Which is better, high-dose metformin monotherapy or low-dose metformin/linagliptin combination therapy, in improving glycemic variability in type 2 diabetes patients with insufficient glycemic control despite low-dose metformin monotherapy? A randomized, cross-over, continuous glucose monitoring-based pilot study.

Aims/introduction: The present study investigated the effect of high-dose metformin or low-dose metformin/linagliptin combination therapy on glycemic variability (GV) in type 2 diabetes patients with insufficient glycemic control despite low-dose metformin monotherapy in a cross-over study using continuous glucose monitoring.

Materials And Methods: The present study was carried out with 11 type 2 diabetes outpatients (7% < glycated hemoglobin < 10%) receiving low-dose metformin monotherapy (500-1,000 mg). All patients were assigned to either metformin 1,500 mg monotherapy (HMET) or combination therapy of low-dose (750 mg) metformin and linagliptin 5 mg (LMET + dipeptidyl peptidase-4 [DPP4]). GV was evaluated by continuous glucose monitoring after >4 weeks of the initial treatment and again after cross-over to the other treatment. GV metrics were compared between the treatments using the Wilcoxon signed-rank test.

Results: Of the continuous glucose monitoring-derived GV metrics for the HMET versus LMET + DPP4, mean glucose levels, standard deviations and mean amplitude of glucose excursions were not significantly different. Although the pre-breakfast glucose levels were not significantly different among the treatments (P = 0.248), the 3-h postprandial glucose area under the curve (>160 mg/dL) after breakfast was significantly larger with HMET versus LMET + DPP4 (9,550 [2,075-11,395] vs 4,065 [1,950-8,895]; P = 0.041).

Conclusions: A comparison of GV with HMET versus LMET + DPP4 suggested that LMET + DPP4 might reduce post-breakfast GV to a greater degree than HMET in type 2 diabetes patients receiving low-dose metformin monotherapy.