374-P: Identifying the Role and Mechanism by Which GDF15 Enhances the Counterregulatory Response to Hypoglycemia

Abstract

Severe hypoglycemia is the leading acute mortality risk in patients with diabetes. The counterregulatory gluconeogenic and glycogenolytic response to hypoglycemia is the primary adaptive mechanism to enable survival. To better understand the hormonal response that orchestrates hypoglycemia counterregulation, we employed the insulin tolerance test (ITT) and hyperinsulinemic-hypoglycemic clamp to mimic the two common settings in which hypoglycemia can occur in patients: postprandial insulin overdose and elevated basal insulin infusion, respectively. We found that Growth Differentiation Factor 15 (GDF15) can be induced (33.5±2.1 vs. 172.4±29.2 pg/ml, P<0.in ITT and 46.2±11.6 vs. 2865±547.3 pg/ml, P<0.0in the clamp) . GDF15 mRNA and protein are upregulated in kidney, and the GDF15 tdTomato reporter mouse demonstrates the expression of GDF15 in the S3 segment of the proximal tubule. GDF15 increases hepatic gluconeogenesis (26.1±2.2 vs. 33.5±1.6 mg/kg/min, P<0.05) by increasing intrahepatic lipolysis in a beta-adrenergic receptor-2 (Adrb2) -dependent manner. To investigate the role of GDF15 counterregulation in diabetes, we utilized a streptozotocin (STZ) -induced type 1 diabetes (T1D) model. Mice with T1D exhibit impaired GDF15 production in an ITT. Additionally, we found that recurrent hypoglycemia impairs endogenous glucose production during hypoglycemia in mice (27.5±4 vs. 10.5±1.3 mg/kg/min, P<0.01) , which may result from lower GDF15 production (1372±248.2 vs. 648.5±71.3 pg/ml, P<0.05) . In humans, hypoglycemic clamps in healthy volunteers can induce GDF15 production (p=0.01) , although this induction was absent in patients with T1D. Conclusion: These data show the kidney can produce GDF15 in response to hypoglycemia, thereby increasing hepatic gluconeogenesis to enable survival. However, T1D patients are unable to initiate a functional GDF15 signaling pathway resulting in an impaired glucose counterregulatory response to hypoglycemia. Disclosure Z.Li: None. C.Zhang: None. R.Chang: None. J.J.Hwang: None. A.Wang: Research Support; NGM Biopharmaceuticals. R.J.Perry: None. X.Zhang: None. W.Zhu: None. Q.Xu: None. C.Yu: None. B.G.Costa lima: None. X.Li: None. K.Israni-winger: None. A.Nasiri: None. Funding National Institutes of Health (P30 DK045735) National Institutes of Health (R37 CA258271-01A1)