Objective: This study was aimed to assess comparative effectiveness of basal insulin vs. oral antidiabetic drugs (OADs) as 2nd-line added-on treatment to metformin monotherapy on macro- and microvascular complications, hypoglycemic events, and all-cause mortality in patients with type 2 diabetes (T2DM).

Methods: A population-based cohort study was conducted using Taiwan’s National Health Insurance Research Database. Study population was newly-diagnosed with T2DM in 1999-2011, and the new and stable users of basal insulin or OADs (i.e., sulphonylurea [SU], dipeptidyl peptidase-4 inhibitor [DPP-4i]) as 2nd-line add-on treatment to metformin during 2009-2011, and followed until death or the end of 2013. Propensity score matching was applied to achieve comparability in patient baseline characteristics at the time of 2nd-line treatment initiation between basal insulin and OAD users. Cox models were used to evaluate risks of study outcomes associated with use of basal insulin vs. OADs.

Result: Our analyses included 1,064 and 951 basal insulin users 1:1 matched with SU and DPP-4i users, respectively. Compared to SU, use of basal insulin was associated with significantly higher risks of macrovascular events (hazard ratio: 1.36 [95% confidence interval: 1.08-1.71]), microvascular events (1.25 [1.21-1.40]), hypoglycemia (1.88 [1.44-2.46]), and all-cause death (1.50 [1.03-2.20]). Compared to DPP-4i, use of basal insulin yielded a greater risk increase in macrovascular events (1.52 [1.18-1.97]), microvascular events (1.43 [1.27-1.61]), hypoglycemia (3.28 [2.33-4.64]), and all-cause death (2.58 [1.59-4.19]).

Conclusion: T2DM patients who initiated basal insulin vs. SU or DPP-4i as 2nd-line added-on treatment to metformin had higher risks of vascular complications, hypoglycemia, and all-cause death.


P. Chen: None. S. Kuo: None. H. Ou: None.


National Institute of Diabetes and Digestive and Kidney Diseases (P30DK092926)

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