Prevalence of Diabetes Mellitus and Impaired Fasting Glucose among Patients with Severe Mental Illnesses Treated with Antipsychotic Medications

Objectives: The study aimed to compare the diabetogenic risk p otential between conventional and atypical antipsychotic medications after at least one year t reatment and between specific diagnoses of schizoph renia vs. bipolar affective disorder. Methods: This was a retrospective study of patients receivin g conventional antipsychotic medications or atypical antipsychotic for people with schizophreni a or bipolar affective disorder at psychiatry depar tment of the Royal Medical Services of Jordan. Out of 1100 c ase records, 199 patients fulfilled our initial cri teria of inclusion of being treated for at least one year. Of these 138 were receiving conventional antipsychotic while 61 were treated with atypical antipsychotic. Patien ts with known overt diabetes mellitus before treatm ent were excluded from each group, leaving 132 and 57 cases for conventional antipsychotic, atypical antipsycho tic respectively for analysis. The following parameters were analyzed: Age, diagnosis, the mean of at leas t two fasting blood sugar readings at the time when antip sychotic medications were started, and at the end o f at least one year treatment looking for diabetes mellitus (f asting blood sugar > 126 mg/dl) or impaired fasting glucose (fasting blood sugar between 100 - 125mg/dl), and f amily history of diabetes mellitus. Results: Mean age for conventional antipsychotic was 37.63±12.77 years vs. 34.10± 13.17 years for atypical antipsychotic (P= 0.086). Male: female ratio= 2:1 f or both groups. Family history of diabetes mellitus was present in 33.3% in the conventional antipsychotic group vs. 21 % in the atypical antipsychotic group (P= 0.043). In the conventional antipsychotic group imp aired fasting glucose was 13.6% after at least one year of treatment vs. 15.8% in atypical antipsychotic group (P= 0.3). New cases of diabetes mellitus were fou nd in 10.6% in the conventional antipsychotic group vs. 7 % in the atypical antipsychotic group (P= 0.2119). The mean fasting blood sugar before vs. after treatment was 86.93± 9.92 vs.101.89± 47.80 in conventional antipsychotic (P= 0.0002), and 88.94±11.41 vs. 105. 98±70.79 in atypical antipsychotic group (P= 0.03). In the conventional antipsychotic group new onset case s of diabetes mellitus in bipolar affective disorde r were 13.5% vs. 9.4% in schizophrenics (P= 0.3). In the atypical antipsychotic group new onset cases of dia betes mellitus were 5.12% among schizophrenics vs. 11.11% among bipolar affective disorder group (P= 0.28). Conclusion: Statistically significant difference between the me an fasting blood sugar at treatment onset compared to the mean fasting blood sugar after at l east one year treatment in both patient groups was found. No significant difference in the new onset diabetes cases between both groups, neither in relation to specific diagnosis were found. The treatment with both types of conventional and atypical antipsychotics did no t seem to increase glycaemic abnormalities above that of t he general population rates in Jordan.