Diabetic ketoacidosis and diabetes associated with antipsychotic exposure among a previously diabetes-naive population with schizophrenia: a nationwide nested case-control study

Aims/hypothesis: Diabetic ketoacidosis (DKA) is a potentially fatal metabolic emergency of both type 1 and type 2 diabetes. Although there is a reduced risk of type 1 diabetes in schizophrenia, the incidence of DKA is tenfold higher than that of the general population. Thus, we aimed to investigate associations between exposure to antipsychotic medication (within 3 months prior to event) and DKA, type 1 diabetes and type 2 diabetes. We also reported related, clinically relevant outcomes.

Methods: Using a nested case-control study design, we identified cases of DKA, type 1 diabetes and type 2 diabetes in a previously diabetes-naive population with schizophrenia in Denmark from 1995 to 2014. Cases were matched (by age, sex and year of schizophrenia onset) 1:5 to schizophrenic control individuals who were alive and had not emigrated prior to event. Conditional logistic regression was used to compute ORs with 95% CIs. Other outcomes included diabetes aetiology of DKA, in-hospital mortality, DKA readmissions and temporal trends of use of insulin and oral glucose-lowering agents.

Results: Of 29,955 individuals with schizophrenia, we identified 28 individuals with DKA, 90 with type 1 diabetes and 2140 with type 2 diabetes. These were matched to 137, 410 and 9861 individuals in the control group, respectively. Antipsychotic exposure was associated with DKA (OR 2.60; 95% CI 1.06, 6.38) and type 2 diabetes (OR 1.64; 95% CI 1.48, 1.83). A trend towards increased risk of type 1 diabetes was found but remained insignificant (OR 1.38; 95% CI 0.84, 2.29). Diabetes aetiology of DKA was type 1 in eight cases and type 2 in 14 cases. Of the remaining six cases of DKA, aetiology could not be determined, as four were fatal within 8 days and for two, no prescriptions for insulin and oral glucose-lowering agents were redeemed. Of all DKA cases, six had more than one episode of DKA, and of all type 1 diabetes and type 2 diabetes cases, four and 11, respectively, had at least one episode. Use of insulin and oral glucose-lowering agents was higher among individuals with DKA relative to those with type 1 diabetes and type 2 diabetes.

Conclusions/interpretation: Antipsychotic exposure was associated with DKA and type 2 diabetes in a previously diabetes-naive schizophrenia population. Antipsychotic-associated DKA is relevant not only for psychiatrists but also for other physicians who may manage and admit such patients.