Objective: The aim of this study was to investigate the association between family history of diabetes (FHD) and prevalence and incidence of latent autoimmune diabetes of the adult (LADA), type 1 diabetes, and type 2 diabetes.
Research design and methods: The results were based on cross-sectional data from 64,498 men and women (aged >or=20 years) who were in the Nord-Trøndelag Health Study, which included 128 cases of LADA, 1,134 cases of type 2 diabetes, and 123 cases of type 1 diabetes. In addition, prospective data on 46,210 subjects, which included 80 incident cases of LADA, observed between 1984 and 1986 and 1995 and 1997 were available. Patients with LADA had antibodies against GAD and were insulin independent at diagnosis.
Results: FHD was associated with a four times (odds ratio [OR] 3.92 [95% CI 2.76-5.58]) increased prevalence of LADA. Corresponding estimates for type 2 and type 1 diabetes were 4.2 (3.72-4.75) and 2.78 (1.89-4.10), respectively. Patients with LADA who had FHD had lower levels of C-peptide (541 vs. 715 pmol/l) and were more often treated with insulin (47 vs. 31%) than patients without FHD. Prospective data indicated that subjects with siblings who had diabetes had a 2.5 (1.39-4.51) times increased risk of developing LADA during the 11-year follow-up compared with those without.
Conclusions: This study indicates that FHD is a strong risk factor for LADA and that the influence of family history may be mediated through a heritable reduction of insulin secretion.