Reduced regional cerebral blood flow in aged noninsulin-dependent diabetic patients with no history of cerebrovascular disease: Evaluation by N-lsopropyl-123I-p-iodoamphetamine with single-photon emission computed tomography

Regional cerebral blood flow was measured using N-isopropyl-¹²³I-iodoamphetamine with single-photon emission computed tomography (CT) in 16 aged patients with noninsulin-dependent diabetes mellitus (NIDDM, average age 72.8 years, average fasting plasma glucose 7.7 mmol/L), and 12 nondiabetic subjects (71.6 years, 5.3 mmol/L). None had any history of a cerebrovascular accident. Systolic blood pressure (SBP), total cholesterol, and triglyceride levels did not differ between groups. Areas of hypoperfusion were observed in 14 diabetic patients (12 patients had multiple lesions) and in 6 nondiabetic abetic subjects (3 had multiple lesions). Areas where radioactivity was ≥65% of the maximum count of the slice was defined as a region with normal cerebral blood flow (region of interest A, ROI-A), and areas where the count was ≥45% were defined as brain tissue regions other than ventricles (ROI-B). The average $\text{ROI-A}\text{B}$ ratio of 16 slices was used as a semiquantitative indicator of normal cerebral blood flow throughout the entire brain. Mean $\text{ROI-A}\text{B}$ ratio was 49.6 ± 1.7% in the diabetic group, significantly lower than the 57.9 ± 1.6% at the nondiabetic group (p < 0.005). The ratio was inversely correlated with SBP (r = −0.61, p < 0.05), total cholesterol (r = −0.51, p < 0.05), and atherogenic index (r = −0.64, p < 0.01), and was positively correlated with high-density lipoprotein (HDL) cholesterol (r = 0.51, p < 0.05) in the diabetic, but not the nondiabetic group. These observations suggest that the age-related reduction in cerebral blood flow may be accelerated by a combination of hyperglycemia plus other risk factors for atherosclerosis.