The vascular function effects of adding exenatide or meal insulin to basal insulin therapy in early type 2 diabetes

Objective Basal insulin glargine has a neutral effect on cardiovascular risk in type 2 diabetes (T2DM). In practice, basal insulin is often paired with a glucagon-like peptide-1 receptor agonist (GLP1-RA) or meal insulin; however, the cardiovascular implications of these combinations have not been fully elucidated. In this context, we sought to evaluate the vascular function effects of adding the GLP1-RA exenatide or meal insulin lispro to basal glargine therapy in early T2DM. Methods In this 20-week trial, adults with T2DM of < 7-years duration were randomized to 8-weeks treatment with (i) insulin glargine (Glar), (ii) glargine + thrice-daily lispro (Glar/Lispro), or (iii) glargine + twice-daily exenatide (Glar/Exenatide), followed by 12-weeks washout. At baseline, 8-weeks, and washout, fasting endothelial function was assessed with reactive hyperemia index (RHI) measurement by peripheral arterial tonometry. Results At baseline, there were no differences in blood pressure (BP), heart rate (HR) or RHI between participants randomized to Glar (n = 24), Glar/Lispro (n = 24), and Glar/Exenatide (n = 25). At 8-weeks, Glar/Exenatide decreased systolic BP (mean − 8.1 mmHg [95%CI − 13.9 to − 2.4], p = 0.008) and diastolic BP (mean − 5.1 mmHg [− 9.0 to − 1.3], p = 0.012) compared to baseline, with no significant changes in HR or RHI. Notably, baseline-adjusted RHI (mean ± SE) did not differ between the groups at 8-weeks (Glar 2.07 ± 0.10; Glar/Lispro 2.00 ± 0.10; Glar/Exenatide 1.81 ± 0.10; p = 0.19), nor did baseline-adjusted BP or HR. There were no differences between the groups in baseline-adjusted RHI, BP or HR after 12-weeks washout. Conclusion Adding either exenatide or lispro to basal insulin therapy does not appear to affect fasting endothelial function in early T2DM. Trial Registration: ClinicalTrials.Gov NCT02194595.