Relationship between insulin response to oral glucose load and creatinine clearance

In order to investigate the relationship between insulin response to oral glucose load and renal function, a 100-gm. oral glucose tolerance test was performed in twenty-two patients with chronic glomerulonephritis, whose creatinine clearances ranged form 5 to 96 ml. per minute. Glucose areas during oral glucose load were little affected by the creatinine clearance in this study. Insulin area during oral glucose load increased in proportion to the decrease in creatinine clearance. The ratio of insulin area to glucose area correlated closely with creatinine clearance and a linear relationship was obtained (y = 1.46 - 0.01x, r = -0.82, p less than 0.001). There were also significant correlations with serum creatinine, blood urea nitrogen, and PSP (r = 0.6, 0.63, and -0.62, respectively). These results show that the impaired renal function has a significant influence on the plasma insulin levels, and it seems likely that such influence becomes manifest below approximately 60 ml. per minute of creatinine clearance.