Testing for diabetes in hospitalised patients prescribed antipsychotic drugs.

BACKGROUND Studies using computer databases suggest that atypical antipsychotic agents are more likely to be associated with diabetes than are conventional drugs. AIMS To discover the extent of testing for diabetes mellitus in hospital in-patients prescribed antipsychotics. METHOD Prescription charts were screened to identify patients prescribed antipsychotics. Case notes were then searched for evidence of testing for diabetes. RESULTS In all, 606 patients were prescribed antipsychotics, of whom 250 (41.3%) had evidence of prior testing for diabetes. Patients prescribed atypicals were 40% more likely to have been tested than those prescribed conventional drugs (RR =1.4,95% CI1.1-1.9). Adjusted odds ratios v. conventional antipsychotics for conventional antipsychotics for testing were significantly higher for clozapine (OR=4.64,95% CI 2.42-8.90), olanzapine (OR=1.85,95% CI1.04-3.30) and antipsychotic polypharmacy (OR=2.96,95% CI1.59-5.52). CONCLUSIONS Testing for diabetes was undertaken in less than half of the patients studied. Testing was more common in those receiving atypical antipsychotics. Apparent differences in claimed causal association of the use of some antipsychotics with diabetes may in part reflect different rates of testing.