• Type 2 diabetes mellitus is strongly associated with obesity. More than 80 percent of cases of type 2 diabetes can be attributed to obesity.
  • There is a curvilinear relationship between BMI and the risk of type 2 diabetes. Lowest risk is associated with a BMI below 22 kg/m2
  • At a BMI greater than 35 kg/m2, the relative risk for diabetes adjusted for age increases to 61. The risk may further increase by a sedentary lifestyle or decrease by exercise.
  • Weight gain after age 18 years in women and after age 20 years in men increases the risk of type 2 diabetes.
  • The Nurses’ Health Study compared women with stable weight (those who gained or lost <5 kg) after the age of 18 years to women who gained weight. Those who had gained 5.0 to 7.9 kg had a relative risk of diabetes of 1.9; this risk increased to 2.7 for women who gained 8.0 to 10.9 kg.
  • Similar findings were noted in men in the Health Professionals Study. The excess risk for diabetes with even modest weight gain is substantial.
  • Weight gain precedes the onset of diabetes. Among Pima Indians (a group with a particularly high incidence of type 2 diabetes), body weight gradually increased 30 kg (from 60 kg to 90 kg) in the years preceding the diagnosis of diabetes. Conversely, weight loss is associated with a decreased risk of type 2 diabetes.
  • Insulin resistance with high insulin levels is characteristic of obesity and is present before the onset of high blood sugar levels.
  • Obesity leads to impairment in glucose removal and increased insulin resistance, which result in hyperinsulinemia. Hyperinsulinemia contributes to high lipid levels and high blood pressure.