Levels of Metrnl proteins are increased in individuals diagnosed with type 2 diabetes and obesity [[15], [16], [17]], with a positive correlation between serum concentrations of Metrnl and metabolic indicators such as BMI, waist circumference, fasting blood glucose, Hemoglobin A1c (HbA1c), and HOMA-IR [17]. This evidence concerns the gene METRNL and obesity due to melanocortin 4 receptor deficiency.