Family history of diabetes identifies a group at increased risk for the metabolic consequences of obesity and physical inactivity in EPIC-Norfolk: a population-based study

OBJECTIVE: To investigate the interaction of a family history of diabetes with obesity and physical inactivity on diabetes prevalence in middle-aged and elderly men and women. DESIGN: A cross-sectional population-based study. SUBJECTS: 2912 men and 3561 women, aged 45-74 y. MEASUREMENTS: Body mass index (BMI), HbA(1C), self-administered questionnaire including questions on occupational physical activity and personal and family history of diabetes as part of the Norfolk arm of the European Prospective Investigation into Cancer (EPIC-Norfolk). RESULTS: The prevalence of diabetes increased in a dose-response relationship with increasing BMI, There was an interaction between family history and obesity on diabetes risk in subjects with a BMI of greater than 27.5 kg/m(2) (P = 0.049), Crude prevalence in individuals without a family history and BMI of 22.5 - 24.9 kg/m(2) was 2.2% compared to 33.3% in those with a family history and BMI over 35 kg/m(2). Thirty-eight percent of the excess risk of diabetes in people with a family history could be avoided if their BMI did not exceed 30 kg/m(2). Individuals who reported sedentary occupations were at greater risk of diabetes compared to those reporting more active occupations. There was a synergistic effect of family history and self-reported occupational physical activity on diabetes risk. CONCLUSION: Individuals with a family history of diabetes are at increased risk for the metabolic consequences of obesity and form an easily identifiable group who may benefit from targeted intervention to prevent the development of obesity through increased physical activity.