Variation in thickness of the capillary basement membrane in single muscles of diabetic subjects.

Thickness of skeletal muscle's capillary basement membrane was measured in gastrocnemius and quadriceps femoris muscles of diabetic subjects. At least two different sites of each muscle studied were biopsied. Comparison of these biopsy samples revealed a marked and significant variation in thickness of the capillary basement membrane at different sites within the same muscle. In one subject so studied, this variation was found regardless of the method of fixation or the method of measurement of capillary basement membrane thickness used. Variation was present in diabetics suffering from long-term complications of the disease as well as in diabetics free of such complications. A reevaluation of the biologic significance of basement membrane thickness measurements, as presently applied, is indicated in the light of the variability of base-line values.