Conversely, our investigation unveiled significant findings, such as diminished serum asprosin and PYY levels in BD-I patients relative to control subjects, with the most pronounced reductions observed in the BD-M group, suggesting that PYY may serve as a status marker for manic episodes, alongside elevated levels of BMI, fasting blood sugar, and triglycerides—precursors to metabolic disorders—in BD-I patients. Here, PYY is linked to metabolic disease.