The prevalence of impaired glucose tolerance and diabetes amongst the middle aged population of Bellville South community, Cape Town, South Africa

Abstract

Numerous sources including the World Health Organization (WHO) and International Diabetes Federation (IDF) reported that a diabetes epidemic, with a parallel rise in obesity and insulin resistance is presently enveloping the world. Type 2 diabetes mellitus accounts for over 80% of all diabetics in most countries and has been recognized as a global epidemic, with its prevalence increasing at a rapid rate in both developed and developing countries. Up to 80% of type 2 diabetic cases can be preventable by changing diet, increasing physical activity and improving the living environment. The prevalence of diabetes in South Africa varies from one province to another and within different population groups. The highest rates have been reported among Asian Indians and the mixed ancestry populations, however, data is limited. Urbanization and industrialization which come along with westernized lifestyles such as sedentarism, consumption of high fat diets consequently resulting into obesity are some of the factors implicated in the development of type 2 diabetes. With type 2 diabetes prevalence rate increasing at an alarming rate, both in industrialized and also in developing countries, every factor associated with the development of diabetes needs to be explored and addressed. Before progression to diabetes, the diabetic state is preceded by a glucose regulation disorder commonly referred to as impaired glucose tolerance which may last for several years. Another form of glucose metabolism disorder other than diabetes is impaired fasting blood glucose level. While some cases of diabetes are often undiagnosed, it has also been noted that for every one diagnosed diabetic, there could be another that is undiagnosed. As has been shown in this study, many people could be walking with diabetes which is undiagnosed. The aims of this study were to determine: The prevalence of impaired fasting glucose (IFG), impaired glucose tolerance (IGT), diabetes mellitus and the risk factors for developing diabetes amongst the 35 – 65 year old population of Bellville South, Cape Town South Africa. In a cross-sectional survey, 600 subjects within the age group of 35-65 years selected through stratified random sampling within the Bellville South area of Cape Town

underwent an oral glucose tolerance test. Diabetes, IGT and IFG were determined using both the American Diabetes Association (ADA) and the revised WHO criteria. Subjects also underwent several anthropometric measurements. Personal demographic, family, health and lifestyle data were extrapolated by use of a questionnaire. The prevalence of diabetes did vary between the two criterion used. The prevalence of newly diagnosed diabetes was 77 (12.8%) using the WHO criteria and 62 (10.3%) using the ADA criteria. Overall, the prevalence of diabetes was 25.6 % of which 12.8 % were newly diagnosed. IGT was present in 24 (4.0%) whilst IFG was in 179 (29.8%) using the WHO and ADA criterion respectively. Females were more affected than males and the prevalence of diabetes increased with age. Although overweight did not differ significantly between males and females, the latter were significantly more obese across all age groups (p < 0.05). Presence of a first degree relative with diabetes mellitus, particularly the father was significantly associated with development of diabetes, (odds ratio = 2.092, 95% CI 1.109 – 3.949, p = 0.023). Though more than 40% of the population studied was shown to engage in heavy drinking (30g of alcohol per day), it was not associated with diabetes. There has been a 10.4% increase in the prevalence of diabetes in this population group compared to what was reported more than a decade ago. Of great concern is the number of individuals with undiagnosed diabetes.