[Prevalence of hypertension in a black African diabetic population]

It has been established that hypertension prevalence rate was higher in American Blacks than Whites or Mexicans. And hypertension is more frequent in diabetics. The prevalence of hypertension among diabetic African Blacks is not well documented.

A total of 550 diabetic patients attending to Central Hospital of Yaounde (Cameroon) were followed between 1990 and 1994. The 1993 WHO criteria were used to define hypertension (systolic blood pressure (SBP) > or = 140 or diastolic blood pressure (DBP) > or = 90 mmHg. We also have considered as hypertensive patients being treated with an antihypertensive medication before inclusion. All quantitative data are given as means +/- SD.

For the whole study population characteristics were: age (at inclusion): 54.2 +/- 12.8 yrs: sex distribution: 341 men for 209 women (sex ratio: 1.63:1); known duration of diabetes: 5.7 +/- 5.6 yrs; Body Mass Index (BMI): 24.4 +/- 4.8 kg/m2. They are dividing into 136 IDDM, 405 NIDDM and 9 other types. In normotensive patients, blood pressure levels were: SBP 117 +/- 11 and DBP 75 +/- 8 mmHg, while in hypertensive: SBP 156 +/- 23 and DBP 95 +/- 13 mmHg. The difference between normo and hypertensive diabetics was significant (p > or = 0.001). Characteristics of hypertensive group were: age: 57 +/- 11.2 yrs, sex repartition 229 men for 136 women (sex ratio: 1.68:1), BMI: 24.9 +/- 4.8 kg/m2, diabetes classification: 63 IDDM, 297 NIDDM and 5 other types. According to recent WHO criteria (140/90) 365 subjects/550 were found to have high blood pressure, giving an overall prevalence of hypertension of 66.4% in the study population. Using former WHO definition (160/95) the prevalence was 42.2%. There was no statistical difference for prevalence between male (67.2%) and female (65.1%). But the difference was strongly significant (p < 0.001) between IDDM (46.3%) and NIDDM (73.3%).

Hypertension prevalence studies in Africa have shown varying results (2.5-30%), with higher rates in urban than rural population. In African studies hypertension prevalence rates in diabetes were reported in the range 13-44%. The result of the present study is very near the high limit of known data in Africa.

Such a prevalence rate of 66.4% in this Cameroonian diabetic population appears to be high, particularly in patients with NIDDM. These considerations bring to light the question of sensitiveness of African Blacks to hypertension when exposed to high blood pressure risk factors such as inadequate food and diabetes.