Delayed Diabetes Treatment and Persistent Hyperglycemia among Individuals with Schizophrenia: a Nationwide Register-Based Study.

BACKGROUND AND HYPOTHESIS: Individuals with schizophrenia are at increased risk of type 2 diabetes and diabetes-related complications. Whether the detection of hyperglycemia in individuals with schizophrenia is followed by timely clinical action remains insufficiently understood. We hypothesized that glucose-lowering drug (GLD) treatment would be initiated later in individuals with schizophrenia with elevated glycated hemoglobin (HbA1c) than in matched individuals without schizophrenia, and that this delay would be reflected in worse HbA1c trajectories. STUDY DESIGN: We identified all individuals with schizophrenia aged ≥30 years at the time of the first elevated HbA1c (≥48 mmol/mol) in nationwide Danish registers. These individuals were matched on age, sex, year of elevated HbA1c, and baseline HbA1c with up to five individuals without schizophrenia. In the year following the detection of elevated HbA1c, we compared time to GLD treatment between individuals with and without schizophrenia using a Cox proportional hazard model. Mean HbA1c levels over time were illustrated graphically and compared using linear mixed-effects models. STUDY RESULTS: We identified 1527 individuals with schizophrenia and 7492 matched comparison individuals. In the year following detection of elevated HbA1c, schizophrenia was associated with a slower rate of GLD treatment initiation (hazard rate ratio [HRR] = 0.88, 95% confidence interval [CI]: 0.81-0.94). Consistently, HbA1c decreased more slowly among individuals with schizophrenia. Notably, schizophrenia was associated with a slower rate of GLD treatment initiation among males (HRR = 0.82, 95%CI: 0.74-0.90) but not females (HRR = 0.99, 95%CI: 0.87-1.11). CONCLUSIONS: Schizophrenia was associated with a slower rate of GLD treatment initiation and slower reductions in HbA1c following detection of elevated HbA1c, particularly among males.