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Erschienen in:
01.04.2008 | Article
Near normalisation of blood glucose improves the potentiating effect of GLP-1 on glucose-induced insulin secretion in patients with type 2 diabetes
Erschienen in: Diabetologia | Ausgabe 4/2008
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Aims/hypothesis
The ability of glucagon-like peptide-1 (GLP-1) to enhance beta cell responsiveness to i.v. glucose is impaired in patients with type 2 diabetes mellitus compared with healthy individuals. We investigated whether 4 weeks of near normalisation of blood glucose (BG) improves the potentiation of glucose-stimulated insulin secretion by GLP-1.
Methods
Nine obese patients with type 2 diabetes and inadequate glycaemic control (HbA1c 8.0 ± 0.4%) were investigated before and after 4 weeks of near normalisation of BG using insulin treatment (mean diurnal blood glucose 6.4 ± 0.3 mmol/l, HbA1c 6.6 ± 0.3%). Nine matched healthy participants were also studied. Beta cell function was investigated before and after insulin treatment using stepwise glucose infusions and infusion of saline or GLP-1 (1.0 pmol kg−1 min−1), resulting in supraphysiological total GLP-1 concentrations of approximately 200 pmol/l. The responsiveness to glucose or glucose+GLP-1 was expressed as the slope of the linear regression line relating insulin secretion rate (ISR) and plasma glucose concentration (pmol kg−1 min−1 [mmol/l]−1).
Results
In the diabetic participants, the slopes during glucose+saline infusion did not differ before and after insulin treatment (0.33 ± 0.07 and 0.39 ± 0.04, respectively; p = NS). In contrast, near normalisation of blood glucose improved beta cell sensitivity to glucose during glucose+GLP-1 infusion (1.27 ± 0.2 before vs 1.73 ± 0.31 after; p < 0.01). In the healthy participants, the slopes during the glucose+saline and glucose+GLP-1 infusions were 1.01 ± 0.14 and 4.79 ± 0.53, respectively.
Conclusions/interpretation
A supraphysiological dose of GLP-1 enhances beta cell responses to glucose in patients with type 2 diabetes, and 4 weeks of near normalisation of blood glucose further improves this effect.
ClinicalTrials.gov ID no.: NCT00612625