| Outcome Measures: |
Primary: Change in Endogenous Glucose Production (EGP) After Acute Exposure to a Single Dose and Again After 16 Weeks of Treatment, After screening, eligible subjects will receive a measurement of endogenous glucose production (EGP) with a prime-continuous infusion of 3-3H-glucose. The EGP measurement will be performed in the morning after a 10-12 hour overnight fast and will last 8.5 hours (from 6 AM to 2:30 PM). After a 3.5-hour tracer equilibration period, subjects (20 per group) will receive one of the following medications: (i) placebo; (ii) exenatide 5 ug subcutaneously; (iii) dapagliflozin (10 mg); and (iv) dapagliflozin 10 mg + exenatide 5 ug \[ACUTE STUDY\]., ACUTE [after a single dose of each study drug or placebo]|Change in Endogenous Glucose Production (EGP) After 16 Weeks of Treatment With Each Study Drug., After screening, eligible subjects will receive a measurement of endogenous glucose production (EGP) with a prime-continuous infusion of 3-3H-glucose. The EGP measurement will be performed in the morning after a 10-12 hour overnight fast and will last 8.5 hours (from 6 AM to 2:30 PM). After a 3.5-hour tracer equilibration period, subjects (20 per group) will receive one of the following medications: (i) exenatide 5 ug subcutaneously; (ii) dapagliflozin (10 mg); and (iii) dapagliflozin 10 mg + exenatide 5 ug. Only three groups will be followed for 16 weeks since subjects are diabetic and placebo is not appropriate to use for this period. Again, subjects will be randomized to treatment with either exenatide, dapagliflozin or both drugs in combination. Repeat EGP will be measured again at 16 weeks as described above and data will be compared to respective "acute" studies., 16 weeks | Secondary: Change in Fasting Plasma Glucose (FPG) Concentration, The change in (FPG) above baseline following administration of study interventions after 16 weeks of treatment with each study drug(s) compared to data obtained during the acute exposure. Placebo arm was not included in this 16 week portion of the study, since subjects are diabetic. Only 3 arms of the study were conducted: (i) Byetta/Bydureon, (ii) Dapagliflozin (iii) Byetta/Bydureon plus Dapagliflozin., 16 weeks|Change in Plasma Glucagon Concentration, Measurement of change in plasma glucagon concentration after 16 weeks of treatment with each study drug(s) compared to acute exposure at baseline. Placebo arm was not included in this 16 week portion of the study, since subjects are diabetic. Only 3 arms of the study were conducted: (i) Byetta/Bydureon, (ii) Dapagliflozin (iii) Byetta/Bydureon plus Dapagliflozin., Baseline to 16 weeks|Change in Plasma Insulin Concentration, Measurement of change in plasma insulin concentration from baseline to 16 weeks following treatment with each study drug(s). Placebo arm was not included in this 16 week portion of the study, since subjects are diabetic. Only 3 arms of the study were conducted: (i) Byetta/Bydureon, (ii) Dapagliflozin (iii) Byetta/Bydureon plus Dapagliflozin., Baseline to 16 weeks
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