for 272 participants . Overweight was defined according to the cohorts BMI distribution and its associated CVD mortality risks. DXA and risk factor characteristics in overweight participants were compared between those with higher or lower Si.
Results: Median Si was 3.0 min−1.mU−1.L and BMI≥27 kg/m2 was considered overweight. Of the 272 potential participants, 78 were overweight (median BMI 28.8, interquartile range 27.7-30.5 kg/m2) with 55 located in the lower Si and 23 in the higher Si groups. The two groups did not differ in age, BMI, blood pressure, total cholesterol, uric acid, FPG, smoking, exercise, alcohol or medication. The higher Si group had lower median LDL cholesterol (3.13 vs 3.47 mmol/L, P=0.008) and, triglycerides (1.19 vs 2.22 mmol/L, P=0.003) and higher HDL cholesterol (1.30 vs 1.12 mmol/L, P=0.02). DXA fat masses did not differ between the groups but the higher Si group had a lower percentage of android fat (53.0 vs 56.4%, P=0.03).
Conclusions: In overweight Caucasian men, there is marked variation in insulin sensitivity, with higher insulin sensitivity associated with lower percent android fat and a more favourable CVD risk factor profile. This heterogeneity supports differentiation of metabolically healthy and unhealthy overweight and obesity.