Assessment of insulin resistance and metabolic syndrome in drug naive patients of bipolar disorder.

The levels of fasting glucose, fasting insulin, insulin resistance (IR) and the prevalence of metabolic syndrome (MS) in a sample population of bipolar disorder (BPD) patients who were newly diagnosed and psychotropically naïve were assessed and compared with an age, sex and racially matched control population. 55 BPD-I patients (15-65 years) who were non-diabetic, nonpregnant, and drug naïve for a period of at least 6 months were included in the study. Diagnosis was made using the structured clinical interview for DSM-IV axis I disorders (SCID IV). IR was assessed using homeostasis model of insulin resistance (HOMA-IR); MS was defined according to National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III). Data were compared with 25 healthy controls. BPD patients had significantly higher mean levels of fasting plasma insulin (13.2 ± 9.2 vs. 4.68 ± 3.1 µIU/ml, p < 0.05), postprandial plasma insulin (27.2 ± 14.5 vs. 18.1 ± 9.3 µIU/ml, p < 0.05) and a higher value of HOMA-IR (3.16 ± 2.2 vs. 1.19 ± 0.8, p < 0.05) when compared to the controls. A significantly higher proportion of patients of BPD compared to controls were manifesting levels of fasting plasma glucose, serum triglyceride and blood pressure higher than the cut off while waist circumference and serum HDL cholesterol failed to show any significant difference in the proportion. There was a significantly higher proportion of prevalence of IR between BPD cases and controls (26/55 vs. 2/25, z value 9.97, p < 0.05) while there was no significant difference in proportion of prevalence of MS between these two groups. Within BPD patients, logistic regression analysis showed that age, sex or current mood status (depressed/manic) were not significantly predictive of presence or absence of MS or increased IR.