Diabetes, Vol 40, Issue 7 831-836, Copyright © 1991 by American Diabetes Association
Risk of diabetes in siblings and other relatives of IDDM subjects
C Allen, M Palta and DJ D'Alessio
Department of Preventive Medicine, School of Medicine, University of Wisconsin, Madison 53705.
The risk of insulin-dependent diabetes mellitus (IDDM) was examined in
siblings of an unselected population (n = 194) of newly diagnosed diabetic
individuals less than 30 yr old. From 1 July 1984 to 30 June 1987, diabetic
subjects (proband) identified within a geographically defined area of
southern Wisconsin were studied. IDDM occurred among siblings of probands
in 13.5% of families and was associated with proband age at diagnosis. The
highest risk was found for diabetic subjects less than 10 yr old at
diagnosis (P = 0.04). We did not find an association between sibling IDDM
and proband sex, HLA-DR3/4, duration of symptoms, or ketosis at diagnosis.
In addition, the odds ratio (OR) for the association of IDDM in the proband
with IDDM in parents and second- and third-degree family members was
examined by case-control methodology. Diabetic subjects were matched to two
types of control subjects (friends and general population) by age stratum
and sex. The OR for IDDM was not increased significantly if parental IDDM
or non-insulin-dependent diabetes mellitus (NIDDM) was reported. However,
there were very few parents with diabetes among diabetic or control
subjects. In 6.4% of diabetic subjects, one parent had IDDM, 54% of whom
were fathers. In 4.3% of diabetic subjects, one parent had NIDDM, and 57.1%
of these were fathers. The OR for IDDM was significantly increased if
second- and/or third-degree relatives had IDDM (OR diabetic subjects vs.
general population 2.33 [P less than 0.05)] or NIDDM (OR diabetic subjects
vs. friends 2.05 [P less than 0.01]).(ABSTRACT TRUNCATED AT 250 WORDS)