Modestly increased beta cell apoptosis but no increased beta cell replication in recent-onset type 1 diabetic patients who died of diabetic ketoacidosis

Abstract

Aims/hypothesis: Type 1 diabetes is characterised by a deficit in beta cell mass thought to be due to immune-mediated increased beta cell apoptosis. Beta cell turnover has not been examined in the context of new-onset type 1 diabetes with diabetic ketoacidosis.

Methods: Samples of pancreas were obtained at autopsy from nine patients, aged 12 to 38 years (mean 24.3+/-3.4 years), who had had type 1 diabetes for less than 3 years before death due to diabetic ketoacidosis. Samples of pancreas obtained at autopsy from nine non-diabetic cases aged 11.5 to 38 years (mean 24.2+/-3.4 years) were used as control. Fractional beta cell area (insulin staining), beta cell replication (insulin and Ki67 staining) and beta cell apoptosis (insulin and TUNEL staining) were measured.

Results: In pancreas obtained at autopsy from recent-onset type 1 diabetes patients who had died of diabetic ketoacidosis, the beta cell deficit varied from 70 to 99% (mean 90%). The pattern of beta cell loss was lobular, with almost all beta cells absent in most pancreatic lobules; islets in lobules not devoid of beta cells had reduced or a near-normal complement of beta cells. Beta cell apoptosis was increased in recent-onset type 1 diabetes, but to a surprisingly modest degree given the marked hyperglycaemia (30 mmol/l), acidosis and presumably high NEFA. Beta cell replication, scattered pancreatic beta cells and beta cells in exocrine ducts were not increased in recent-onset type 1 diabetes.

Conclusions/interpretation: These findings do not support the notion of active beta cell regeneration by replication in new-onset type 1 diabetes under conditions of diabetic ketoacidosis. The gluco-lipotoxicity reported in isolated human islets may be less evident in vivo.