The aim of the study was to test the hypothesis that cerebrovascular reserve capacity
and cerebrovascular reactivity are impaired in patients suffering from non insulin-dependent
diabetes mellitus. We also intended to investigate factors which may influence resting
cerebral blood flow velocity and cerebrovascular reserve capacity. A total of 28 patients
suffering from type II diabetes mellitus and 20 healthy control subjects were studied.
Based on diabetes duration patients were divided into two groups: subjects with >
10 years and those with < or = 10 years disease duration. Middle cerebral artery mean
blood flow velocities were measured at rest and after intravenous administration of
1g acetazolamide. Cerebrovascular reactivity and reserve capacity were calculated.
Blood glucose, insulin, glycosylated hemoglobin, hemostatic factors (fibrinogen, alpha-2
macroglobulin and von Willebrand factor antigen) were determined. Cerebrovascular
reactivity and reserve capacity values were compared between the two diabetic subgroups
and controls. Correlations between laboratory parameters and cerebrovascular reserve
were investigated by linear regression analysis. Resting cerebral blood flow velocity
was similar in controls and in the two diabetic subgroups. Cerebrovascular reactivity
was elevated for a shorter time in patients with > 10 years disease duration than
in controls and short-term diabetic patients. Cerebrovascular reserve capacity was
lower in the long-term diabetes group (means +/- SD: 39.6 +/- 20.7%) than in patients
with < or = 10 years disease duration (63.3 +/- 17.4%, p < 0.02 after Bonferroni correction).
Cerebrovascular reserve capacity was inversely related to the duration of the disease
(R = 0.53, p < 0.003). None of the determined laboratory factors had any relation
with resting cerebral blood flow and cerebrovascular reserve capacity. The vasodilatory
ability of cerebral arterioles is diminished in long-standing type II diabetes mellitus.