Combining a glucagon-like peptide-1 receptor agonist (GLP1-RA) with basal insulin is an emerging option when initiating injectable therapy in longstanding type 2 diabetes (T2DM). Recognizing that short-term insulin therapy can improve beta-cell function and induce glycemic remission in early T2DM, we hypothesized that adding the short-acting GLP1-RA exenatide to basal insulin in early T2DM may enhance the achievability of these outcomes. In this completed, 20-week, open-label, parallel-arm trial at an academic hospital, 103 individuals aged 30-80 years with <7 years duration of T2DM were randomized (by computer-generated sequence) to 8-weeks treatment with (i) insulin glargine (Glar; n = 33), (ii) glargine + thrice-daily lispro (Glar/Lispro; n = 35), or (iii) glargine + twice-daily exenatide (Glar/Exenatide; n = 35), followed by 12-weeks washout. The analyzed population of 102 participants (median 3.5 years of T2DM, A1c 6.6% ±0.7%) consisted of 33 on Glar, 35 on Glar/Lispro and 34 on Glar/Exenatide. Oral glucose tolerance tests at baseline, 4-weeks, 8-weeks and 20-weeks enabled assessment of beta-cell function (Insulin Secretion-Sensitivity Index-2 (ISSI-2)) and glycemic control. Mean ISSI-2 over the 8-week intervention (primary outcome) did not differ across the groups (Glar/Exenatide 237 ± 11; Glar/Lispro 208 ± 11; Glar 223 ± 11; p = 0.19). Baseline-adjusted A1c at 8-weeks (secondary outcome) was lowest in Glar/Exenatide followed by Glar/Lispro and Glar (mean 5.9% vs 6.0% vs 6.2%; p = 0.0007). After 12-weeks washout, however, neither baseline-adjusted A1c nor baseline-adjusted ISSI-2 (secondary outcomes) differed between the groups, nor did (additional outcome) rates of remission (Glar/Exenatide 26.7%, Glar/Lispro 43.8%, Glar 32.1%; p = 0.35). There were no severe hypoglycemia episodes. In conclusion, adding exenatide to basal insulin in early T2DM does not further enhance underlying beta-cell function or the capacity to achieve diabetes remission, despite yielding on-treatment glycemic benefit.
