Prevention of type 2 diabetes by lifestyle intervention: a Japanese trial in IGT males
Introduction
Primary prevention of type 2 diabetes mellitus has been attracting a great deal of interest recently [1], [2], [3], because a dramatic increase in the number of diabetic patients in the world portends a serious problem in the future. Type 2 diabetes is on the rise throughout the world, and it is estimated that the number of cases of diabetes will be doubled in the 15 years from 1995 to 2010 [4]. It was about 100 million in 1994, and is expected to be 230 million in 2030 [5]. Its prevalence in adults was 4.0% in 1995 and is expected to increase to 5.4% in 2025 [6]. The increase in diabetes is particularly striking in developing countries, but there has also been a steady increase in developed countries such as in the United States and Japan [7], [8].
Despite progress in methods of treating diabetes, vascular complications, both microangiopathy and macroangiopathy, are common, and they are important causes of morbidity and mortality in diabetic patients [9], [10]. Diabetes is becoming a major burden on the national health care expenditure [11], and it is no wonder that WHO stresses the importance of preventing diabetes [12]. Several trials have shown a beneficial effect of intervention by lifestyle manipulation or drug therapy in persons with impaired glucose tolerance (IGT) in decreasing the incidence of type 2 diabetes [13], [14], [15], [16].
Type 2 diabetes has also been increasing in Japan, where its prevalence increased by six- to seven-fold over the past 30 years [17]. Japanese people have been the least obese in developed countries, but their mean body mass index (BMI) is tending to gradually increase [18], and the increase in type 2 diabetes is a concern.
Since 1984 we have been following subjects with mild abnormalities of glucose metabolism detected by screening in a general health checkup program, and they have been examined regularly by repeated oral glucose tolerance tests (OGTT) [19], [20]. In this paper, we report that the development of diabetes can be significantly prevented by intervention in lifestyle designed to achieve and maintain the ideal body weight of each individual during an observation period of 4 years in subjects with IGT.
Section snippets
Subjects
Since 1983 the Health Medical Center in Toranomon Hospital has been conducting a health-screening program, mostly for government employees. We randomly selected subjects with a fasting plasma glucose (FPG) value below 140 mg/dl and a 2-h plasma glucose (2hPG) value after a 100 g glucose load of between 160 and 239 mg/dl on 100 g OGTTs from among examinees in 1990–1992. This 2hPG level roughly corresponds to the 140–199 mg/dl range on the 75 g OGTT, and thus the subjects had IGT according to the WHO
Baseline characteristics and follow-up
Table 1 shows the baseline characteristics of the control group and the intervention group. Body mass index (BMI), history for diabetes among first-degree relatives, prevalence of low early insulin response on the OGTT (ΔIRI/ΔPG (30 min) <0.5 μU/ml/mg/dl), and serum triglyceride, total cholesterol, and HDL-cholesterol levels, did not differ significantly between the two groups. The plasma glucose and insulin levels during the 100 g OGTT were very similar in the control and intervention groups (
Discussion
Individuals with IGT are a high-risk group for the development of type 2 diabetes. In this study males with IGT were selected to assess the effect of lifestyle intervention on the incidence of diabetes. The intervention was individualized according to the current lifestyle of each subject and was designed to achieve and maintain the optimal BMI by appropriately adjusting the amount and composition of meals and increasing physical activity. Lifestyle intervention resulted in significant
Acknowledgments
The authors are grateful to Dr. Akihiro Isogawa for technical assistance in the statistical analyses.
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