Altered metabolic parameters in association with antipsychotic medication use in diabetes: A population based case-control study.

Aims: This study assess differences in clinical variables in diabetes patients prescribed antipsychotic medication and determines relative schizophrenia prevalence in the diabetes population.

Methods: This population-based case-control study utilizing Scotland's national diabetes registry (SCI-diabetes) and linked psychiatric hospital discharge data (SMR04) established diabetes phenotypes in a patient cohort prescribed long term antipsychotic medication (n=2362) (cases). Cases were matched 1:10 to diabetes patients not prescribed antipsychotic medication (controls) for BMI, gender; diabetes type; birth year; diagnosis date; smoking status. Sub-groups with defined schizophrenia (n=196) or bipolar disorder (n=190) were further examined. Schizophrenia prevalence in the diabetes versus general population was compared.

Results: During follow up, antipsychotic prescription was associated with lower HbA1c (55.1 (95% CI 54.5-55.8) or 7.2 (95% CI 7.1-7.3)% vs 58.2 (58.0-58.4) mmol or 7.5 (95% CI 7.5-7.5)% p<0.001) lower serum total cholesterol, 4.2 (4.1-4.2) vs 4.3 (4.2-4.3) mmol/l, p<0.001, lower blood pressure (systolic 130 (130.17-131.29) vs 134 (134.3-134.7) mmHg, p<0.001), higher prescription of oral hypoglycaemic medication (42% (40-45) vs 38% (37-39) p<0.001), similar statin prescriptions (85% (81-89) vs 85% (84-86), p=0.55), and lower retinopathy rates (28% (25.6-30.5) vs 32% (31.5-33.1), p<0.001). HbA1c at diagnosis was similar (p=0.27). Schizophrenia prevalence was higher in the diabetes versus general population with differences across age groups (Scottish population versus diabetic population rate of 522.2 (522.1-522.3) versus 717.4 (703.4-731.9) per 100,000).

Conclusions: We confirm higher diabetes rates in schizophrenia up to age 70, similar attendance rates and clinical measurements that are not worse in a large well-matched population-based Scottish sample prescribed antipsychotic medication versus matched general diabetes patients.