GPC4 and obesity due to melanocortin 4 receptor deficiency: Of greater significance, serum levels of glypican-4 have been found to be linked to key metabolic indicators such as the ratio of visceral to subcutaneous fat area, fasting plasma insulin (FINS) and the homeostasis model assessment of insulin resistance (HOMA-IR), highlighting its potential as a biomarker for metabolic disorders associated with obesity and IR (10, 11).