As a dual GLP-1 receptor and GIP agonist, Tirzepatide (TZP) induces weight loss and improves glycemic control in patients with type 2 diabetes. Here, we performed insulin clamp and glucagon clamp under euglycemic conditions in male C57BL/6J mice fed a high-fat diet (HFD; 12 weeks) after once-daily treatment with TZP (3 nmol/kg) or GIP (25 nmol/kg) for 5 days (n=5). TZP and GIP caused HFD-fed mice to lose 10~15% of weight, but their fat mass remained 7-fold higher than chow-fed controls (C) (Fig. 1). Insulin clamp showed that GIP caused a 37% decrease in hepatic insulin action in chow-fed mice (Fig. 2). In HFD-fed mice, TZP induced significant increases in hepatic insulin action (4-fold) and glucose turnover (25%) compared to GIP, restoring insulin sensitivity to levels comparable to controls (Fig. 2-3). TZP also increased glucose metabolism in brown fat (1,528±155 vs. 798±166 nmol/g/min in GIP). Glucagon clamp showed that TZP significantly reduced hepatic glucose production (HGP) by ~50% compared to controls and GIP (Fig. 4). CONCLUSION: These data indicate that TZP improves insulin action and reduces hepatic glucagon action in obese mice while GIP causes hepatic insulin resistance in lean mice. Our findings suggest that TZP’s glycemic control may involve amelioration of insulin resistance and glucagon resistance, independent of weight loss and GIP action in the liver.
B.Kim: None. L.A.Tauer: None. X.Hu: None. J.K.Kim: None.
National Institutes of Health (5U2CDK093000)
