Abstract To evaluate the effect of medical nutritional therapy (MNT) combined with low glycaemic index (LGI) formula at breakfast for 4 weeks on the glycaemic control of patients with type 2 diabetes mellitus (T2DM). Ninety-six participants were recruited and randomly equally divided into two groups. The intervention group was offered with 40g LGI formula at breakfast adjusted according to MNT, and the control group with regular MNT. After 4 weeks, fasting blood glucose, glycated albumin (GA), insulin, C-peptide levels and metabolic index were compared between the two groups. Compared to the intervention group, the total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and the change of FBG (–0.64 ± 1.4 vs. 0.3 ± 2.2; p < 0.05) and 2h-PBG (–1.8 ± 3.6 vs.0.8 ± 3.2; p < 0.01) in the control group were significantly decreased. The LGI formulations, having a significant effect on controlling glucose and lipid metabolism, could be used as a non-pharmacological intervention for T2DM self-management.