Glucose-insulin homeostasis, lipid profiles and GH-IGF-IGFBP axis in clozapine-treated schizophrenic obesity versus non-psychiatric obesity

Objective: Obese patients with schizophrenia being treated with clozapine and non-psychiatric obese are often assumed to share the same physiological changes in obesity. The aim of this study was to identify possible metabolic and hormonal differences between non-psychiatric obese subjects (OB) and obese patients with schizophrenia being treated with clozapine (OSC). Subjects: Fifty-one normal healthy subjects (Nor, body mass index (BMI):23.2±0.3), 50 OB (BMI:31.7±0.7) and 71 OSC (BMI:30.4±0.5). Measurements: Anthropometric, metabolic and hormonal parameters were determined by anthropometry, enzyme autoanalyzer, immunoassay and enzyme-linked immunosorbent assay. Results: Triglyceride, total cholesterol divided by high-density lipoprotein (HDL) cholesterol (TC/HDL) and leptin levels were significantly higher whereas the HDL and the molar ratio of insulin-like growth factor-1 (IGF-1), and insulin-like growth factor binding protein (IGFBP)-3 levels were significantly lower in both OB and OSC groups than those in the Nor group. Compared to normal subjects, insulin and homeostasis model assessment (HOMA) index levels were significantly higher in OSC, and, in OSC, insulin sensitivity and insulin-like growth factor (IGF)-1 were significantly lower. Although the anthropometric parameters in the OB and OSC groups were similar, in the OSC group the waist-to-hip ratio (WHR), insulin levels and HOMA index were significantly higher, while insulin sensitivity, cholesterol, low-density lipoprotein (LDL) cholesterol, TC/HDL, LDL/HDL, IGF-1 and IGF-1/IGFBP-3 molar ratio were lower, than those of the OB group. Conclusion: Insulin homeostasis and lipid profiles in clozapine-treated schizophrenic obesity were different from those in non-psychiatric obesity with similar anthropometric parameters, body weight and BMI. Among the three groups, the highest fasting insulin, the lowest insulin sensitivity and the highest HOMA index occurred in the OSC group. The OSC group was characterized by impaired glucose-insulin homeostasis, abnormal lipid profiles and hormonal changes in the GH-IGF-IGFBP axis and in leptin.