Increased minimal vascular resistance and arteriolar hyalinosis in skin on the leg in insulin-dependent diabetic patients

Abstract

Minimal vascular resistance (MVR) was determined in a paralysed cutaneous vascular bed at the dorsum of the foot in diabetic patients. Twelve long-term insulin-dependent diabetic (IDDM) patients with and nine short-term IDDM patients without nephropathy and retinopathy and eight control subjects were investigated. The vascular bed was paralysed by local injection of histamine. Skin perfusion pressure was varied by applying graded external counter pressure over the investigated area. Skin blood flow was measured by the local ^99mTc wash-out technique before, during and after three to five step-wise increases of external counter pressure. The MVR was calculated from the reciprocal of the slope of the relationship between blood flow and applied pressure. The MVR was significantly increased in diabetic patients with (mean: 9.3 mmHg ml^-1 ·100 g·min) and without nephropathy and retinopathy (8.5 mmHg ml^-1·100 g·min) compared with non-diabetic subjects (5.2 mmHg ml^-1·100 g·min) (p<0.001 and p<0.005, respectively). Diabetic microangiopathy (increased hyalinusis of the basement membranes in the terminal arterioles) was found in skin biopsies in nine of the 12 long-term IDDM patients and in four of the nine short-term IDDM patients, but not in the control subjects. Multiple regression analysis demonstrated a highly significant direct association between MVR and degree of diabetic microangiopathy in the same skin area (p<0.0002). A less significant direct association between MVR and arm diastolic blood pressure (p<0.05) and blood glucose concentration (p<0.05) was also found. Our results indicate, that terminal arteriolar hyalinosis is the main determinant of the increased minimal vascular resistance in skin in short- and long-term IDDM patients.

Key words:

• cutaneous blood flow
• diabetic microangiopathy
• microcirculation
• type 1 diabetes
• vascular resistance