Ba. Swinburn et al., IN-VIVO BETA-CELL FUNCTION AT THE TRANSITION TO EARLY NON-INSULIN-DEPENDENT DIABETES-MELLITUS, Metabolism, clinical and experimental, 44(6), 1995, pp. 757-764
Impaired insulin secretion occurs at some stage in the development of
non-insulin dependent diabetes mellitus (NIDDM), possibly during impai
red glucose tolerance (IGT) or early NIDDM. To assess insulin secretio
n at these critical stages, we measured the first-phase insulin respon
se (to glucose and arginine), maximal secretory capacity, and glucose
potentiation slope for insulin secretion in Pima Indians with normal g
lucose tolerance (n = 20), IGT (n = 9), and mild (fasting glucose < 7.
8 mmol/L) NIDDM (n = 7). We also measured oral glucose tolerance and i
nsulin action. Subjects with IGT were more insulin-resistant (P < .05)
than normals. A wide range of insulin secretion was noted, although a
s a group, no significant impairment was detected. Subjects with mild
NIDDM were similarly insulin-resistant, but they also had impaired ins
ulin secretion. The first-phase response to glucose was markedly reduc
ed in absolute terms (P < .001), but all secretion indices were impair
ed relative to the degree of insulin resistance (P = .05 to P < .0001)
. These results suggest that in Pima Indians, impairment of insulin se
cretion, especially the first-phase response to glucose, is associated
with mild NIDDM. Insulin secretion in IGT is variable and, overall, s
eems intact, although a subtle defect in the first-phase insulin respo
nse to glucose could not be ruled out in this study. Glucose sensing f
or first-phase secretion may be one of the early secretory defects in
the progression of glucose intolerance and seems to be critical at the
transition from IGT to early NIDDM. Copyright (C) 1995 by W.B. Saunde
rs Company