[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.