This investigation was undertaken to study whether the risk to develop non-insulin-dependent diabetes mellitus (NIDDM) among 50-year-old men during a 10-year follow-up period was related to the fatty acid composition of their serum cholesterol esters. There were highly significant differences in the initial health survey between the fatty acid composition in serum in subjects who remained normoglycemic (n = 1,753) and in those who later developed NIDDM (n = 75). The main differences were that the latter had higher proportions of saturated fatty acids and palmitoleic acid (16:1 omega-7), a low proportion of linoleic acid (18:2 omega-6), and a relatively high content of gamma-linolenic (18:3 omega-6) and dihomo-gamma-linolenic (20:3 omega-6) acids in the serum cholesterol esters. The picture was similar also after adjusting for differences in body mass index. In a logistic model, a high proportion of dihomo-gamma-linolenic acid remained a significant contributor to the development of diabetes, along with the height of the insulin index, the blood glucose concentration at 60 min, and the fasting insulin concentration. The increased risk to develop NIDDM related to the serum cholesterol ester fatty acid composition may be mediated by diet and/or genetic factors.
Experimental evidence suggests a specific role for the active metabolite of vitamin D (1,25(OH)2D3) in insulin secretion. In order to evaluate the possible clinical significance, 65 middle‐aged men with impaired glucose tolerance, and normal serum levels of vitamin D metabolites, were enrolled in a three‐month study where they were given either 0.75 μg alpha‐calcidol (1α(OH)D3) daily or placebo. Indices of glucose and lipid metabolism were evaluated before and after treatment. There were no significant changes during the trial neither for fasting blood glucose, hemoglobin A1C or for the intravenous glucose tolerance between the treatment and the placebo groups, nor were there any consistent changes in insulin values during the glucose tolerance test. Subjects treated with alpha‐calcidol displayed a significant reduction in body weight with an average of 1.1. kg, while those receiving placebo lost no weight. Treatment did not affect the serum lipoprotein values. Thus, a modest dose of active vitamin D, which did not cause elevation of serum calcium, did not provide general improvement of glucose tolerance or of insulin secretion when given to patients with impaired glucose tolerance, but without vitamin D deficiency, over a three‐month period.
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