Insulin regulates arginine-stimulated insulin secretion in humans

Aims: Insulin potentiates glucose-stimulated insulin secretion. These effects are attenuated in beta cell-specific insulin receptor knockout mice and insulin resistant humans. This investigation examines whether short dura-tion insulin exposure regulates beta cell responsiveness to arginine, a non-glucose secretagogue, in healthy humans. Materials and methods: Arginine-stimulated insulin secretion was studied in 10 healthy humans. In each subject arginine was administered as a bolus followed by continuous infusion on two occasions one month apart, after sham/saline or hyperinsulinemic-isoglycemic clamp, respectively providing low and high insulin pre-exposure conditions. Arginine-stimulated insulin secretion was measured by C-peptide deconvolution, and by a selective immunogenic (DAKO) assay for direct measurement of endogenous but not exogenous insulin. Results: Pre-exposure to exogenous insulin augmented arginine-stimulated insulin secretion. The effect was seen acutely following arginine bolus (endogenous DAKO insulin incremental AUC(240-255min) 311.6 +/- 208.1 (post-insulin exposure) versus 120.6 +/- 42.2 mu U/ml.min (sham/saline) (t-test P = 0.021)), as well as in response to continuous arginine infusion (DAKO insulin incremental AUC(260-290min) 1095.3 +/- 592.1 (sham/saline) versus 564.8 +/- 207.1 mu U/ml.min (high insulin)(P = 0.009)). Findings were similar when beta cell response was assessed using C-peptide, insulin secretion rates by deconvolution, and the C-peptide to glucose ratio. Conclusions: We demonstrate a physiologic role of insulin in regulation of the beta cell secretory response to arginine. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

This study investigates the regulatory role of insulin in the beta cell response to arginine stimulation in healthy humans. The results demonstrate that pre-exposure to insulin enhances arginine-stimulated insulin secretion. This finding reveals the physiological role of insulin in regulating beta cell response to non-glucose secretagogues.