Diabetic macroangiopathy. Quantitative histopathological studies of the extramural coronary arteries from type 2 (non-insulin-dependent) diabetic patients.

A morphometric study was performed on histological sections of the extramural coronary arteries from 10 Type 2 (non-insulin-dependent) diabetic patients and 10 non-diabetic subjects, matched for age and sex. Standardised samples were taken from the two coronary arteries and the fractional contents of Periodic Acid-Schiff-positive material, acid mucopolysaccharides and connective tissue was determined in the arterial tunica media from the two groups using a point-counting technique. The thickness of tunica intima and tunica media was obtained by micrometric measurements. There was no difference in the thickness of tunica intima with and without atherosclerotic plaque between the vessels from diabetic and nondiabetic hearts. However, the thickness of tunica media was significantly reduced in arteries from the diabetic patients (2p less than 0.01). In tunica media of the diabetic patients there was a significant increase (50%) in the amount of Periodic Acid-Schiff-positive material (2p less than 0.01), whereas the content of acid mucopolysaccharides (alcian-blue positive) was significantly reduced (2p less than 0.02). These changes in tunica media were similar in areas below and outside the intimal atherosclerotic plaques. The content of connective tissue was found to be significantly increased in the arteries from the diabetic patients, but only in areas outside atherosclerotic plaques (2p less than 0.025). There was no correlation between the observed changes in tunica media and the known duration of diabetes. The results obtained in the present study may be ascribed to the presence of a non-atherosclerotic diabetic macroangiopathy.