Serum Lipid Level in Japanese Diabetics

II. Comparative Study between Urban and Rural Area

Abstract

It is well known that serum lipid levels vary depending upon regional conditions, such as different dietary habits or certain environmental factors. The present study was conducted to find possible factors influencing regional differences in the relation between serum lipid levels and diabetic vascular complications.
The subjects studied were 237 inhabitants of No-se Town, a rural mountainous agricultural area located about 40km North of Osaka City. They were given GTT at a diabetes mass survey and were given a follow-up examination 7 years later. The 2, 383 subjects who were dealt with in the preceeding report were used as controls. These latter were mostly inhabitants of the urban area of Osaka and its adjacent cities.
For both sexes the serum cholesterol level was higher in the urban subjects than in the rural subjects. It was higher in females than in males in both urban and rural subjects.
Although the serum triglycerides level, was higher in urban males than rural males, rural females revealed a higher level than urban females. For both regional groups, diabetics had a clearly higher incidence of hypertriglyceridemia.
The correlation between cholesterol and triglyceride levels, which was significant in the urban series, was not significant for the rural series. This suggests a different pattern of distribution of the two lipids.
The incidence of hypertension was higher in the rural subjects but that of coronary heart disease was higher in the urban subjects. Thus it can be concluded that, though there is a clear relationship between cholesterol and coronary heart disease, triglycerides play little part in the development of coronary heart disease, because hypertriglyceridemia was more frequent in rural females.
It was also observed that the cholesterol level in No-se significantly increased over the past seven years, because of the change in socioeconomical conditions.
A partial correlation analysis indicated that the cholesterol level was related to FBS, and that the triglyceride level was related to obesity and FBS, but not to ECG scores (CHD). In an analysis of principal components, the variables were classified into three groups ; The first related to glucose metabolism, the second to hypertensive changes, and the third to the lipid metabolism. ECG scores were closely related to hypertensive changes but not to cholesterol or to triglycerides.
As a conclusion, the lipid metabolism in diabetics was primarily attributable to a geographical factor, being modified by glucose metabolism as a secondary factor. No significant effect of hyperlipemia on diabetic vascular complications was found.