This paper combines forensic psychiatry, antipsychotics drug and metabolic disturbances. It refers to mentally disordered offenders provided with forensic psychiatric care are often treated with second generation antipsychotic medication and experience metabolic and inflammatory side effects. Three-year variability of selected anthropometric, biochemical and inflammatory markers was monitored in forensic psychiatric patients receiving antipsychotic (AP) medication for more than five years, according to the type of ΑP. Thirty-five patients with psychotic disorders were classified into two groups based on the type of AP. Specifically: AP1, related to a lower risk, and AP2, related to an increased risk of weight gain and metabolic complications. Biochemical, hematological, anthropometric, blood pressure, and medication data were retrieved from the individual medical files. No significant differences in weight and glucose and cholesterol levels were observed, but patients taking AP2 more often needed drugs to control diabetes mellitus, lipidemia, and cardiovascular disease. In those taking AP1, the mean HDL level decreased significantly over time (p < 0.05) and a higher proportion developed higher blood pressure (52.9% of AP1 vs. 16.7% AP2). In the AP2 group the median level of C-reactive protein (p < 0.001) and the white blood cell count increased over the three years (p < 0.001).