SALT SENSITIVITY IS NOT ASSOCIATED WITH HYPERINSULINEMIA IN A SAMPLE OF RURAL BLACK ZIMBABWEANS

Objectives. To investigate the relationship between salt sensitivity a nd hyperinsulinaemia in rural black African subjects. Design. An inter vention study where 27 subjects were divided into two groups; group 1 was initially salt loaded (300 mmol Na+/day) while group 2 was salt re stricted (25 mmol Na+/day), each for 4 days, after which a cross-over study was done. Setting. Chidamoyo, a rural area 383 km north of Harar e, Zimbabwe. Subjects. Twenty-seven rural volunteers (16 women, 11 men ). Outcome measures. Systolic and diastolic blood pressures, salt sens itivity, insulin and glucose levels, body mass index and mean arterial pressure. Results. Mean arterial pressure, which was 91 +/- 2 mmHg on a low-salt diet, increased significantly (P < 0.01) to 105 +/- 3 mmHg on a high-salt diet in the salt-sensitive subjects. In the same salt- sensitive subjects, the fasting insulin level was 8.4 +/- 0.8 mu U/ml on a low-salt and 6.1 +/- 1.0 mu U/ml on a high-salt diet. The differe nce was not statistically significant. Conclusions. Although salt pres ser sensitivity was demonstrated in the subjects, there was no accompa nying increase but rather a decrease in fasting insulin levels, sugges ting that in the short term, salt sensitivity and hyperinsulinaemia ar e not linked in raising blood pressure in this sample of rural Zimbabw ean subjects.