Type-2 Diabetes Family History Delays the Onset of Type-1 Diabetes

Abstract

Type-1 diabetes (T1D) is an autoimmune disease leading to insulin deficiency. Itsoccurrence is influenced by genetic and environmental factors. The humanleukocyte antigen (HLA) region on chromosome 6 accounts for 45% of the geneticsusceptibility for the disease, mainly the HLA-DQB1*0201 and HLA-DQB1*0302alleles. Among the environmental factors involved, early exposure to cow's milkseems to be a trigger. In this study, we investigated the occurrence of T1D in253 Lebanese Caucasian patients, in relation to HLA-DQB1*0201, HLA-DQB1*0302,HLA-DQB1*0602, gender, and early exposure to cow's milk, as well as to familyhistory of T1D and type-2 diabetes (T2D). Our genetic analysis results show that in the patients studied, 77% and 40% were positive for BQ1*0201 and BQ1*0302,respectively. As for BQ1*0602, only 0.8% of patients were positive for this T1Dprotective allele, compared with 24% among the controls. Furthermore, our resultsdid not show any gender preference of the disease or any effects of early intake of cow's milk on the age at onset of T1D. When family history of T2D or T1D wasstudied, our results show a novel finding whereby an immediate family history of T2D, but not T1D, delays the age at onset of T1D.