To compare the efficacy and safety of insulin glargine vs additional oral antidiabetic drug (OAD) combined with one basic OAD in patients with poorly controlled type 2 diabetes mellitus (T2DM).

A total of 387 patients (mean age 54 years) with T2DM who were inadequately controlled with one kind of sulfonylureas (SU) or metformin for at least 3 months were eligible for enrollment from 12 centres of China from June 2006 to December 2007. All the patients were randomized to receive insulin glargine (Group A, n=193) or an additional OAD (Group B, n=194) for 24 weeks. The changes in glycated haemoglobin (HbA1c) level, blood glucose parameters, and C-peptide level and incidence of hypoglycemia were assessed and compared between the two groups at 24 weeks. Student's t test was used for data analysis.

A total of 375 patients were included in the final analysis (186 in Group A and 189 in Group B). After 24-week treatment, the reduction of HbA1c from baseline was 1.5% in Group A and 1.3% in Group B (t=-7802.0, -6983.5, both P<0.01), and the reduction was comparable between the two groups (Z=-1.3914, P=0.1641). The reduction of HbA1c from baseline to 24 weeks in the subgroup of insulin glargine≥0.2 U·kg^-1·d^-1 (n=114) was significantly larger than that of Group B ((1.6±1.2)% vs (1.3±1.3)%, Z=-1.9962, P=0.0459). The reduction of fasting plasma glucose (FPG) and 2-h plasma glucose (2-h PG) from baseline to 24 weeks in Group A was significantly larger than that in Group B (Z=-5.5516, -3.9158, both P<0.01). The changes of 0 or 2-h C-peptide level from baseline to 24 weeks were significantly different between the two groups(Z=-5.3894, -2.7775, both P<0.01). The incidence of hypoglycemia was comparable between the two groups.

These findings show that additional treatment with insulin glargine or another OAD could contribute to effective control of blood glucose, and insulin glargine may boast stronger effectiveness when the dosage is titrated sufficiently.

Diabetes mellitus, type 2; Insulin; Hypoglycemic agents