Exposure over the life course to an urban environment and its relation with obesity, diabetes, and hypertension in rural and urban Cameroon

BACKGROUND: This study aimed to assess the association between lifetime exposure to urban environment (EU) and obesity, diabetes, and hypertension in an adult population of Sub-Saharan Africa. METHODS: We studied 999 women and 727 men aged > or =25 years. They represent all the adults aged > or =25 years living in households randomly selected from a rural and an urban community of Cameroon with a 98% and 96% participation rate respectively. Height, weight, blood pressure, and fasting blood glucose were measured in all subjects. Current levels of physical activity (in metabolic equivalents MET) were evaluated through the Sub-Saharan African Activity Questionnaire. Chronological data on lifetime migration were collected retrospectively and expressed as the total (EUt) or percentage (EU%) of lifetime exposure to urban environment. RESULTS: Lifetime EUt was associated with body mass index (BMI) (r = 0.42; P < 0.0001), fasting glycaemia (r = 0.23; P < 0.0001), and blood pressure (r = 0.17; P < 0.0001) but not with age. The subjects who recently settled in a city (< or =2 years) had higher BMI (+2.9 kg/m(2); P < 0.001), fasting glycaemia (+0.8 mmol/l; P < 0.001), systolic (+23 mmHg; P < 0.001) and diastolic (+9 mmHg; P = 0.001) blood pressure than rural dwellers with a history of 2 years EU. EU during the first 5 years of life was not, on its own, associated with glycaemia or BMI. However, both lifetime EUt and current residence were independently associated with obesity and diabetes. The association between lifetime EUt and hypertension was not independent of current residence and current level of physical activity. CONCLUSIONS: This study suggests that for the study of obesity and diabetes, in addition to current residence, both lifetime exposure to an urban environment and recent migration history should be investigated.