Elevations of metabolic risk factors 20 years or more before diagnosis of type 2 diabetes: Experience from the AMORIS study

AIMS:To describe trajectories for metabolic risk factors for type 2 diabetes (T2D) up to 25 years prior to diagnosis and to estimate the absolute 20-year risk for T2D based on a simple set of commonly measured key risk factors. METHODS:From the Swedish AMORIS cohort we included 296 428 individuals with data on fasting glucose obtained in health examinations during 1985-1996 (baseline period). All participants were followed until 2012 for development of incident T2D. The 20-year T2D risk based on age, sex, body mass index (BMI), fasting glucose and triglycerides was estimated. Trajectories for biomedical risk factors of T2D starting from >20 years before diagnosis and including fasting glucose, triglycerides and BMI were evaluated according to yearly means for cases and controls. RESULTS:We identified 28 244 new T2D cases during the study period, with an average 20-year risk of 8.1%. This risk was substantially increased in overweight and obese participants and those with elevated fasting glucose and triglyceride levels, in both men and women. T2D cases had higher mean BMI and fasting glucose and triglyceride levels compared with controls >20 years before diagnosis and the difference in fasting glucose levels increased over time. CONCLUSIONS:Development of T2D is associated with subtle elevations in glucose and lipid levels >20 years before diagnosis. This suggests that diabetogenic processes tied to chronic insulin resistance operate for decades prior to the development of T2D. A simple risk classification can help in early identification of individuals who are at increased risk.