We traced 105 of 140 siblings of children with insulin-dependent diabetes (IDD) who had had oral glucose tolerance tests (OGTT) 10–12 yr earlier. Siblings with abnormal tests by screening criteria (8.3 mmol/L at 1 h, 7.2 at 2 h, N = 44) included all 6 who subsequently developed IDD after 3 mo to 7 yr (5.7% of entire group, 13.6% of abnormal screenees). The National Diabetes Data Group criterion for children (7.8 mmol/L at 2 h) identified 19 siblings, including 5 of the 6 who later developed IDD (26% of abnormals). Subsequent full 4-h OGTT, including analysis of insulin responses, did not improve predictability for subsequent IDD. Thus, siblings of IDD were identified at high risk (14–26%) or at low risk (0–1%) for subsequent IDD by a simple 2-h OGTT. The prolonged latency in the development of IDD indicates that, among siblings of IDD, this disorder may be already chronic for years by the time of clinical onset.

This content is only available via PDF.