Combined exenatide and dapagliflozin has no additive effects on reduction of hepatocellular lipids despite better glycaemic control in patients with type 2 diabetes mellitus treated with metformin: EXENDA, a 24-week, prospective, randomized, placebo-controlled pilot trial

Aims: To investigate the potential synergistic effects of combined exenatide (EXE) and dapagliflozin (DAPA) versus (PLAC) placebo and DAPA on hepatocellular lipid (HCL) reduction after 24 weeks of treatment.

Materials and methods: Thirty patients with type 2 diabetes were randomized to weekly EXE and daily DAPA (n = 16) or weekly PLAC and daily DAPA (n = 14). Inclusion criteria were glycated haemoglobin (HbA1c) 48 to 97 mmol/mol (6.5-11%), age 18 to 75 years, body mass index (BMI) ≥25 kg/m² and metformin ≥1000 mg. The primary endpoint, HCL levels, were measured at baseline and after 24 weeks of treatment using magnetic resonance spectroscopy. Between-group effects were analysed using general linear models, adjusted for baseline outcome variables, age, sex and BMI. Within-group differences were assessed using a paired t-test.

Results: After 24 weeks, HCLs were reduced in both treatment groups (absolute change from baseline: EXE + DAPA -4.4%, 95% confidence interval [CI] -8.2, -0.7, P < 0.05; PLAC + DAPA -3.9%, 95% CI -6.0, -1.7, P < 0.01; relative change: EXE + DAPA -35.6%, PLAC + DAPA -32.3%) with no difference between groups. Similar findings were observed for subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT). HbA1c (EXE + DAPA -17.8 mmol/mol, [95% CI -24.8, -10.8], P <0.001; PLAC + DAPA -6.9 mmol/mol, [95% CI -10.5, -3.3], P = 0.001) and fasting glucose significantly decreased in both groups, although EXE + DAPA achieved better glycaemic control than PLAC + DAPA (adjusted difference: HbA1c -6.0 mmol/mol [95% CI -9.7, -2.2], P < 0.01). Body weight was reduced in both treatment groups (EXE + DAPA -7.3 kg, 95% CI -9.9, -4.8, P <0.001; PLAC + DAPA -4.6 kg, 95% CI -7.4, -1.8, P <0.01) with comparable results between groups. Changes in HCLs and weight, hip and waist circumference, VAT and SAT were positively associated.

Conclusion: After 24 weeks, HCLs were significantly but comparably reduced in the EXE + DAPA and PLAC + DAPA groups, despite significantly better glycaemic control in the combined group EXE + DAPA. Changes in HCLs were associated with weight loss and reduction of visceral adiposity, but not with glucose control. Further studies are necessary to evaluate possible additional long-term effects of a combined treatment.