Comparative effectiveness of early versus delayed metformin in the treatment of type 2 diabetes.

AIM: The purpose of this study was to evaluate the effectiveness of early versus delayed initiation of metformin in type 2 diabetes.

METHODS: We identified 2925 new users of metformin with type 2 diabetes between 2005 and 2012 in the electronic health records of an integrated health system in Northern California. Patients were matched 1:1 on the propensity for receiving early treatment (defined as ≤6 months from first evidence of diabetes). We evaluated the effectiveness of early versus delayed metformin treatment on intermediate clinical outcomes indicated by changes in hemoglobin A1c (HbA1c) and body mass index (BMI), as well as the incidence of therapy intensification (addition or substitution of a second antihyperglycemic agent).

RESULTS: A total of 2144 propensity-score matched patients were included in the early or delayed treatment group (n=1072, in each). Early treatment was associated with significantly larger decreases in HbA1c (-0.36%; 95% confidence intervals [CI]: -0.44 to -0.27%; P<0.001) and BMI (-0.46kg/m2; 95% CI: -0.64 to -0.29kg/m2; P<0.001) relative to delayed treatment. Patients receiving early treatment also had a greater likelihood of attaining an HbA1c<7% (<53mmol/mol) (odds ratio: 2.00; 95% CI: 1.63-2.45; P<0.001) and a reduced risk of therapy intensification (hazard ratio: 0.72; 95% CI: 0.61-0.85; P<0.001).

CONCLUSIONS: Treatment with metformin earlier in the course of type 2 diabetes is associated with better glycemic control, more pronounced weight reduction, and a lower risk for therapy intensification than delayed treatment. Antihyperglycemic therapy should be initiated early after diagnosis to achieve optimal outcomes.