OBJECTIVE To compare the effects of the neutral protamine Hagedorn (NPH) recombinant human insulin formulations Gansulin and Humulin N® on the glycemic control of patients with type 2 diabetes mellitus (T2DM). METHODS Prospective, double-blind, randomized, parallel, single-center study of 37 individuals with T2DM treated with NPH insulin formulations. The Tukey-Kramer test for multiple comparisons, the Wilcoxon paired comparison test and the Chi-Square test were used for the statistical analyses. The significance level was set at 5% (p < 0.05). RESULTS The NPH insulin formulations Humulin and Gansulin similarly reduced the HbA1c levels observed at the end of the study compared with the values obtained at the beginning of the study. In the Humulin group, the initial HbA1c value of 7.91% was reduced to 6.56% (p < 0.001), whereas in the Gansulin group, the reduction was from 8.18% to 6.65% (p < 0.001). At the end of the study, there was no significant difference between the levels of glycated hemoglobin (p = 0.2410), fasting plasma glucose (FG; p = 0.9257) and bedtime plasma glucose (BG; p = 0.3906) between the two insulin formulations. There was no nt difference in the number of hypoglycemic events between the two insulin formulations, and no severe hyp episodes were recorded. CONCLUSIONS This study demonstrated similar glycemic control by NPH insulin Gansulin compared with human insulin Humulin N® in patients with T2DM.