title: Higher insulin and glucagon-like peptide-1 (GLP-1) levels in healthy, young South Asians as compared to Caucasians during an oral glucose tolerance test.
abstract: OBJECTIVE
  Higher insulin levels during an oral glucose test (OGTT) have been shown in South Asians. We aimed to investigate if this increased insulin response causes reactive hypoglycemia later on, and if an increased glucagon-like-peptide-1 (GLP-1) response, which could contribute to the hyperinsulinemia, is present in this ethnic group.
  
  
  METHODS
  A prolonged, 6-h, 75-g OGTT was performed in healthy, young Caucasian (n=10) and South Asian (n=8) men. The glucose, insulin and GLP-1 response was measured and indices of insulin sensitivity and beta-cell activity were calculated.
  
  
  RESULTS
  Age (Caucasians (CAU) 21.5±0.7 years vs South Asians (SA) 21.4±0.7 years (mean±SEM)) and body mass index (CAU 22.7±0.7 kg/m(2) vs SA 22.1±0.8 kg/m(2)) were comparable between the two groups. South Asian men were more insulin resistant, as indicated by a comparable glucose but significantly higher insulin response, and a significantly lower Matsuda index (CAU 8.7(8.6) vs SA 3.2(19.2), median(IQR)). South Asians showed a higher GLP-1 response, as reflected by a higher area under the curve for GLP-1 (CAU 851±99.8 mmol/l vs SA 1235±155.0 mmol/L). During the whole 6-h period, no reactive hypoglycemia was observed.
  
  
  CONCLUSIONS
  Healthy, young South Asian men have higher insulin levels during an OGTT as compared to Caucasians. This does not, however, lead to reactive hypoglycemia. The hyperinsulinemia is accompanied by increased levels of GLP-1. Whether this is an adaptive response to facilitate hyperinsulinemia to overcome insulin resistance or reflects a GLP-1 resistant state has yet to be elucidated.
authors.affiliation: Department of General Internal Medicine and Endocrinology & Metabolism, Leiden University Medical Center, Leiden, The Netherlands. Electronic address: m.a.sleddering@lumc.nl.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Sleddering
authors.affiliation: Department of General Internal Medicine and Endocrinology & Metabolism, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Leontine E H
authors.initials: LE
authors.lastname: Bakker
authors.affiliation: Department of General Internal Medicine and Endocrinology & Metabolism, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Laura G M
authors.initials: LG
authors.lastname: Janssen
authors.affiliation: Department of General Internal Medicine and Endocrinology & Metabolism, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: A Edo
authors.initials: AE
authors.lastname: Meinders
authors.affiliation: Department of General Internal Medicine and Endocrinology & Metabolism, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Ingrid M
authors.initials: IM
authors.lastname: Jazet
mesh_terms: D000328:Adult; D019540:Area Under Curve; D044466:Asian People; D001786:Blood Glucose / Q000378:metabolism; D052216:Glucagon-Like Peptide 1 / Q000097:blood*; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D008297:Male; D012016:Reference Values; D013532:Suriname; D044465:White People
chemical_list: D001786:Blood Glucose; D007328:Insulin; D052216:Glucagon-Like Peptide 1
keywords: AUC; BMI; CAU; Caucasian; DI(o); DPP-IV; Dipeptidyl peptidase IV; GLP-1; IGI; IQR; Insulin resistance; Insulin sensitivity; OGTT; SA; SEM; South Asian; T2DM; area under the curve; body mass index; glucagon-like-peptide-1; insulinogenic index; interquartile range; oral disposition index; oral glucose tolerance test; standard error of the mean; type 2 diabetes mellitus.