Tirzepatide added to basal insulin showed marked improvements in glycemic control in adults with uncontrolled type 2 diabetes. The findings, published in The Lancet: Diabetes & Endocrinology, come from the SURPASS-CN-INS trial, a 40-week, double-blind, multicentre, randomized, placebo-controlled study conducted across 26 hospitals in China.

The trial enrolled 257 adults, of whom 255 were included in the efficacy analysis. Participants received tirzepatide 5 mg, 10 mg, or 15 mg, or placebo, while continuing once-daily insulin glargine with or without metformin or a sodium–glucose cotransporter-2 (SGLT2) inhibitor.

Tirzepatide led to significantly greater HbA1c reductions at week 40. HbA1c decreased by 2.39% in the 10 mg group and 2.37% in the 15 mg group, compared with a 0.91% reduction with placebo. Differences versus placebo were –1.48% and –1.45%, respectively (p<0.0001 for both doses).

Gastrointestinal events such as diarrhoea, decreased appetite, nausea, and vomiting were more common with tirzepatide but were generally mild to moderate. Upper respiratory tract infections occurred at similar rates across all groups.

These results show that tirzepatide, when added to basal insulin, provides strong glycemic efficacy with an acceptable safety profile, supporting its therapeutic use in adults with type 2 diabetes in China.