Diabetes Care, Vol 18, Issue 4 568-571, Copyright © 1995 by American Diabetes Association
Alterations in the patterns of insulin secretion before and after diagnosis of IDDM
NM O'Meara, J Sturis, KC Herold, DM Ostrega and KS Polonsky
Department of Medicine, University of Chicago, Pritzker School of Medicine, IL 60637, USA.
OBJECTIVE--To study the natural history of beta-cell dysfunction in an
individual who developed insulin-dependent diabetes mellitus (IDDM) over a
13-month period while under observation. RESEARCH DESIGN AND
METHODS--Insulin secretion rates (ISR) in response to intravenous glucose
and mixed meals were estimated by deconvolution of C-peptide levels.
RESULTS--When fasting glucose and glycosylated hemoglobin concentrations
were still within the normal range, insulin secretory responses to
intravenous glucose infusion were reduced, but 80- to 100-min secretory
oscillations could still be detected. Sequential glucose infusion studies
over a 3-month period demonstrated a progressive reduction in insulin
secretion. The tight temporal coupling between ultradian oscillations in
ISR and glucose observed in nondiabetic subjects was lost. In response to
mixed meals, the oscillatory pattern of secretion was preserved, but the
magnitude of the secretory responses was reduced. CONCLUSIONS--Our results
indicate that despite the lower absolute secretory rates, ultradian ISR
oscillations persist in the period before and immediately after the onset
of IDDM in this subject, but they are less tightly coupled to glucose than
in nondiabetic subjects.