Glucose intolerance in an urban male community in Saudi Arabia
Most chronic non-communicable diseases result from a complex interaction between heredity and environmental factors. With better living conditions and adoption of western lifestyles in developing countries, there is an increased incidence of these diseases, the most common of which is diabetes. This study documents the prevalence of NIDDM, lOT, hypertension, obesity and hyperlipidaemia in an urban male community [n= 125] in Jeddah, Saudi Arabia. It also examines OGl'T reproducibility [n=35]; the influence of diet and physical activity; the differences in these aspects between nationals and non-nationals and the metabolic responses following the OGTT between the glucose tolerance groups [n=43]. Glucose intolerance, NIDDM [14%] and ICiT [27%], were very common. Overall, CVD risk factors such as smoking [43%], obesity [29%], hypertension [5%], hypercholesterolaemia [7%], hypertriglyceridaemia [14%], occurring in association with diabetes were high. Clustering of other risk factors such as abdominal obesity, hyperinsulinaemia and hyperproinsulinaemia were also shown. The OGTT is a poorly reproducible test in this community and a further confirmatory test is always required to establish the diagnosis of glucose intolerance. The dietary habit and food item record identified recognizable features characteristic of this community, which were affected by both the cultural and the social background. However, no differences were found between the glucose tolerance groups. Physical inactivity was a major lifestyle problem and the inactive group tended to have increased risk factors, although differences were not significant. These environmental factors could not, however, be excluded as possible causative factors in the high prevalence of glucose intolerance and CVD risk factors in this community as the sample was small. Subjects with 101' tended to have intermediate levels of risk factors and this study favours identifying IGT as an independent category which lies between normal and NIDDM. Ethnic differences should be considered whenever possible particularly in this multinational community, since 40 % of this community were non-nationals. Nationals differed in certain dietary aspects and they tended to be inactive, otherwise no other significant differences existed between the groups. As shown in different populations, those identified as ICT or NIDDM in this community, were characterised by hyperfunction of the a-cell in IGT, hypofunction of the a-cell in NIDDM and associated with immature secretion of proinsulin. The insulin resistance which was profound in NIDDM and intermediate in TOT was characterised by high glycerol and NEFA which were suggestive of insulin insensitivity at the level of adipose tissue. Large-scale and prospective studies are strongly recommended. Meanwhile, primary prevention measures are urgently required as these findings pose a significant public health problem.