Potentiated beta-cell response to non-glucose stimuli in insulin-resistant C57BL/6J mice

Insulin secretion in response to acetylcholine receptor activation by carbachol in insulin resistance induced by 12 weeks of high-fat diet in C57BL/6J mice is exaggerated. To study whether this persists after a longer period of time and also involves other non-glucose stimuli, we fed C57BL/6J mice a high-fat diet for 24 weeks. Both hyperinsulinemia (341 +/- 33 vs. 148 +/- 15 pmol/l) and slight hyperglycemia (7.8 +/- 0.2 vs. 6.1 +/- 0.1 mmol/l) were evident at this time point. The insulinotropic response to high dose carbachol (0.53 micromol/kg; 3403 +/- 377 vs. 1595 +/- 429 pmol/l), to the glucose analogue, 2-deoxyglucose (6 mmol/kg; 2014 +/- 315 vs. 1167 +/- 200 pmol/l), to cholecystokinin-8 (15.9 nmol/kg; 499 +/- 93 vs. 119 +/- 40 pmol/l) and to glucagon-like peptide-1 (32 nmol/kg; 307 +/- 86 vs. 71 +/- 9 pmol/l), were all exaggerated in mice given high-fat diet. In contrast, the insulin response to glucose was impaired. This shows that insulin resistance is accompanied by a general islet supersensitivity to non-glucose stimuli, which persists over a long period of time.