Development of diabetes mellitus associated with quetiapine: A case series

We aimed to describe the characteristics and clinical course of patients who developed diabetes associated with the use of quetiapine. This study included patients who received quetiapine for over a month between April 2008 and November 2013, and were diagnosed as having new-onset diabetes after initiation of quetiapine. We excluded patients who developed diabetes more than 1 year after discontinuation of quetiapine. We identified new-onset diabetes by hemoglobin A1c or prescriptions of antidiabetic drugs. Among 1688 patients who received quetiapine, hemoglobin A1c had been measured in 595 (35.2%) patients at least once during the observation period, and 33 (2.0%) patients had received hypoglycemic drugs. Eighteen (1.1%) patients were considered to have developed new-onset diabetes associated with quetiapine after a median of 1.6 years following initiation of quetiapine. Median (interquartile range) age was 54.5 (29.8) years, 8 patients were male, and median (interquartile range) duration of mental illness was 15.3 (13.8) years. Median hemoglobin A1c and body mass index (BMI) were 7.1 (1.4) % and 28.4 (7.0) kg/m(2), respectively. Seventeen patients had dyslipidemia when diabetes was discovered. All of these discontinued quetiapine within 3 months after the diagnosis of diabetes, and the diabetes in 4 patients had ameliorated without hypoglycemic drugs. Of 13 patients who had received either oral hypoglycemic drugs or insulin, 2 patients achieved well-controlled hemoglobin A1c without hypoglycemic drugs, and 10 patients had hemoglobin A1c 5.0% to 7.7% with the continued use of hypoglycemic drugs. We demonstrated that almost all patients who developed quetiapine-associated diabetes had dyslipidemia and increased BMI. There was no life-threatening hyperglycemia and diabetes was ameliorated just by discontinuation of quetiapine in several patients. The monitoring of metabolic parameters during antipsychotic treatment is important to diagnose and treat diabetes earlier.