Inadequate glycemic control in patients with current premixed insulin regimens is often due to the short half-life and pronounced peak-to-trough ratio of basal insulin. This study evaluated insulin GZR33 (GZR33), an ultra-long basal insulin, and insulin GZR101 (GZR101), which is a premix of GZR33 and postprandial insulin aspart. The binding affinity of GZR33 to the human insulin receptor (hIR) was analyzed using surface plasmon resonance. Potency was tested in vivo in streptozotocin-induced T1DM rats and db/db T2DM mice, using insulin degludec (degludec, IDeg) and insulin degludec/insulin aspart (IDegAsp) as controls. GZR33 was constructed by linking a C22 fatty diacid side chain to desB30 human insulin via a 6 × oligoethylene glycol (OEG) linker. GZR33 exhibited strong hIR-A and hIR-B binding (dissociation constants: 2.86E-6 M and 1.28E-6 M). It activated IRA and IRB with EC50 of 370.13 ± 94.86 nM and 477.48 ± 64.28 nM, respectively, in 0.5% human serum albumin (HSA), and induced adipogenesis with an EC50 of 2.45 ± 0.81 nM. GZR33 demonstrated a half-life twice as long as degludec (5.45 h vs 2.22 h in SD rats) and superior binding affinity to HSA (80-fold higher). In T1DM rats and T2DM mice, GZR33 outperformed IDeg in reducing HbA1c and improving glucose tolerance, demonstrating a potency at least three-fold higher than IDeg at the same molar concentration. GZR101 showed proportional glucose-lowering effects, combining the long-acting profile of GZR33 with the rapid action of insulin aspart. Therefore, GZR101 provides a promising once-daily premixed insulin candidate with potential to enhance glycemic control and patient adherence. Clinical trial number: not applicable.