JMIR Publications

ABSTRACT

Background:

Gestational diabetes (GDM) is one of the most common complications in pregnancy. Optimal glycemic control is key to reduce the risk of adverse pregnancy outcomes. If glycemic control is inadequate, additional medications are needed. A large body of evidence has shown that metformin is also an effective medication in GDM. Compared to immediate-release (IR) formulation, the prolonged-release (PR) formulation of metformin offer some advantages with once-daily dosage and less frequent side effects, leading to better compliance. To date, there is no study specifically report the effectiveness of the use of metformin PR in the treatment of GDM, as well as the time to achieve glycemic control after treatment.

Objective:

To evaluate the effectiveness of metformin PR in the treatment of GDM in terms of glycemic control within 6 weeks, time to achieve glycemic control, and associated factors.

Methods:

A randomized, double-blind, placebo-controlled clinical trial will be conducted among 80 pregnant women diagnosed with GDM who had inadequate glycemic control. The women will be randomized into 2 equal group, either receiving metformin PR or placebo, in addition to nutritional therapy and behavioral modification. Dosage adjustment will be made every 2 weeks as per obstetrician’s discretion. If glycemic target is not achieved within 6 weeks, insulin therapy will be initiated. All the participants and the investigators are blinded to the treatment provided. The primary outcome is the rate of achievement of glycemic control and secondary outcomes are time to achievement of glycemic control, rate of insulin therapy, and factors associated with the success of metformin PR use.

Results:

As of June 2025, the study has recruited 12 participants.

Conclusions:

The results of this study will provide additional information on the use of metformin in the treatment of GDM, including use of different formulations, rate of glycemic control, time to achieve glycemic control, and associated factors. This will help physicians plan better care of pregnant women with GDM, especially when glycemic control is inadequate, including choices of metformin formulation, dosage and follow-up schedule, identification of women at risk for treatment failure, etc. Clinical Trial: This protocol has been registered to the Thai Clinical Trial Registry (Trial registration number TCTR20250525007).