Weight history, low birth weight, alcohol consumption and type 2 diabetes

Abstract: Type 2 diabetes is an increasing public health problem, currently affecting about 3-4% of the Swedish population. A worldwide increase in the prevalence of the disease has been demonstrated and preventive strategies are needed to turn this trend. Better knowledge about etiologic factors may lead to more specific intervention and prevention of the disease. The aim of this thesis was to contribute to this knowledge by investigating the association between type 2 diabetes and weight history, low birth weight and alcohol consumption. Analyses were based on a cross-sectional study consisting of 3128 middle-aged men of whom 50% had diabetes in close relatives (Stockholm Diabetes Prevention Program (SDPP). During a health examination, 55 cases of type 2 diabetes and 172 cases of impaired glucose tolerance (IGT) were identified by oral glucose tolerance test. In addition, information on previous weight, birth weight, alcohol consumption and other lifestyle factors were obtained by questionnaire. Analyses of alcohol and type 2 diabetes were also performed in a large prospective study based on the Finnish Twin Cohort. This Cohort was compiled in 1974 and consists of about 16,000 twin pairs. In 1975, 1981 and 1990, subjects were investigated by questionnaire on health and lifestyle factors, including alcohol. By record linkage to registers of hospital discharge and prescribed medication we identified incident cases of diabetes 1976- 1995. A clinical study performed within the Cohort was used to investigate the validity of questionnaire information on alcohol. In this study, information on alcohol by questionnaire, by interview and through three biochemical indicators of alcohol intake; CDT, gamma-GT and MCV was obtained for a sub-sample of 76 twin pairs. The results indicated that the prevalence of type 2 diabetes and impaired glucose tolerance increases with duration of obesity. The odds ratio (OR) of diabetes associated with a short (<5 years) and long (>=10 years) duration of overweight (BMI >25.0 kg/M2) was estimated at 1.9 (95% confidence interval (Cl)=0.5-7. 1) and 7.3 (95% CI=2.2-23.7), respectively. Low birth weight (<3000g) was associated with an increased prevalence of diabetes (OR=4.5, 95% CI=1.9-10.8) and of IGT (OR=1.9, 95% CI=1.0-3.4) after adjustment for family history of diabetes. A particularly high prevalence of diabetes was seen in men with a family history of diabetes in combination with low birth weight, (OR= 10.9 (95% C1=2.9-41.2). Results from SDPP and from the Finnish Twin Cohort were compatible with a reduced risk of diabetes in moderate consumers of alcohol among men, (OR=0.7, 95% CI=0.3-1.8), and RR=0.7 (95% CI=0.5-1.1), respectively. High alcohol intake was associated with an increased prevalence of diabetes in men of SDPP (OR=2.1 (95 % CI=1.0-4.5) but not in the Finnish Twin Cohort. Binge drinking in women of the Finnish Twin Cohort was associated with an increased risk (RR=2.1, 95% CI=1.0-4.4). Comparison of questionnaire information on alcohol to dietary interview information and biochemical indicators indicated that the questionnaire had a rather low sensitivity but high specificity for identification of high consumers. In conclusion, the results of this thesis suggest that a long duration of obesity is an important risk factor for type 2 diabetes in addition to degree and distribution of obesity. The results are consistent with previous studies indicating that low birth weight is associated with type 2 diabetes and expands current knowledge by showing that this association is not explained by family history of diabetes. However, men with the combination of low birth weight and family history of diabetes may be particularly prone to develop the disease. Results from this thesis also provide support for the hypothesis that moderate alcohol consumption reduces the risk of type 2 diabetes.