| There are about 1.5 hundred million diabetic patients in the world at present according to WHO's report, and the number will be doubled up to 2025. China has more than 30 millions diabetic patients today, and the incidence of diabetes mellitus is rising due to inappropriate increase in calorie intake and decreased physical activity. Among diabetic patients, hypertension has a prevalence of 30%- 40% and diabetic patients with hypertension has a significantly higher rate of cerebrovascular disease. Detection of cerebrovascular reactivity can evaluate the cerebrovascular function. Cerebrovascular reactivity reflects the cerebrovascular reserve capacity. Recent researches had shown that impaired cerebrovascular reactivity was an important determinant in the risk of stroke. Diabetes mellitus and hypertension are all risk factors of cerebrovascular disease. No study has reported whether hypertension can aggravated the cerebrovascular reserve capacity damage among diabetic patients. Objective: The aim of the present work was to investigate the impact of hypertension on cerebrovascular reserve capacity among type 2 diabetic patients by evaluating hemodynamic status of the middle cerebral artery (MCA) and cerebrovascular reactivity. Methods: Thirty-six cases of type 2 diabetic patients without hypertension(DM group) , thirty-four cases of type 2 diabetic patients with essential hypertension(DM+EH group), thirty-three cases of essential hypertensive patients(EH group) and thirty-nine cases of healthy control subjects(CONTROL group) entered the study and were detected using transcranial color-coded deplux sonography(TCCD). Hypercapnia were produced by means of breath-holding test. The mean velocity (Vmca), peak systolic velocity(Vs), end diastolic velocity(Vd), pulsatility index(PI), resistance index(RI) of MCA and the diameter of MCA(Dmca) were measured at rest and after breath holding of 25s.The blood flow volume of MCA (BFVmca) were calculated with the formula: BFVmca (ml/ min) = (Dmca/ 2)2·π·Vmca·60. The cerebrovascular reactivity to hypercapnia was evaluated by calculating the increase percent of Vmca and BFVmca. Results: At rest, Vs was significantly higher in DM+EH group than those of CONTROL group(P<0.05). Vmca was significantly higher in DM+EH group than those of EH group(P<0.05) and CONTROL group(P<0.05). PI was significantly higher in DM+EH group than those of CONTROL group(P<0.05). RI was significantly higher in DM+EH group than those of DM group(P<0.01) and CONTROL group(P<0.01). Dmca was significantly thiner in DM+EH group than those of CONTROL group(P<0.01). Vd and Vmca had no significant difference compared between groups at rest. The increase percent of Vmca were 29.34±4.50% in DM group, 29.35±4.35% in EH group, 26.68±4.99% in DM+EH group, and 30.99±3.54% in CONTROL group respectively. It was significantly lower in DM+EH group than those of DM group(P<0.05), EH group(P<0.05) and CONTROL group(P<0.01). The increase percent of BFVmca were 35.32±5.08% in DM group, 35.36±6.16% in EH group, 31.78±7.11% in DM+EH group, and 37.26±4.17% in CONTROL group respectively. It was significantly lower in DM+EH group than those of DM group(P<0.05), EH group(P<0.05) and CONTROL group(P<0.01).The increase percent of Dmca were 2.29±1.09% in DM group, 2.27±0.95% in EH group, 1.97±1.05% in DM+EH group, and 2.36±0.46% in CONTROLgroup respectively. It was significantly lower in DM+EH group than those of CONTROL group.The abnormal rate of MCA spectrum was 27.78% in DM group, 27.27% in EH group, 47.06% in DM+EH group, and 25.64% in CONTROL group respectively. It was significantly lower in DM+EH group than those of CONTROL group(P<0.05)。The abnormal rate of MCA spectrum was 36.11% in DM group, 39.39% in EH group, 64.71% in DM+EH group, 33.33% in CONTROL group respectively. It was significantly higher in DM+EH group than the other groups(P<0.05). Conclusions: 1. The patients with both DM and EH had markedly increased Vs, Vmca, PI, RI and decreased Dmca at rest as well as impaired cerebrovascular reactivity. Hyper...
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