Issue 118 Item 12 History of Type 2 Diabetes Delays Onset of Type 1 Diabetes

Results of a study published in the July issue of The Journal of Clinical Endocrinology and Metabolism indicate that a family history of type 2 diabetes delays the onset of type 1 diabetes. Dr. Sami T. Azar, of the American University of Beirut, in Lebanon, and colleagues studied 253 patients with type 1 diabetes in relation to HLA-DQB1 haplotype, gender, and early exposure to dairy products. They also studied occurrence of the disease in relation to family history of type 1 and type 2 diabetes.

"In accordance with the reported literature," the patients had a higher occurrence of the *0201 and *0302 alleles of HLA-DQB1, the investigators report, and a much lower frequency of the protective *0602 allele, compared with nondiabetic controls.

Dr. Azar and colleagues observed no effect of early intake of cow’s milk on the age of onset of type 1 diabetes, and no gender preference.

However, when they examined family history of diabetes, they found that a history of type 2 diabetes was associated with a delay in the age of onset of type 1 diabetes. Mean age at onset was 13 years in patients with an immediate family history of type 2 diabetes, compared with 8 years in those with no such family history (p < 0.001).

"Studying families with simultaneous presence of type 1 diabetes and type 2 diabetes may prove important in understanding the genetic predisposition to type 1 diabetes as well as the genetic and environmental factors involved in the onset of the disease," the researchers suggest. J Clin Endocrinol Metab 2002;87:3192-3196.