Muscle capillary basement membrane width is a sensitive marker for the presence of
diabetic microangiopathy. Studies have indicated that genetic factors and alterations in
glucose metabolism influence muscle capillary basement membrane width. To define the role of these factors we have measured muscle capillary basement membrane thickness in controls,
insulin dependent diabetics, and individuals with diabetes secondary to the ingestion of
Vacor, a rat
poison, which results in
hyperglycemia.
Hemoglobin A1 concentrations were increased in both diabetic groups, but
hemoglobin A1 levels and the duration of diabetes were similar in the two diabetic groups. The muscle capillary basement membrane width was increased to a similar extent in the
insulin-dependent diabetics (control, 1,781 +/- 46 vs. IDD, 2,287 +/- 144 A, P less than 0.001) and in the
Vacor diabetic group (2,320 +/- 149 A, P less than 0.001). In the
insulin-dependent diabetic group, 63% of the patients had a muscle capillary basement membrane width greater than two standard deviations above the mean of the controls, while in the
Vacor diabetic group this figure was 56%. Despite the relatively short duration of diabetes (6.2 +/- 0.3 yr), 44% of the
Vacor diabetic patients had retinopathy and 28% had
proteinuria. The present study provides strong evidence that even in the absence of genetic
diabetes mellitus,
hyperglycemia or some other abnormality related to
insulin lack can cause microvascular changes.