Despite the GIP conundrum, the first approved GIP receptor/GLP-1 receptor co-agonist tirzepatide has confirmed the efficacy gains of the dual agonism effect: placebo-subtracted decreases in HbA1c >22 mmol/mol (>2%) and body weight >8 kg were achieved during 40 week clinical trials in participants with overweight/obesity and type 2 diabetes [53]. The gene discussed is GIP; the disease is obesity due to melanocortin 4 receptor deficiency.