Impaired vascular reactivity during the first two years of diabetes mellitus after initial restoration.

Vascular reactivity was studied prospectively in 36 consecutive children (15 males, 21 females) below 15 years from the county of Uppsala with newly acquired type I diabetes mellitus (IDDM). Skin postocclusive hyperaemia was recorded with a transcutaneous oxygen electrode at 37 degrees C on admission before receiving insulin treatment and 1, 6, 12 and 24 months after diagnosis. Fifty-eight healthy children (25 males, 33 females), served as a reference group. The relations between vascular reactivity and age, sex and a number of biochemical variables that are often disturbed in IDDM were analyzed. On admission, the vascular reactivity was significantly lower in diabetic children than in controls (p less than 0.001). This reduction was normalized during the first month of treatment. After two years of diabetes, the vascular reactivity was again significantly lower in diabetic children than in the control group (p less than 0.001). There was no significant correlation between the vascular reactivity, the lag phase or baseline variables and any of the factors mentioned above at any time of investigation, except that serum magnesium was significantly correlated with vascular reactivity after six months of IDDM. It is suggested that the mechanism underlying an impairment of vascular reactivity on admission (reversible) is different from that of the late reduction, which might be a very early manifestation of the later structural diabetic microangiopathy.