Diabetes, Vol 39, Issue 5 549-556, Copyright © 1990 by American Diabetes Association
Nonprogression of subclinical beta-cell dysfunction among first-degree relatives of IDDM patients. 5-yr follow-up of the Seattle Family Study
DK McCulloch, LJ Klaff, SE Kahn, SL Schoenfeld, CJ Greenbaum, RS Mauseth, EA Benson, GT Nepom, L Shewey and JP Palmer
Veterans Administration Medical Center, Seattle, WA 98108.
It is unknown among first-degree relatives of individuals with
insulin-dependent diabetes mellitus (IDDM) whether the disease process
occurs in relatively few but always progresses to clinical IDDM or whether
subclinical disease is more common but remains nonprogressive in many
cases. Islet cell antibodies (ICAs) were found in 21 of 724 (2.9%)
first-degree relatives during screening in the greater Seattle area between
1983 and 1988. Measures of beta-cell function (glucose disappearance rate
[Kg], fasting insulin, acute insulin response to intravenous arginine
[AIRarg], acute insulin response to intravenous glucose [AIRgluc], slope of
glucose potentiation of AIRarg) and insulin sensitivity were obtained.
Twenty individuals, 9 ICA+ relatives and 11 ICA- relatives, were evaluated
prospectively. When expressed in relation to the expected AIRgluc based on
each subject's sensitivity index, AIRgluc in 18 of 20 relatives fell below
100%, indicating inappropriately low insulin secretion (subclinical
beta-cell dysfunction). After a median follow-up of 42 mo, 10 of 11 ICA-
relatives remained ICA-. None showed deteriorating beta-cell dysfunction,
and none developed diabetes. Five ICA+ relatives showed persistent
immunologic positivity. beta-Cell function remained remarkably stable in
all except 2 relatives. One was a 15-yr-old boy who developed IDDM shortly
after screening and before evaluation of beta-cell function could be
carried out. The other was an 18-yr-old monozygotic twin who developed IDDM
after 27 mo. Both of these individuals had ICAs of 80 Juvenile Diabetes
Foundation U and had been discordant for less than 5 yr.(ABSTRACT TRUNCATED
AT 250 WORDS)