Plasma copeptin and the risk of diabetes mellitus.

BACKGROUND: Animal studies suggest that the arginine vasopressin system may play a role in glucose metabolism, but data from humans are limited. METHODS AND RESULTS: We analyzed plasma copeptin (copeptin), a stable C-terminal fragment of the arginine vasopressin prohormone. Using baseline and longitudinal data from a Swedish population-based sample (n=4742; mean age, 58 years; 60% women) and multivariable logistic regression, we examined the association of increasing quartiles of copeptin (lowest quartile as reference) with prevalent diabetes mellitus at baseline, insulin resistance (top quartile of fasting plasma insulin among nondiabetic subjects), and incident diabetes mellitus on long-term follow-up. New-onset diabetes mellitus was ascertained through 3 national and regional registers. All models were adjusted for clinical and anthropometric risk factors, cystatin C, and C-reactive protein. In cross-sectional analyses, increasing copeptin was associated with prevalent diabetes mellitus (P=0.04) and insulin resistance (P<0.001). During 12.6 years of follow-up, 174 subjects (4%) developed new-onset diabetes mellitus. The odds of developing diabetes mellitus increased across increasing quartiles of copeptin, even after additional adjustment for baseline fasting glucose and insulin (adjusted odds ratios, 1.0, 1.37, 1.79, and 2.09; P for trend=0.004). The association with incident diabetes mellitus remained significant in analyses restricted to subjects with fasting whole blood glucose <5.4 mmol/L at baseline (adjusted odds ratios, 1.0, 1.80, 1.92, and 3.48; P=0.001). CONCLUSIONS: Elevated copeptin predicts increased risk for diabetes mellitus independently of established clinical risk factors, including fasting glucose and insulin. These findings could have implications for risk assessment, novel antidiabetic treatments, and metabolic side effects from arginine vasopressin system modulation.