Capillary basement membrane changes in adolescents with type 1 diabetes.

Measurements were made of muscle capillary basement membrane thickness (CBMT) in 95 normal boys and girls and 167 postpubescent insulin-dependent diabetics. Of 110 diabetics in whom "higher" degrees of metabolic control were maintained, only two had increased CBMT values. Of 57 diabetics in whom "lower" degrees of metabolic control were maintained, 26 had increased CBMT values. Two or more muscle biopsies were done in each of 65 diabetic subjects: Mean CBMT values of 24 subjects with "higher" degrees of metabolic control for two to nine years remained within the normal range; values of 23 subjects with "lower" degrees of metabolic control for only one to three years increased from 858 +/- 142 A to 1,155 +/- 227 A: values of 13 subjects who had been in "lower" degrees of control decreased from 1,255 +/- 232 A to 869 +/- 135 A after maintaining "improved" metabolic control for about a year. In postpubescent diabetics, the CBMT is labile and progresses or regresses depending on the degree of metabolic control.