These data suggest PTH as the major predictor of immune deviance towards the Th1 response in both type 1 diabetic subjects and their siblings. Considering that the active form of vitamin D suppresses PTH production, it is hypothesised that vitamin D replenishment of just those who are genetically prone to the disease (i.e. siblings) may be regarded as a preventive measure against T1D.

BACKGROUND/OBJECTIVES: Oxidative stress (OS) is thought to be involved in both development of type 1 diabetes (T1D) and its further complications. In this study, certain biomarkers of OS were compared among the subjects with T1D, their non-diabetic siblings and unrelated healthy controls. SUBJECTS/METHODS: Known cases of T1D from both sexes aged 5-25 years were enrolled in a case-control study (n 1 ¼ 60). There were two control groups; non-diabetic siblings (n 2 ¼ 60) and unrelated apparently healthy subjects (n 3 ¼ 60). Anthropometric, dietary and laboratory assessments were done. RESULTS: There was no significant difference in dietary data among the groups. Total antioxidant capacity was significantly lower in T1D than both related and unrelated controls (1.6±0.05, 1.7±0.05 and 1.8±0.06 mmol BSA equivalent/l, respectively, P ¼ 0.044). Both T1D subjects and their siblings showed lower glutathione peroxidase (GSH-px) levels (median (interquartile range): 22.2 (28.6), 29.9 (23) and 41.8 (73.6) U/ml, respectively, P ¼ 0.006). On the contrary, superoxide dismutase concentrations were significantly higher in T1D group and the siblings than unrelated healthy controls (243 (45.3), 157.8 (176.9) and 27.9 (8.7) U/l, respectively, Po0.001). Serum concentrations of GSH correlated with energy intake in the siblings (r ¼ 0.521, Po0.001) and unrelated controls (r ¼ 0.268, P ¼ 0.042) but not in T1D group. The associations remained significant after controlling for blood glucose (r ¼ 0.437, P ¼ 0.001 and r ¼ 0.420, P ¼ 0.011, respectively) in both the groups. CONCLUSION: Augmented OS in the siblings may indicate an increased requirement for antioxidants in genetically diabetes-prone subjects.