Self-reported incident type 2 diabetes in the Ibadan study of ageing: relationship with urban residence and socioeconomic status

Background: There is no incident study of diabetes among elderly Nigerians and it is unclear what factors may constitute risks for the condition in this society undergoing rapid social changes.

Objective: This study explores the link between urban residence and socioeconomic status, and incident diabetes among community-dwelling elderly Nigerians.

Methods: A cohort of 2,149 persons, aged 65 years and above, were recruited through a clustered multistage sampling in eight contiguous predominantly Yoruba-speaking states in south-western and north-central regions of Nigeria. Follow-up evaluation was conducted approximately 39 months after the baseline assessments. Face-to-face assessments obtained self-report of chronic medical conditions, including diabetes, using a standardized checklist as well as information on social factors, including residence. Incident diabetes was determined among persons who were free of the problem at baseline (n = 1,330).

Results: At follow-up, 38 subjects had developed diabetes giving an incidence rate of 8.87% [95% confidence interval (CI): 6.45-12.19] per 1,000 person-years. A stepwise relationship was found between incident diabetes and urbanicity as well as increasing economic status. The highest incidence of diabetes (13.57%; 95% CI: 8.75-21.03 per 1,000 person-years) occurred among subjects residing in urban areas, representing an adjusted relative risk of 4.25 (95% CI: 1.81-9.94) compared to those residing in rural areas. Also, compared with persons in the lowest economic group, those in the highest group had about a 3-fold elevated risk of having incident diabetes.

Conclusion: Urban residence and increasing socioeconomic status are risk factors for new onset diabetes among elderly Nigerians. These social factors may be proxies for lifestyles that increase the likelihood of developing the disorder.