Prediction of type 1 diabetes mellitus in first degree Czech relatives of diabetic patients

Diagnosis of autoimmune beta cell destruction by genetic risk analysis, autoantibody evaluation and the test of stimulated insulin secretion performance in first-degree relatives of diabetic patients. 208 Czech children and adults (101 boys and 107 girls, 186 siblings, 22 offspring of diabetic parents, aged 1-22 years, mean age 11.5 +/- 5.4 years) were enrolled in the study. Complete DQB1, DQA1 typing and DRB1*04 subtyping were performed by the PCR in 202 subjects. Sera of all children were investigated for anti-GAD65, anti-IA2 and insulin antibodies using RIA methods. The cut-off normal levels were determined as the 99th percentile of 105 non-diabetic children. IVGTT was performed in children with significant titre of one or more autoantibodies. Total level of stimulated insulin secretion < 48 mU/l was assessed as defect of FPIR. Risk genotype DQA1*05-DQB1*0201/DQA1*03-DQB1*0302 (OR = 100, CI 95% 13-730) was found in 24 of 202 first-degree relatives (12%). 22 children (11%) carried strong protective allele DQB1*0602 (OR = 0.03, CI 95% 0.01-0.12). Autoantibody positivity was recognised in 9 of 208 children (2.9%) and IVGTT was performed. Positivity of anti-GAD65, anti-IA2 or IAA was identified in 5 of 24 children with the highest risk genotype (21%) and in 4 children of 113 with lower risk or neutral genotypes (3.5%). Borderline positivity of one autoantibody was found in 1 boy with the highest risk genotype and in 2 children with lower risk genotypes. Only temporary anti-GAD65 positivity was found in girl with protective genotype. Type 1 diabetes mellitus was diagnosed in boy during IVGTT and disease manifested 6 months after IVGTT in girl with defect of FPIR. Standardised methods for prediction of Type 1 diabetes were introduced in first-degree relatives of diabetic patients. These methods are used for Czech registry of diabetic children.