Use of Premixed Insulin, Metformin, and a Glucagon-Like Peptide 1 Receptor Agonist as a Therapeutic Approach for Uncontrolled Type 2 Diabetes

OBJECTIVE | To explore the use of premixed insulin, a glucagon-like peptide 1 (GLP-1) receptor agonist, and metformin as combination therapy for type 2 diabetes. DESIGN AND METHODS | All adult patients with type 2 diabetes who had been prescribed premixed insulin and a GLP-1 receptor agonist simultaneously at our outpatient clinic were selected for retrospective review. We reviewed A1C, weight, cumulative daily insulin dose, and adverse events over 12 months. RESULTS | A total of 72 patients received premixed insulin and a GLP-1 receptor agonist, of which 32 met inclusion criteria. The average duration of type 2 diabetes for these patients was 14.2 ± 7.1 years. Mean A1C at baseline was 10.5 ± 2.1%. At 12 months, mean A1C was 8.3 ± 1.9%. The change in mean A1C after 12 months was -2.2% (95% CI -3.433 to -1.014, P <0.0001). At 12 months, the mean cumulative insulin dose was 33.3 units less than before the therapy change (95% CI -57.13 to -9.46, P = 0.0030). Average weight change at 12 months was -2.2 kg (95% CI -27.6 to 37.6, P = NS). After 12 months, 61% of included patients (19 of 31) had an A1C ≤8%. Six additional patients were not included in analysis because they stopped the regimen after <3 months because of adverse events. CONCLUSION | Despite a decreased cumulative daily dose of insulin, patients with historically uncontrolled type 2 diabetes using metformin, premixed insulin, and a GLP-1 receptor agonist in combination experienced improved glycemic control over 12 months. Prospective randomized trials are needed to better assess the potential benefit of this combination therapy.