Risk of dementia associated with body mass index, changes in body weight and waist circumference in older people with type 2 diabetes: The Edinburgh Type 2 Diabetes Study

Abstract

AbstractAims/HypothesisTo determine the relationship of dementia with preceding body mass index (BMI), changes in body weight and waist circumference in older people with type 2 diabetes.MethodsIn the Edinburgh Type 2 Diabetes Study (1064 men and women with type 2 diabetes, aged 60–75), body weight, waist circumference and BMI were measured at baseline and after 4 years in a subgroup (n = 821). Percentage body weight and waist circumference change over 4 years were calculated. Data on incident dementia was recorded during a median follow‐up time of 10.84 years. Survival models considering a range of co‐variables and/or death as a competing risk were used to estimate the risks of dementia associated with each weight‐related variable.ResultsA total of 105 incident dementia events were recorded. When compared with people in the lowest BMI group (<25 kg/m2), risk of dementia was lower in intermediate BMI groups (25–29.9 kg/m2, HR 0.44, p = 0.002; 30–34.9 kg/m2, HR 0.41, p = 0.001) and the highest BMI group (≧35 kg/m2, HR 0.35, p = 0.001). In the weight change subgroup, 78 incident dementia events were recorded between years 4 and 10. Body weight loss over 5% (compared with ≦5%) was associated with higher incidence of dementia (HR 2.06, p = 0.010). The association between waist circumference change and dementia was not significant.Conclusions/InterpretationsBoth a lower BMI and weight loss over a period of years are indicative of increased dementia risk for older people with type 2 diabetes, while waist circumference changes may be less informative.