Diabetes Care, Vol 21, Issue 5 810-816, Copyright © 1998 by American Diabetes Association
Changes in amylin and amylin-like peptide concentrations and beta-cell function in response to sulfonylurea or insulin therapy in NIDDM
J Rachman, MJ Payne, JC Levy, BA Barrow, RR Holman and RC Turner
Nuffield Department of Clinical Medicine, University of Oxford, U.K.
OBJECTIVE: Amylin, a secretory peptide of beta-cells, is the constituent
peptide of islet amyloid, which is characteristic of NIDDM, and changes in
amylin secretion in response to therapies may influence the rate of
production of islet amyloid. The primary objective of this study was to
determine whether therapy with sulfonylurea or basal insulin in NIDDM would
alter amylin secretion in a way that might affect the formation of islet
amyloid. RESEARCH DESIGN AND METHODS: In a randomized crossover design,
eight subjects with NIDDM underwent three 8-week periods of therapy with
diet alone, sulfonylurea, or exogenous basal insulin, with evaluation of
amylin, amylin-like peptide (ALP), and glucose and C-peptide
concentrations, both during fasting and after a standard breakfast. Changes
in beta-cell function (% beta) were assessed, in the basal state by
homeostasis model assessment (HOMA) and in the stimulated state by
hyperglycemic clamps. Seven nondiabetic control subjects each underwent a
meal profile and hyperglycemic clamp. RESULTS: Both sulfonylurea and
insulin therapy reduced basal glucose concentrations compared with diet
alone, but neither reduced the increased postprandial glucose increments.
Both sulfonylurea and insulin therapy increased basal % beta, assessed by
HOMA, but only sulfonylurea increased the second-phase C-peptide responses
to the hyperglycemic clamp. Sulfonylurea increased time-averaged mean
postprandial amylin and ALP concentrations compared with diet alone
(geometric mean [1-SD range] for amylin, 4.9 [2.0-11.8] vs. 3.0 [1.4-6.2]
pmol/l, P = 0.003; for ALP, 16.4 [8.5-31.7] vs. 10.1 [4.9-20.8] pmol/l, P =
0.001). Insulin therapy reduced basal ALP concentrations compared with diet
alone (2.9 [1.5-5.6] vs. 6.0 [2.6-13.6] pmol/l, P = 0.03), but had no
effect on postprandial concentrations of amylin (3.0 [1.3-6.5] pmol/l) or
ALP (10.0 [5.5-18.1] pmol/l). CONCLUSIONS: By increasing postprandial
concentrations of the constituent peptides of islet amyloid, sulfonylurea
therapy might increase the rate of deposition of islet amyloid and thereby
accelerate the decline of % beta in NIDDM, compared with diet therapy
alone.