LEP and obesity due to melanocortin 4 receptor deficiency: Currently, we investigate the association of leptin, sOBR and free leptin index (FLI, a marker of leptin activity) with mild cognitive impairment stratified by body weight status (normal, overweight and obese by BMI) in diabetic patients to explore whether leptin, sOBR, and obesity may be better predictive markers and therapeutic target for diabetic patients with MCI.