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J Clin Endocrinol Metab. 2009 Feb;94(2):603-8. doi: 10.1210/jc.2008-1731. Epub 2008 Dec 2.

KATP channel closure ameliorates the impaired insulinotropic effect of glucose-dependent insulinotropic polypeptide in patients with type 2 diabetes.

Author information

1
Department of Internal Medicine F, Gentofte Hospital, University of Copenhagen, Niels Andersens Vej 65, Hellerup DK-2900, Denmark. Kasper@dadlnet.dk

Abstract

OBJECTIVE:

The reduced incretin effect in subjects with type 2 diabetes is accompanied by a severely impaired insulinotropic effect of the incretin hormone glucose-dependent insulinotropic polypeptide (GIP). The K(ATP) channels of the beta-cell appear to be essential for the function of GIP in mice, and mutations in the gene encoding these channels have been linked to the development of type 2 diabetes. With this study we therefore aimed at clarifying the role of K(ATP) channel malfunction in the impaired function of GIP.

RESEARCH DESIGN AND METHODS:

We examined 12 subjects with type 2 diabetes using a 2-h (15 mM) hyperglycemic clamp on 4 separate days with concomitant infusion of one of the following: GIP; GIP + 10 mg sulfonylurea (SU, glipizide) taken orally 1 h before the clamp; saline + 10 mg SU; or saline alone. Blood was sampled to measure plasma concentrations of glucose, intact GIP, insulin, C-peptide, and glucagon.

RESULTS:

Compared to the results of GIP alone, SU alone, or those results added together, coadministration of GIP and SU resulted in a more-than-additive increase in the peripheral insulin (P = 0.002) and C-peptide (P = 0.028) responses and furthermore, a more-than-additive increase in total (P = 0.01), early (P = 0.02), and late-phase (P = 0.02) insulin secretion.

CONCLUSION:

We have demonstrated that inhibiting the K(ATP) channels of the diabetic beta-cell acutely using SU significantly increases both the peripheral insulin response to GIP and GIP-induced insulin secretion, indicating an ameliorated insulinotropic effect of GIP.

PMID:
19050053
DOI:
10.1210/jc.2008-1731
[Indexed for MEDLINE]

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