Influence of Family History of Diabetes on Incidence and Prevalence of Latent Autoimmune Diabetes of the Adult (lada)

OBJECTIVE The aim of this study was to investigate the association between family history of diabetes (FHD) and prevalence and incidence of LADA, type 1 and type 2 diabetes. RESEARCH DESIGN AND METHODS The results were based on cross-sectional data from 64,498 men and women ≥20 years in the Nord-TrØndelag Health Study, including 128 cases of LADA; 1,134 cases of type 2 and 123 cases of type 1 diabetes. In addition, prospective data on 46,210 subjects, including 80 incident cases of LADA, observed between 1984-86 and 1995-97 were available. Patients with LADA had antibodies against GAD and were insulin independent at diagnosis. RESULTS FHD was associated with a 4 times (Odds Ratio (OR) =3.92, 95% CI=2.76-5.58) increased prevalence of LADA. Corresponding estimates for type 2 diabetes and type 1 diabetes were 4.2 (95% CI=3.72-4.75) and 2.78 (95% CI=1.89-4.10), respectively. LADA patients with FHD had lower levels of C-peptide (541 vs. 715 pmol/l) and were more often insulin treated (47 % vs. 31%), than patients without FHD. Prospective data indicated that subjects with siblings with diabetes had a 2.5 (95% CI=1.39-4.51) times increased risk of developing LADA during the 11-year of follow-up compared to 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.