OBJECTIVE To examine the effect of combination therapy with canagliflozin plus liraglutide on HbA 1c , endogenous glucose production (EGP), and body weight versus each therapy alone. RESEARCH DESIGN AND METHODS Forty-five patients with poorly controlled (HbA 1c 7–11%) type 2 diabetes mellitus (T2DM) on metformin with or without sulfonylurea received a 9-h measurement of EGP with [3- 3 H]glucose infusion, after which they were randomized to receive 1 ) liraglutide 1.2 mg/day (LIRA), 2 ) canagliflozin 100 mg/day (CANA), or 3 ) liraglutide 1.2 mg plus canagliflozin 100 mg (CANA/LIRA) for 16 weeks. At 16 weeks, the EGP measurement was repeated. RESULTS The mean decrease from baseline to 16 weeks in HbA 1c was −1.67 ± 0.29% ( P = 0.0001), −0.89 ± 0.24% ( P = 0.002), and −1.44 ± 0.39% ( P = 0.004) in patients receiving CANA/LIRA, CANA, and LIRA, respectively. The decrease in body weight was −6.0 ± 0.8 kg ( P < 0.0001), −3.5 ± 0.5 kg ( P < 0.0001), and −1.9 ± 0.8 kg ( P = 0.03), respectively. CANA monotherapy caused a 9% increase in basal rate of EGP ( P < 0.05), which was accompanied by a 50% increase ( P < 0.05) in plasma glucagon-to-insulin ratio. LIRA monotherapy reduced plasma glucagon concentration and inhibited EGP. In CANA/LIRA-treated patients, EGP increased by 15% ( P < 0.05), even though the plasma insulin response was maintained at baseline and the CANA-induced rise in plasma glucagon concentration was blocked. CONCLUSIONS These results demonstrate that liraglutide failed to block the increase in EGP caused by canagliflozin despite blocking the rise in plasma glucagon and preventing the decrease in plasma insulin concentration caused by canagliflozin. The failure of liraglutide to prevent the increase in EGP caused by canagliflozin explains the lack of additive effect of these two agents on HbA 1c .

The decrement in plasma glucose concentration with SGLT2 inhibitors (SGLT2i) is blunted by a rise in endogenous glucose production (EGP). We investigated the ability of incretin treatment to offset the EGP increase. Subjects with type 2 diabetes ( = 36) were randomized to ) canagliflozin (CANA),) liraglutide (LIRA), or ) CANA plus LIRA (CANA/LIRA). EGP was measured with [3-H]glucose with or without drugs for 360 min. In the pretreatment studies, EGP was comparable and decreased (2.2 ± 0.1 to 1.7 ± 0.2 mg/kg ⋅ min) during a 300- to 360-min period ( < 0.01). The decrement in EGP was attenuated with CANA (2.1 ± 0.1 to 1.9 ± 0.1 mg/kg ⋅ min) and CANA/LIRA (2.2 ± 0.1 to 2.0 ± 0.1 mg/kg ⋅ min), whereas with LIRA it was the same (2.4 ± 0.2 to 1.8 ± 0.2 mg/kg ⋅ min) (all < 0.05 vs. baseline). After CANA, the fasting plasma insulin concentration decreased (18 ± 2 to 12 ± 2 μU/mL, < 0.05), while it remained unchanged in LIRA (18 ± 2 vs. 16 ± 2 μU/mL) and CANA/LIRA (17 ± 1 vs. 15 ± 2 μU/mL). Mean plasma glucagon did not change during the pretreatment studies from 0 to 360 min, while it increased with CANA (69 ± 3 to 78 ± 2 pg/mL, < 0.05), decreased with LIRA (93 ± 6 to 80 ± 6 pg/mL, < 0.05), and did not change in CANA/LIRA. LIRA prevented the insulin decline and blocked the glucagon rise observed with CANA but did not inhibit the increase in EGP. Factors other than insulin and glucagon contribute to the stimulation of EGP after CANA-induced glucosuria.

Sodium-glucose cotransport 2 inhibitors (SGLT2i) lower plasma glucose but stimulate endogenous glucose production (EGP). The current study examined the effect of dapagliflozin on EGP while clamping plasma glucose, insulin, and glucagon concentrations at their fasting level. Thirty-eight patients with type 2 diabetes received an 8-h measurement of EGP ([3-3 H]-glucose) on three occasions. After a 3-h tracer equilibration, subjects received 1) dapagliflozin 10 mg (n 5 26) or placebo (n 5 12); 2) repeat EGP measurement with the plasma glucose concentration clamped at the fasting level; and 3) repeat EGP measurement with inhibition of insulin and glucagon secretion with somatostatin infusion and replacement of basal plasma insulin and glucagon concentrations. In study 1, the change in EGP (baseline to last hour of EGP measurement) in subjects receiving dapagliflozin was 22% greater (10.66 6 0.11 mg/kg/min, P < 0.05) than in subjects receiving placebo, and it was associated with a significant increase in plasma glucagon and a decrease in the plasma insulin concentration compared with placebo. Under glucose clamp conditions (study 2), the change in plasma insulin and glucagon concentrations was comparable in subjects receiving dapagliflozin and placebo, yet the difference in EGP between dapagliflozin and placebo persisted (10.71 6 0.13 mg/kg/min, P < 0.01). Under pancreatic clamp conditions (study 3), dapagliflozin produced an initial large decrease in EGP (8% below placebo), followed by a progressive increase in EGP that was 10.6% greater than placebo during the last hour. Collectively, these results indicate that 1) the changes in plasma insulin and glucagon concentration after SGLT2i administration are secondary to the decrease in plasma glucose concentration, and 2) the dapagliflozin-induced increase in EGP cannot be explained by the increase in plasma glucagon or decrease in plasma insulin or glucose concentrations.

Mitochondrial function has been examined in insulin-resistant (IR) states including type 2 diabetes mellitus (T2DM). Previous studies using phosphorus-31 magnetic resonance spectroscopy (P-MRS) in T2DM reported results as relative concentrations of metabolite ratios, which could obscure differences in phosphocreatine ([PCr]) and adenosine triphosphate concentrations ([ATP]) between T2DM and normal glucose tolerance (NGT) individuals. We used an image-guided P-MRS method to quantitate [PCr], inorganic phosphate [Pi], phosphodiester [PDE], and [ATP] in vastus lateralis (VL) muscle in 11 T2DM and 14 NGT subjects. Subjects also received oral glucose tolerance test, euglycemic insulin clamp, H-MRS to measure intramyocellular lipids [IMCL], and VL muscle biopsy to evaluate mitochondrial density. T2DM subjects had lower absolute [PCr] and [ATP] than NGT subjects (PCr 28.6 ± 3.2 vs. 24.6 ± 2.4, P< 0.002, and ATP 7.18 ± 0.6 vs. 6.37 ± 1.1, P < 0.02) while [PDE] was higher, but not significantly. [PCr], obtained using the traditional ratio method, showed no significant difference between groups. [PCr] was negatively correlated with HbA1c ( r = -0.63, P < 0.01) and fasting plasma glucose ( r = -0.51, P = 0.01). [PDE] was negatively correlated with Matsuda index ( r = -0.43, P = 0.03) and M/I ( r = -0.46, P = 0.04), but was positively correlated with [IMCL] ( r = 0.64, P < 0.005), HbA1c, and FPG ( r = 0.60, P = 0.001). To summarize, using a modified, in vivo quantitative P-MRS method, skeletal muscle [PCr] and [ATP] are reduced in T2DM, while this difference was not observed with the traditional ratio method. The strong inverse correlation between [PCr] vs. HbA1c, FPG, and insulin sensitivity supports the concept that lower baseline skeletal muscle [PCr] is related to key determinants of glucose homeostasis.