Hyperglycemia, Type 2 Diabetes, and Depressive Symptoms The British Whitehall II study

OBJECTIVE - To examine the recent suggestion that impaired fasting glucose may protect against depression, whereas a diagnosis of diabetes might then result in depression. RESEARCH DESIGN AND METHODS - Cross-sectional analysis of 4,228 adults (mean age 60.7 years, 73.0% men) who underwent oral glucose tolerance testing and completed the Center for Epidemiologic Studies Depression scale (CES-D). RESULTS - After adjustment for demographic factors, health behaviors, and clinical measurements (BMI, waist circumference, lipid profile, and blood pressure), there was a U-shaped association between fasting glucose and depression (P-curve = 0.001), with elevated CES-D at low and very high glucose levels. This finding was replicable with 2-h postload glucose (P = 0.11) and AlC (P = 0.007). CONCLUSIONS - The U-shaped association between blood glucose and CES-D, With the lowest depression risk seen among those in the normoglycemic range of AlC, did not support the hypothesized protective effect of hyperglycemia.