Meta-analysis of seven heterogeneous studies on liraglutide add-on therapy in patients with type 2 diabetes mellitus treated with insulin.

BACKGROUND AND AIMS: Clinical trials indicate the efficacy of add-on therapy using incretin-related drugs to treat type 2 diabetes mellitus (DM) inadequately controlled by insulin. However, heterogeneity exists among these studies. Baseline body mass index (BMI) accounts for the heterogeneity of add-on therapy with dipeptidyl peptidase-4 (DPP-4) inhibitors and the associated higher BMI with a lower efficacy. The efficacy of add-on therapy with glucagon-like peptide-1 (GLP-1) receptor agonists remains unclear. METHODS: We performed a meta-analysis of randomized controlled trials of ≥12 weeks reporting the endpoint of adjusted mean change in hemoglobin A1c levels (AMΔHbA1c) or hypoglycemia incidence. Patients with type 2 DM treated with insulin alone or with metformin for at least 8 weeks before the study treatment were included. The intervention group received liraglutide co-administered with insulin or a fixed-dose combination. The control group received a placebo or insulin. Covariates included five baseline parameters (HbA1c, fasting plasma glucose, BMI, type 2 DM duration, and treatment duration). RESULTS: Seven studies (2067 patients) were selected. AMΔHbA1c was -1.00% (95% confidence interval [CI]: -1.21 to -0.78, I2 = 74.7%). The odds ratio for hypoglycemia incidence was 0.97 (95% CI: 0.50-1.87, I2 = 81.9%). Covariates did not account for the heterogeneity in AMΔHbA1c or hypoglycemia incidence. CONCLUSIONS: Liraglutide add-on therapy reduced HbA1c levels without increasing hypoglycemia incidence, independent of BMI, in insulin non-responders with type 2 DM. GLP-1 receptor agonists may be more suitable than DPP-4 inhibitors for add-on therapy in patients with high BMI. REGISTRATION NUMBER: PROSPERO #CRD42021178888.

Meta-Analysis of 11 Heterogeneous Studies regarding Dipeptidyl Peptidase 4 Inhibitor Add-On Therapy for Type 2 Diabetes Mellitus Patients Treated with Insulin.

BACKGROUND: Several clinical trials have addressed the therapeutic strategy of adding dipeptidyl peptidase 4 (DPP-4) inhibitors to the treatment of type 2 diabetes mellitus (DM) inadequately controlled by insulin therapy. However, there is a high degree of heterogeneity in these studies, and the cause of which has not been identified. METHODS: We conducted a meta-analysis of randomized controlled trials, which compared the efficacy and safety of adding DPP-4 inhibitors or placebo to insulin therapy; the level of hemoglobin A1c (HbA1c) in the patients was >7.0%, and the duration of treatment was ≥8 weeks. We focused on the mean changes in HbA1c from the baseline (ΔHbA1c) and the incidence of hypoglycemia. We assumed that five baseline parameters (HbA1c, fasting blood glucose, body mass index (BMI), duration of type 2 DM, and duration of treatment) could affect ΔHbA1c. Regarding the incidence of hypoglycemia, we suspected that the heterogeneity was caused by differences in the definition of hypoglycemia among the studies. RESULTS: Data obtained from 11 studies (n = 4654 patients) were included in the analysis. The mean ΔHbA1c between the DPP-4 inhibitor and placebo groups was -0.61% (95% confidence interval (CI): -0.74 to -0.48, I 2 = 73.4%). There was substantial heterogeneity among the 11 studies, but 74.1% of this variability was explained by the difference in BMI. The odds ratio for the incidence of hypoglycemia was 1.02 (95% CI: 0.74 to 1.42, I 2 = 63.8%), with substantial heterogeneity due to differences in the definition of hypoglycemia among the studies. There was no apparent effect of publication bias. CONCLUSIONS: The addition of DPP-4 inhibitors to insulin therapy for adult patients with type 2 DM can significantly reduce HbA1c levels without increasing the occurrence of hypoglycemia. BMI and hypoglycemia definition could explain the heterogeneity in the clinical trials. This trial is registered with PROSPERO #CRD42016035994.