[Familial study for the early diagnosis of insulin-dependent diabetes mellitus].

Background: Diabetes is more frequently found than expected in families of first grade with children with diabetes type I.

Methods: With the aim of identifying the potential candidates prone to develop diabetes type I, genetic and metabolic analysis was carried out on the members of 11 families with a diabetic type I child. They were distributed into three groups: 11 diabetic patients (IDDM); 22 progenitors and 13 unaffected siblings. The HLA haplotype was determined, the spectrum of autoantibodies and the intravenous glucose tolerance test (IVTT) were performed.

Results: In two progenitors postprandial glycemia values corresponding to intolerance to carbon hydrates were obtained. Moreover, in one the IVTT was found to be low in the normal values. Of a total of 12 non diabetic descendents studied, 4 shared identical HLA haplotypes as the diabetic, 5 were haploidentical and 3 unidentical. The DR 3 antigen was detected in 90% of the diabetics; in 68% of the progenitor group and in 50% of the non diabetic descendents. Sixty-two percent of the children inherited the DR 4 antigen of the father (p less than 0.05), while 37% do so from the mother. Of the siblings with a haplotype identical to that of the diabetic, 2 were also ICA positive; asymptomatic at the moment of the study but in one the diabetes type I became manifest after 2 years of evolution.

Conclusions: Subjects at high risk of becoming type I diabetics may be identified at a preclinical phase by means of HLA typing and the detection of immunologic and metabolic markers associated with the disease.