Lack of association between blood pressure and insulin in patients with insulinoma

To investigate the hypothesis that insulin affects the regulation of blood pressure, blood pressure and fasting insulin and glucose levels were measured in seven patients with insulinoma both before and after resection of the insulinoma. The diagnosis of all insulinoma cases was confirmed during surgery. Before surgery, systolic and diastolic blood pressures were 127 +/- 15 and 74 +/- 9 mmHg, respectively, and did not correlate with the fasting insulin levels. At least 3 weeks after the surgery, significant decreases in fasting insulin levels (from 568 +/- 571 to 74 +/- 43 pmol/l, P less than 0.005) and body weight (-9.8 +/- 7.1%, P less than 0.05) were observed along with a significant increase in fasting glucose levels (98.2 +/- 43.2%, P less than 0.001). However, both systolic (-4.7 +/- 9.9%) and diastolic (-0.2 +/- 6.3%) blood pressures remained unchanged. The changes in fasting insulin levels were not linearly correlated with those in systolic and diastolic blood pressures. Even after the changes in both body weight and fasting glucose levels were taken into consideration using partial correlations, the changes in fasting insulin levels did not correlate with those in systolic and diastolic blood pressures. It was concluded that blood pressure, both systolic and diastolic, was not at hypertensive levels in the patients with insulinoma and showed no decrease after resection of the insulinoma. Therefore, insulin may not affect the regulation of blood pressure in patients with insulinoma.