Brief Summary:
To examine the 2-HIT hypothesis that the SGLT2i-induced stimulation of EGP, lipolysis, and ketone production requires the combination of volume depletion plus insulinopenia in T2D individuals.
Detailed Description:
After screening visit, subjects will participate in four additional visits and or at least one of the four visits that will be performed in random order starting at 6:00 AM to the Clinical Research Center at University Hospital-Texas Diabetes Institute.
Visit 2 (Study 1): At 6:00AM at (Study 1), a prime-continuous infusions of 6,6, D2-Glucose or U-3H-glucose and U-2H-glycerol or U-14C-Glycerol are started and continued to study end (2:00 PM) to measure rates of hepatic glucose production (HGP) and fat break down (lipolysis).3H-Glucose infusion to be given: (Prime=25µCi x (FPG/100), Continuous=0.25µCi/min x 480 min=120µCi). At time zero (9:00 AM) subjects will ingest Empagliflozin (25 mg). Plasma substrate, hormone concentrations, U-3H-glucose and U-14C-glycerol specific activities will be measured every 5-30 minutes for 300 minutes (2:00 PM) and 295 minutes. If Principal Investigator (PI) use U-2H-glycerol instead of U-14C Glycerol, PI will measure plasma U-2H-glycerol enrichment instead of U-14C-glycerol specific activities. Detailed explanation on page 54, if PI will use U-6,6, D2-Glucose instead of U-3H Glucose, PI will measure plasma 2H-Glucose enrichment instead of 3H Glucose specific activities. Detailed explanation on page 54.
Visit 3 (Study 2, Optional): At 6:00AM prime-continuous infusions of 6,6, D2-Glucose or U-3H-Glucose and U-2H-glycerol or U-14C-Glycerol are started and continued to study end (2:00 PM) to measure rates of hepatic glucose production (HGP) and lipolysis. 3H-Glucose infusion to be given: (Prime=25µCi x (FPG/100), Continuous=0.25µCi/min x 480 min=120µCi). At 7 AM an infusion of normal saline will be started at the rate of 150 ml/hour and continued to the end of study at 2 PM (total volume = 1050 ml; total Na and Cl = 154 meq) to provide volume replacement for blood loss. At time zero (9:00 AM) subjects will ingest Empagliflozin (25 mg). Plasma substrate, hormone concentrations, 3H-glucose and 14C-glycerol specific activities will be measured every 5-30 minutes for 300 minutes (2:00 PM) and 295 minute. If PI use U-2H-glycerol instead of U-14C Glycerol, PI will measure plasma U-2H-glycerol enrichment instead of U-14C-glycerol specific activities. Detailed explanation on page 55. If PI use U-6,6, D2-Glucose instead of U-3H Glucose, PI will measure plasma 2H-Glucose enrichment instead of 3H Glucose specific activities. Detailed explanation on page 55.
Visit 4 (Study 3, Optional): At 6:00AM prime-continuous infusions 6,6, D2-Glucose or U-3H-Glucose and U-2H-glycerol or U-14C-Glycerol are started and continued to study end (2:00 PM) to measure rates of Hepatic Glucose Production (HGP) and fat break down (lipolysis). 3H-Glucose infusion to be given: (Prime=25µCi x (FPG/100), Continuous=0.25µCi/min x 480 min=120µCi). At time zero (9:00 AM) subjects will ingest Empagliflozin (25 mg) and octreotide or somatostatin with insulin and glucagon will be given to reduce volume without insulinopenia. Plasma substrate and hormone concentrations and 3H-glucose/14C-glycerol specific activities will be measured every 5-30 minutes for 300 minutes (2:00 PM) and 295 minute. If PI use U-2H-glycerol instead of U-14C Glycerol, PI will measure plasma U-2H-glycerol enrichment instead of U-14C-glycerol specific activities. Detailed explanation on page 55-56. If PI uses U-6,6, D2-Glucose instead of U-3H Glucose, PI will measure plasma 2H-Glucose enrichment instead of 3H Glucose specific activities. Detailed explanation on page 56.
Visit 5 (Study 4, Optional): At 6:00AM prime-continuous infusions of 6,6, D2-Glucose or 3H-Glucose and U-2H-glycerol or U-14C-Glycerol are started and continued to study end (2:00 PM) to measure rates of hepatic (liver) glucose production (HGP) and fat break down (lipolysis). 3H-Glucose infusion to be given: (Prime=25µCi x (FPG/100), Continuous=0.25µCi/min x 480 min=120µCi). At 7 AM an infusion of normal saline will be started at the rate of 150 ml/hour and continued to the end of study at 2 PM (total volume = 1050 ml; total Na and Cl = 154 meq) to provide volume replacement for blood loss. At time zero (9:00 AM) subjects will ingest empagliflozin (25 mg) and octreotide or somatostatin with insulin and glucagon will be given. Plasma substrate and hormone concentrations and 3H-glucose/14C-glycerol specific activities will be measured every 5-30 minutes for 300 minutes (2:00 PM) and 295 minute. If PI uses U-2H-glycerol instead of U-14C Glycerol, PI will measure plasma U-2H-glycerol enrichment instead of U-14C-glycerol specific activities. Detailed explanation on page 56. If PI use U-6,6, D2-Glucose instead of U-3H Glucose, PI will measure plasma 2H-Glucose enrichment instead of 3H Glucose specific activities. Detailed explanation on page 56.
In Substudy II, PI will use stable isotopes (6,6-D2-glucose and U-2H-glycerol) or radioisotopes (U-3H-glucose and U-14C-glycerol) to measure endogenous glucose production (EGP) and fat breakdown (lipolysis), depending on isotope availability and cost. Both sets of isotopes will provide the necessary data to address research objectives.