In clinical trials, a small increase in LDL cholesterol has been reported with sodium-glucose cotransporter 2 (SGLT2) inhibitors. The mechanisms by which the SGLT2 inhibitor empagliflozin increases LDL cholesterol levels were investigated in hamsters with diet-induced dyslipidemia. Compared with vehicle, empagliflozin 30 mg/kg/day for 2 weeks significantly reduced fasting blood glucose by 18%, with significant increase in fasting plasma LDL cholesterol, free fatty acids, and total ketone bodies by 25, 49, and 116%, respectively. In fasting conditions, glycogen hepatic levels were further reduced by 84% with empagliflozin, while 3-hydroxy-3-methylglutaryl-CoA reductase activity and total cholesterol hepatic levels were 31 and 10% higher, respectively (both P < 0.05 vs. vehicle). A significant 20% reduction in hepatic LDL receptor protein expression was also observed with empagliflozin. Importantly, none of these parameters were changed by empagliflozin in fed conditions. Empagliflozin significantly reduced the catabolism of 3 H-cholesteryl oleate-labeled LDL injected intravenously by 20%, indicating that empagliflozin raises LDL levels through reduced catabolism. Unexpectedly, empagliflozin also reduced intestinal cholesterol absorption in vivo, which led to a significant increase in LDL-and macrophage-derived cholesterol fecal excretion (both P < 0.05 vs. vehicle). These data suggest that empagliflozin, by switching energy metabolism from carbohydrate to lipid utilization, moderately increases ketone production and LDL cholesterol levels. Interestingly, empagliflozin also reduces intestinal cholesterol absorption, which in turn promotes LDL-and macrophage-derived cholesterol fecal excretion.Specific sodium glucose cotransporter (SGLT) inhibitors represent an emerging and promising new class of glucoselowering drugs in the management of type 2 diabetes. The unique mode of action of this class of novel agents can effectively decrease blood glucose levels, independently of the insulin pathway, via increasing glucose excretion in urine, i.e., glucosuria (1,2). Besides improved glycemic parameters, SGLT2 inhibitors have shown additional benefits such as body weight loss and blood pressure-lowering, with low risk of hypoglycemia (3). However, an increase in LDL cholesterol (LDL-C) plasma levels has also been observed in patients treated with SGLT2 inhibitors (1). The mechanism by which SGLT2 inhibition raises LDL-C levels remains unclear. It has been suggested that the increase in LDL-C may be partly due to hemoconcentration, as SGLT2 inhibitors induce volume contraction subsequent to increased urinary volume (4,5). However, the transient diuretic effect of SGLT2 inhibitors may not completely contribute to the observed LDL-C increase. We therefore investigated the effects of the SGLT2 inhibitor empagliflozin in the diet-induced insulin-resistant dyslipidemic golden Syrian hamster, a validated preclinical model with cholesterol metabolism similar to that of humans (6,7).
RESEARCH DESIGN AND METHODSAll animal protocols ...