RESUMO
RATIONALE: Olanzapine (OLZ) is known to cause weight gain and metabolic disturbances, which may have serious implications with respect to medical comorbidities such as metabolic syndrome and insulin resistance. OBJECTIVES: The aim of this study was to evaluate the effects of two angiotensin II type 1 receptor blockers (ARBs) which are widely used as antihypertensive agents, valsartan (VAL) and telmisartan (TEL), on insulin resistance in patients with schizophrenia treated with OLZ. METHODS: Thirty inpatients with schizophrenia with OLZ monotherapy over 8 weeks participated in this study. To assess insulin resistance, the homeostasis model assessment of insulin resistance (HOMA-IR), fasting plasma glucose (PG) levels and immunoreactive insulin (IRI) levels were measured [HOMA-IR = fasting PG level (mmol/L) x fasting IRI level (µU/ml)/22.5]. VAL add-on treatment was performed in insulin-resistant patients (HOMA-IR > 1.6) for 12 weeks. After a 12-week VAL washout period, TEL add-on treatment was carried out for 12 weeks. The effects of ARBs on insulin resistance and other metabolic variables were assessed. RESULTS: In all 30 patients, both body mass index and abdominal circumference were strongly correlated with HOMA-IR. Twelve patients showed high HOMA-IR and were deemed to be insulin resistant. Add-on therapy of VAL and TEL resulted in a significant decrease in fasting IRI levels and HOMA-IR. No differences in any effects were observed between VAL and TEL. No adverse effects of either ARBs were observed in this study. CONCLUSIONS: ARBs for patients treated with OLZ improved insulin sensitivity and attenuated insulin resistance.
