Tirzepatide has demonstrated greater efficacy than semaglutide in improving glycemic control and reducing body weight in patients with type 2 diabetes mellitus (T2DM). However, the optimal tirzepatide dose following a switch from 1.0 mg of semaglutide remains unclear. This retrospective study included 15 T2DM patients who switched to tirzepatide due to inadequate weight loss. All patients started tirzepatide at 2.5 mg, with escalation to either 7.5 mg (n=10) or 10 mg (n=5). Changes in glycated hemoglobin (HbA1c) and body weight were assessed over a 3-month period. The 10 mg group experienced a significant reduction in HbA1c (-0.7%±0.3%, P<0.01) and a non-significant trend toward weight loss (-6.6±5.4 kg, P=0.07). In contrast, no significant changes were observed in the 7.5 mg group. There were no statistically significant differences between groups. Since 10 mg of tirzepatide significantly improved glycemic control after switching from 1.0 mg of semaglutide, early escalation to 10 mg may be beneficial for patients who respond inadequately to semaglutide.