Efficacy and safety of insulin glargine added to a fixed-dose combination of metformin and a dipeptidyl peptidase-4 inhibitor: results of the GOLD observational study

Abstract

Background: For patients with type 2 diabetes who are uncontrolled on a combination of two oral antidiabetic agents, addition of the long-acting basal insulin glargine is a well established treatment option. However, data on the efficacy and safety of a combination of metformin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, and insulin glargine are limited in real-world settings. Therefore, the aim of this study was to analyze blood glucose control, rates of hypoglycemia and body weight in a large cohort of patients with type 2 diabetes treated with this combination therapy in real practice.

Methods: This noninterventional, multicenter, prospective, observational trial with a follow-up of 20 weeks enrolled insulin-naïve patients who had been on a stable fixed dose of metformin and a DPP-4 inhibitor for at least 3 months, and had a glycosylated hemoglobin (HbA1c) between 7.5% and 10%. Patients were selected at the investigators' discretion for initiation of insulin glargine at baseline. A total of 1,483 patients were included, of whom 1,262 were considered to be the efficacy set. Primary efficacy parameters were HbA1c and fasting plasma glucose. Secondary outcome measures included achievement of glycemic targets, body weight, rates of hypoglycemia, and other safety parameters, as well as resource consumption.

Results: Upon initiation of insulin glargine, mean HbA1c decreased from 8.51% to 7.36% (-1.15%±0.91%; 95% confidence interval [CI] -1.20 to -1.10). An HbA1c level<6.5% was achieved in 8.2% of patients and a level<7.0% in 31.5%. Mean fasting plasma glucose decreased from 174±47 mg/dL to 127±31 mg/dL (-47.3±44.1 mg/dL; 95% CI -49.8 to -44.8). In 11.9% of patients, a fasting plasma glucose level<100 mg/dL was achieved. Bodyweight decreased on average by 0.98±3.90 kg (95% CI 1.19-0.76). Hypoglycemia (blood glucose≤70 mg/dL) was observed in 29 patients (2.30%), of whom six (0.48%) had nocturnal hypoglycemia and four (0.32%) had documented severe events (blood glucose<56 mg/dL).

Conclusion: The results of this observational study show that insulin glargine, when added to a fixed-dose combination of metformin and a DPP-4 inhibitor, resulted in a significant and clinically relevant improvement of glycemic control. Importantly, this intervention did not interfere with the action of the DPP-4 inhibitors, resulting in neutral effects on weight and low rates of hypoglycemia. We conclude that this treatment intensification approach may be useful, efficient, and safe in daily clinical practice for patients with type 2 diabetes.

Keywords: diabetes; dipeptidyl dipeptidase-4 inhibitors; insulin glargine; metformin.