Effectiveness and safety of glucose-lowering drugs as an adjunct to insulin therapy in Chinese patients with type 1 diabetes: a retrospective, observational study

Aim To assess the real-world impact of glucose-lowering drugs (GLDs) as an adjunct to insulin in Chinese patients with type 1 diabetes (T1DM). Methods This dual-center, observational, retrospective study included 121 T1DM patients receiving GLDs as adjuncts and 56 participants with insulin-only drugs as comparators. Glycated hemoglobin A1c (HbA1c), daily insulin dosage, fasting blood glucose (FBG), postprandial blood glucose (PBG), nocturnal blood glucose (NBG) and the difference in trough and peak blood glucose levels on the same day (Delta TP) were assessed at baseline and at the end of the study. Results In total, HbA1c decreased by 1.14% in the GLD+insulin group (p < 0.0001) and 0.36% in the insulin-only group (p = 0.0423, mean adjusted difference, -0.09% [95% CI, -0.55 to 0.37]). The total daily insulin concentration was reduced by 7.34 U per day in the GLD+insulin group vs. 5.55 U per day in the insulin-only group (mean adjusted difference, -2.32 U [95% CI, -4.97 to 0.33]). In particular, among patients with fasting C-peptide levels < 17 pmol/L, the total daily insulin concentration was significantly reduced by 9.22 U vs. 5.09 U per day (mean adjusted difference, -3.84 [95% CI, -6.85-0.84]; p = 0.0129). There were no notable differences in the other glycemic indices between the two groups. A gradual downward trend in changes in glycemic outcomes was observed among patients treated with various combinations of metformin, acarbose, and dipeptidyl peptidase 4 inhibitor (DPP-4i). Similar reductions in the daily insulin dose were also detected in most of the GLD+insulin group in addition to the DPP-4i-only group. No severe hypoglycemia was induced by additional GLDs. Conclusions The use of additional GLDs tends to improve glycemic outcomes and reduce insulin requirements in patients with T1DM. These results indicate that the use of GLDs as an adjunctive therapy may have been an effective treatment strategy among adults with T1DM in China.