Objective: Combined treatment with an incretin-based drug, such as a glucagon-like peptide 1 receptor agonist (GLP-1 RA) or a dipeptidyl peptidase-4 (DPP-4) inhibitor, and basal insulin is a new strategy for improving glucose control in type 1 diabetes mellitus (T1DM). We performed a meta-analysis to assess the effect of this combined treatment on glycaemic control, insulin dose, severe hypoglycaemia, weight gain, and gastrointestinal side effects in T1DM patients.
Methods: We searched PubMed, EMBASE and the Cochrane Library for relevant studies published before July 16, 2018. The primary outcome was glycosylated haemoglobin (HbA1c). Secondary outcomes included total daily insulin dose, body weight, severe hypoglycaemia and gastrointestinal side effects.
Results: Nine randomized controlled trials (RCTs) involving 2389 patients were ultimately included in the meta-analysis. The pooled data suggested that incretin-based therapy was associated with a reduction in HbA1c levels [weighted mean difference (WMD) -0.17%, 95% confidence interval (CI) -0.24 to -0.11, P<0.001)], total daily insulin dose (WMD -5.53 IU/day, 95% CI -8.89 to -2.17, P=0.001) and body weight (WMD -3.24 kg, 95% CI -4.43 to -2.04, P<0.001). Incretins did not increase the risk of severe hypoglycaemia [odds ratio (OR) 0.83, 95% CI 0.60 to 1.16, P=0.287] but increased the occurrence of gastrointestinal side effects (OR 3.46, 95% CI 2.20 to 5.45 P<0.001).
Conclusions: In T1DM patients, GLP-1 RAs, but not DPP-4 inhibitors, combined with insulin appear to be an effective therapy but may increase the occurrence of gastrointestinal side effects.