Prevalence of glucose intolerance and associated risk factors in rural and urban populations of different ethnic groups in Kenya

The study team is indebted to the late Benedict Omondi for planning and coordinating laboratory analysis.
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Abstract

Objective

To assess the prevalence of glucose intolerance in rural and urban Kenyan populations and in different ethnic groups. Further, to identify associations between lifestyle risk factors and glucose intolerance.

Research design and methods

A cross-sectional study included an opportunity sample of Luo, Kamba, Maasai, and an ethnically mixed group from rural and urban Kenya. Diabetes and IGT were diagnosed using a standard OGTT. BMI, WC, AFA, AMA and abdominal subcutaneous and visceral fat thicknesses, physical activity and fitness were measured. Questionnaires were used to determine previous diabetes diagnosis, family history of diabetes, smoking habits, and alcohol consumption.

Results

Among 1459 participants, mean age 38.6 years (range 17–68 years), the overall age-standardized prevalence of diabetes and IGT was 4.2% and 12.0%. The Luo had the highest prevalence of glucose intolerance among the rural ethnic groups. High BMI, WC, AFA, abdominal visceral and subcutaneous fat thickness, low fitness and physical activity, frequent alcohol consumption, and urban residence were associated with glucose intolerance.

Conclusions

The prevalence of diabetes and IGT among different Kenyan population groups was moderate, and highest in the Luo. The role of lifestyle changes and ethnicity on the effect of diabetes in African populations needs further exploration.

Introduction

The first study attempting to estimate the diabetes prevalence in an African population was carried out in 1958 finding a very low prevalence of 0.4% among urban children and adults in Ghana [1]. For the following three decades, prevalence of <3.0% was found in rural and urban participants [2], [3], [4], except for studies carried out in South Africa, where a prevalence of 3.6% was found [5]. However, glycosuria was used for screening in most of these early studies, which led to underestimated prevalence rates of diabetes since glycosuria has a low sensitivity as a screening tool [6]. In 1993, an age-adjusted diabetes prevalence of 8.0% in urban South Africans [7] using oral glucose tolerance test (OGTT) was reported, and recently a prevalence of 6.8% was found among urban Nigerians [8]. The latter studies have indicated the beginning of a diabetes epidemic in sub-Saharan Africa (SSA), even though a prevalence of just 0.3% in rural and urban Gambians was found as late as 1997 [9], showing that considerable regional variation continue to exist within the African continent.

A rural-urban difference in diabetes prevalence was shown in Tanzania [10], but could not be verified in rural vs. urban populations in Cameroon [11]. Thus, environmental factors may not affect different populations to the same extent when it comes to blood glucose dysregulation.

Thus, the aim of the present study was to investigate the impact of urbanisation and ethnicity on the prevalence of diabetes and impaired glucose tolerance (IGT) in Kenyan populations and to identify the major risk factors for developing glucose intolerance.

Section snippets

Study area and population

A cross-sectional study in Kenya was conducted among three rural populations – the Luo, Kamba, and Maasai – and in an urban population of mixed ethnic origin. The Luo are subsisting on mainly cereal foods as staple foods supplemented with fish, the Kamba on cereal foods and tubers, and the Maasai on animal husbandry and maize [12].

Selection procedure

Inclusion criteria for the study were age ≥17 years and Luo, Kamba or Maasai ethnicity in the rural areas and the same ethnicities or biologically and culturally

Results

Mean age of the participants was 38.6 years (range 17–68 years). Of 1486 individuals who initially agreed to participate, 1459 (98.2%) completed the study. Of these, 1178 (80.7%) were rural participants, and 281 (19.3%) were urban participants, and 58.0% were females.

Background characteristics for rural and urban populations are presented in (Table 1). Of the 1459 participants examined, 200 (13.7%) met the criteria for glucose intolerance, including 59 individuals with diabetes (4.1%). The

Discussion

We found a relatively low age-standardised prevalence of diabetes of 4.2% with a concurrent high prevalence of IGT of 12.0% in selected Kenyan population groups. The prevalence of diabetes and IGT was highest in the urban population, which is in line with several [10], [17], but not all [11] studies from SSA. However, due to differences in methodology, comparisons with other studies conducted in the region are difficult. Few have been based on an OGTT or have calculated age-standardised

Conflict of interest

There are no conflicts of interest.

Acknowledgement

We are grateful to all participants, the local chiefs and sub-chiefs, the local elder councils and district politicians. We are also indebted to laboratory technicians Tobias Oketch (CVBCR), Arthur J. Ukumu (DVBD), Odero Sabiano (DVBD) and Saidi Kisiwa (KEMRI) for skilful collection and analysis of blood samples in the field. Likewise, we owe our sincere thanks to Filista Kingori of KEMRI for collecting health assessment data, and we thank Dr. Søren Brage, MRC Epidemiology Unit, Cambridge, UK,

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