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JAMES C. BEARD, W. KENNETH WARD, BRAD J. WALLUM, DANIEL PORTE, Relationship of Islet Function to Insulin Action in Human Obesity, The Journal of Clinical Endocrinology & Metabolism, Volume 65, Issue 1, 1 July 1987, Pages 59–64, https://doi.org/10.1210/jcem-65-1-59
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To analyze B-cell mechanisms in obesity, we measured the relationship (slope of potentiation) between glucose levels and acute insulin responses (AIR) to isoproterenol or arginine in nondiabetic subjects ranging from lean to markedly obese. Obese men (n = 9) had higher AIRs to isoproterenql than lean men (n = 11) at basal glucose levels [52 ± 9 (sem) vs. 32 ± 5 μU/mL; P < 0.05], and the difference increased as the ambient glucose level was raised (at 230 mg/dL;, 263 ± 22 vs. 140 ±21 μU/mL; P < 0.0008). The individuals' slopes of glucose potentiation of AIR to isoproterenol were positively correlated with their excess weight (r = 0.72; P < 0.001). Similar results were found when arginine was used as the secretagogue in other men and in women; the slope of potentiation was positively correlated with excess weight in both men and women (both P < 0.005), although the effect of excess weight on slope was 51% greater among men (P < 0.03).
An independent measurement of insulin sensitivity (the Bergman SI) was made in the women. The potentiation slope was inversely correlated with SI (P < 0.0001), indicating that the effect of obesity on insulin secretion is correlated with insulin resistance. These results characterize one mechanism contributing to the hyperinsulinemia of obesity and highlight the importance of considering the prevailing insulin sensitivity when assessing islet function.
