Background: Schizophrenia is one of the mental disorder with many problematic issues, in both psychologically and socially. This disease requires provision of long-term antipsychotic therapy, hence could rise other potential health problems. Antipsychotic treatment can cause serious glucometabolic side-effects, including type 2 diabetes and hyperglycemic emergency. Recent attention has also been focused on antipsychotic-induced hyperglycemic emergencies experienced by new users of typical and atypical antipsychotic. Patients treated with atypical APDs have ~10 times higher risk in developing hyperglycaemic emergencies. In our pre-eliminary study, hyperglycemia condition in new patients occurs in four  in seven patients who received typical and atypical antipsychotics. This condition is often overlooked and is not routinely evaluated. Moreover, it can develop into diabetes and increase the risk of morbidity and mortality in schizophrenia patients. In this study, we would like to determine the acute effects of metabolic (hyperglycemia) in patients treated with antipsychotic (Risperidone and Haloperidol) Measurement of blood sugar levels was performed in groups treated with haloperidol (N = 15) and treated with risperidone (N = 15). Plasma samples were taken at the beginning of treatment, in week IV, and in week VIII. The measurement of glucose levels was performed after meal and in early morning before breakfast (fasting blood glucose level 8 hours). Results: The blood sugar level after meals was significantly higher in the Risperidone group compared to the Haloperidol group  (p <0.001) after IV and VIII weeks. Meanwhile, the fasting blood sugar level was significantly higher in the Risperidone group compared to the Haloperidol group after VIII weeks of treatment ( p <0.001). Conclusions: Both antipsychotics can cause an increase in blood sugar levels. Treatment with Risperidone significantly increased the blood sugar levels compared to treatment with haloperidol. Measurement of blood sugar level is needed to monitor the metabolic effect of antipsychotic, especially in patients treated with Risperidone. It is necessary to have dietary regulation and physical activities to prevent undesired metabolic side effects.