Impaired insulin secretion in non-diabetic offspring of probands with latent autoimmnne diabetes mellitus in adults

Aims/hypothesis. This study was undertaken to investigate metabolic and gen etic characteristics of latent autoimmune diabetes in adults (LADA). Methods. We evaluated insulin secretory capacity with oral and intravenous glucose tolerance tests (early insulin response) and hyperglycaemic clamp ( insulin secretory capacity) and the rates of whole body glucose uptake with the euglycaemic clamp, HLA-DQB1 genotypes (time-resolved fluorescence) and islet cell antibodies (ICA) (immunofluoresence) and antibodies to glutamic acid decarboxylase (GAD) (radio-immunoprecipitation) in 36 non-diabetic of fspring (LADA-offspring) of patients with Type II (non-insulin-dependent) d iabetes mellitus who tested positive for ICA and/or GAD antibodies during t he 10-year follow-up from the diagnosis and in 19 healthy control subjects without a family history of diabetes. Results. The early insulin response during the first 10 min of an intraveno us glucose tolerance test was about 40% lower in the LADA-offspring than in the control group (p = 0.008). Insulin secretory capacity in the hyperglyc aemic clamp was also about 30% lower in the LADA-offspring (p = 0.048). The rates of whole body glucose uptake were similar in both groups. The freque ncy of low risk HLA-DQB1 genotypes was higher in the LADA-offspring than am ong Finnish healthy blood donors (p = 0.033). The risk conferring genotypes were associated with the lowest tertile of insulin secretory capacity in t he LADA-offspring (p = 0.032). There were no associations between the autoa ntibodies and early insulin response or insulin secretory capacity within t he study groups. Conclusion/interpretation. We conclude that LADA is a familial disease invo lving most likely gene defects leading to a slow progressive beta-cell dest ruction and insulin deficiency.