Elevated Insulin Clearance Contributes to the Reduced Peripheral Insulin Concentration Observed in Obese Young Asian with Type 2 Diabetes

Abstract

Introduction: The importance of insulin clearance (CLins) on insulin dynamics and the role exerted in controlling glucose in type 2 subjects has recently been appreciated. Moreover, evidence in mice showed that CLins is reduced by incretin hormones at physiological levels. Aim: To evaluate in 29 young (19±1 years) multi-ethnic Asian type 2 subjects (T2D) the contribution of CLins to insulin dynamics and if an association exists with GLP-1. Methods: T2D (15F/14M; BMI=30.2±0.9 kg/m2; HbA1c=8.8±0.4% [73±4.4 mmol/mol]; mean duration of disease 2.5 years) had fasting glucose Gb=192±14 mg/mL and insulin Ib=19±3 µU/mL. They were compared to 17 (8F/9M) age-matched nondiabetic overweight (BMI=27.8±1.0, p=0.1) control subjects (CT, Gb=82±1, p<0.0001; Ib=12±2, p=0.09). All underwent a 75g 2h OGTT with measurements of glucose, insulin, C-peptide and GLP-1. Insulin secretion (ISR) was assessed by deconvolution from peripheral C-peptide; CLins) by ISR/AUCinsulin; beta cell function (BCF) by AUCC-peptide/AUCglucose; insulin sensitivity by OGIS model. GLP-1 effect on BCF (GLPE) was empirically calculated as BCF/AUCGLP-1. Results: T2D were insulin resistant (OGIS=277±16 mL/min m2 vs. 424±14) and had low BCF (82±11 pmolC-peptide/mmolglucose vs. 123±10), both p<0.0001. Lower total AUCinsulin was observed in T2D (4.7±0.7 U/L 2h vs. 11.0±1.4, p<0.0001), with higher CLins (2.06±0.19 L/min) than in CT (1.46±0.10, p=0.023). CLins directly correlated with OGIS in CT (R=0.55, p=0.02), but not in T2D (p=0.98). Despite no difference was observed in AUCGLP-1 (1.6±0.1 nmol/L 2h vs. 1.7±0.1 in CT, p=0.63), which did not correlate with CLins (p>0.2), GLPE was lower in T2D (6.2±0.9 vs. 23.4±2.3, p<0.0001). Conclusion: Reduced peripheral insulin availability in obese young Asian T2D is due not only to a markedly impaired beta cell function and reduced GLP-1 effect, but also to an increased insulin clearance, which however shows no association to GLP-1 response. Disclosure G. Pacini: None. A. Tura: None. C. Hor: None. S. Lim: None. F. Tan: None. C. Tong: None. J.Y.H. Hong: None. F. Md Zain: None. J.J. Holst: Advisory Panel; Self; Novo Nordisk A/S. Board Member; Self; Zealand Pharma A/S. Speaker's Bureau; Self; Merck Sharp & Dohme Corp., AstraZeneca. Research Support; Self; Danish Diabetes Academy, Novo Nordisk Foundation. Other Relationship; Self; Antag Therapeutics. Other Relationship; Spouse/Partner; Antag Therapeutics. W. Mohamud: None. T. Yeow: None.