Plasma and tissue fibronectin in diabetes.

Plasma fibronectin was determined by laser immunonephelometry in controls (90 women, 66 men) and 167 diabetic patients between 10 and 60 years of age, 72 insulin-dependent males, 45 insulin-dependent females, 29 noninsulin-dependent males and 21 non-insulin-dependent females. The distribution and intensity of immunofluorescent tissue fibronectin were also studied in the patients using skin biopsies. The diabetic patients had a significantly lower plasma fibronectin level than the controls of the same age-groups and did not exhibit the strong age-dependent increase found for controls. This was true for both females and males, and especially pronounced for the insulin-dependent male patients below 45 years. The duration (less or more than 10 years), and control of diabetes (judged by the glycosylated hemoglobin A1C levels, presence or absence of retinopathy), had a lesser influence on plasma fibronectin levels, although the duration of the disease tended to increase plasma fibronectin levels. Tissue fibronectin appeared to increase as estimated by the intensity and distribution of immunofluorescence in the papillary dermis, and in vascular and dermo-epidermal basement membranes, suggesting an inverse variation of tissue and plasma fibronectin in diabetes.