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Abstract The incretin hormones glucagon‐like peptide‐1 (GLP‐1) and glucose‐dependent insulinotropic polypeptide (GIP), are thought to be the main drivers of insulin secretion in individuals with sulfonylurea (SU)‐treated KCNJ11 permanent neonatal diabetes. The aim of this study was to assess for the first time the incretin hormone response to carbohydrate and protein/fat in adults with sulfonylurea‐treated KCNJ11 permanent neonatal diabetes compared with that of controls without diabetes. Participants were given a breakfast high in carbohydrate and an isocaloric breakfast high in protein/fat on two different mornings. Incremental area under the curve and total area under the curve (0‐240 minutes) for total GLP‐1 and GIP were compared between groups, using non‐parametric statistical methods. Post‐meal GLP‐1 and GIP secretion were similar in cases and controls, suggesting this process is adenosine triphosphate‐sensitive potassium channel‐independent. Future research will investigate whether treatments targeting the incretin pathway are effective in individuals with KCNJ11 permanent neonatal diabetes who do not have good glycemic control on sulfonylurea alone.

Objective Insulin secretion in sulfonylurea-treated KCNJ11 permanent neonatal diabetes mellitus (PNDM) is thought to be mediated predominantly through amplifying non-KATP-channel pathways such as incretins. Affected individuals report symptoms of postprandial hypoglycemia after eating protein/fat-rich foods. We aimed to assess the physiological response to carbohydrate and protein/fat in people with sulfonylurea-treated KCNJ11 PNDM.Research design and methods 5 adults with sulfonylurea-treated KCNJ11 PNDM and five age, sex and body mass index-matched controls without diabetes had a high-carbohydrate and high-protein/fat meal on two separate mornings. Insulin(i) and glucose(g) were measured at baseline then regularly over 4 hours after the meal. Total area under the curve (tAUC) for insulin and glucose was calculated over 4 hours and compared between meals in controls and KCNJ11 cases.Results In controls, glucose values after carbohydrate and protein/fat were similar (median glucose tAUC0-4h21.4 vs 19.7 mmol/L, p=0.08). In KCNJ11 cases glucose levels were higher after carbohydrate than after protein/fat (median glucose tAUC0-4h58.1 vs 31.3 mmol/L, p=0.04). These different glycemic responses reflected different patterns of insulin secretion: in controls, insulin secretion was greatly increased after carbohydrate versus protein/fat (median insulin tAUC0-4h727 vs 335 pmol/L, p=0.04), but in KCNJ11 cases insulin secretion was similar after carbohydrate and protein/fat (median insulin tAUC0-4h327 vs 378 pmol/L, p=0.50).Conclusions Individuals with sulfonylurea-treated KCNJ11 PNDM produce similar levels of insulin in response to both carbohydrate and protein/fat meals despite carbohydrate resulting in much higher glucose levels and protein/fat resulting in relatively low glucose levels. This suggests in an inability to modulate insulin secretion in response to glucose levels, consistent with a dependence on non-KATP pathways for insulin secretion.Trial registration number NCT02921906.