Capillary basement membranes in muscle in glucose intolerance of the chemical diabetes type

Enzyme activities as a predictor of diabetic vasculopathy

Forty-one patients with chemical diabetes had three oral glucose tolerance tests and underwent muscle biopsy three times over a period of three years. Twenty-three received glipizide and 18 placebo. Those taking placebo had an increase in the mean muscle capillary basement membrane width (p = 0.01), but those taking glipizide showed a decrease (p = 0.01) to values no different from those of nondiabetic subjects. Determinations of enzyme activities involved in the synthesis and degradation of glycoproteins revealed a three-year decrease (not significant) in muscle glucosyltransferase activity in the glipizide-treated patients, but a statistically significant difference (p less than 0.01) comparing the adjusted means of the two treatment groups. N-acetyl-beta-glucosaminidase activity was significantly increased in muscle from baseline values (p less than 0.01), with adjusted means also significantly different (p less than 0.01). The data suggest that changes in basement membrane and enzyme activities are correlated, and the latter may be a predictor to follow the development, progression, or regression of diabetic vasculopathy.

Overview article: basal lamina of epidermis, muscle fibers, muscle capillaries, and renal tubules: changes with aging and in diabetes mellitus

Using autopsy material from 14 diabetics and 10 controls (8-84 years old), the authors measured the thickness of basal lamina (BL) in skeletal muscle capillaries, renal tubules, skeletal muscle fibers, and epidermis to determine whether BL accumulation is a generalized phenomenon or limited only to certain anatomic structures. The four structures were selected because earlier experiments in animals have shown that in two (muscle capillaries and renal tubules) BL accumulates as a by-product of cell renewal while in the other two (muscle fibers and epidermis) it does not. In human tissues we found that BL accumulates in muscle capillaries and renal tubules but not in muscle fibers and epidermis, in muscle capillaries and in renal tubules it accumulates in controls and in diabetics as a function of aging, more BL in both anatomic structures accumulates in diabetics than in controls, and the extent of BL accumulation in muscle capillaries and renal tubules does not correlate with duration of diabetes mellitus. In addition to the fact that BL does not accumulate in all anatomic structures in which BL is normally present, the observations indicate that diabetes alone is not responsible for BL accumulation, diabetes exaggerates age-dependent accumulation of BL, and accumulation of BL in man is probably a by-product of cell renewal.

Diabetic regulation and its relationship to microangiopathy

This review addresses the question of the effectiveness of rigid regulation of the blood glucose in delaying or preventing the vascular complications of diabetes mellitus. Morphometric, pathologic, biochemical, and clinical evidence on both sides of this question are presented. It is concluded that because of present inadequate methods of completely returning glucose homeostasis to normal in diabetics, the question remains moot.