title: Secretion of glucagon-like peptide-1 in patients with type 2 diabetes mellitus: systematic review and meta-analyses of clinical studies.
abstract: OBJECTIVE
  We carried out a systematic review of clinical studies investigating glucagon-like peptide-1 (GLP-1) secretion in patients with type 2 diabetes and non-diabetic controls and performed meta-analyses of plasma total GLP-1 concentrations during an OGTT and/or meal test.
  
  
  METHODS
  Random effects models for the primary meta-analysis and random effects meta-regression, subgroup and regression analyses were applied.
  
  
  RESULTS
  Random effects meta-analysis of GLP-1 responses in 22 trials during 29 different stimulation tests showed that patients with type 2 diabetes (n = 275) and controls without type 2 diabetes (n = 279) exhibited similar responses of total GLP-1 (p = NS) as evaluated from peak plasma concentrations (weighted mean difference [95% CI] 1.09 pmol/l [-2.50, 4.67]), total AUC (tAUC) (159 pmol/l × min [-270, 589]), time-corrected tAUC (tAUC min⁻¹) (0.99 pmol/l [-1.28, 3.27]), incremental AUC (iAUC) (-122 pmol/l × min [-410, 165]) and time-corrected iAUC (iAUC min⁻¹) (-0.49 pmol/l [-2.16, 1.17]). Fixed effects meta-analysis revealed higher peak plasma GLP-1 concentrations in patients with type 2 diabetes. Subgroup analysis showed increased responses after a liquid mixed meal test (peak, tAUC and tAUC min⁻¹) and after a 50 g OGTT (AUC and tAUC min⁻¹), and reduced responses after a solid mixed meal test (tAUC min⁻¹) among patients with type 2 diabetes. Meta-regression analyses showed that HbA1c and fasting plasma glucose predicted the outcomes iAUC and iAUC min⁻¹, respectively.
  
  
  CONCLUSIONS
  The present analysis suggests that patients with type 2 diabetes, in general, do not exhibit reduced GLP-1 secretion in response to an OGTT or meal test, and that deteriorating glycaemic control may be associated with reduced GLP-1 secretion.
authors: Diabetes Research Division, Department of Internal Medicine, Gentofte Hospital, University of Copenhagen, Niels Andersens Vej 65, DK-2900 Hellerup, Denmark.
authors: S
authors: S
authors: Calanna
authors: M
authors: M
authors: Christensen
authors: J J
authors: JJ
authors: Holst
authors: B
authors: B
authors: Laferrère
authors: L L
authors: LL
authors: Gluud
authors: T
authors: T
authors: Vilsbøll
authors: F K
authors: FK
authors: Knop
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000378:metabolism* / Q000503:physiopathology; D015536:Down-Regulation; D019858:Enteroendocrine Cells / Q000378:metabolism; D052216:Glucagon-Like Peptide 1 / Q000097:blood / Q000378:metabolism*; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D006943:Hyperglycemia / Q000209:etiology; D007413:Intestinal Mucosa / Q000378:metabolism*; D019518:Postprandial Period; D012720:Severity of Illness Index
chemical_list: D052216:Glucagon-Like Peptide 1; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human
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