Exploring the Effect of Exercise versus Metformin on Insulin Resistance amongst Nigerians with Pre-diabetes: A Randomised Controlled Trial

Background: Pre-diabetes is an important risk factor for the development of type 2 diabetes and is common in Nigeria. Effective intervention can reverse the underlying pathogenesis of insulin resistance in pre-diabetes. This study aimed to determine and compare the impact of moderate exercise and metformin interventions on insulin resistance among participants with pre-diabetes. Materials and Methods: Using a randomised placebo-controlled design, 54 Nigerians with pre-diabetes were selected using simple random sampling. They were offered metformin, moderate exercise or placebo treatment and followed up for 12 weeks. Insulin resistance was assessed before and after the interventions and the outcome was compared. Results: Forty-nine participants with pre-diabetes completed the study. Participants in both the exercise and metformin groups had significantly decreased insulin resistance compared to placebo after 12 weeks of intervention. However, there was a decrease in insulin resistance by 77.3% (homeostasis model assessment-insulin resistance [HOMA-IR]) and an increase in insulin sensitivity by 81.2% (quantitative insulin sensitivity check index [QUICKI]) in the exercise group. In comparison, participants in the metformin group had a decrease in insulin resistance by 66.3% (HOMA-IR) and an increase in insulin sensitivity by 76.2% (QUICKI). Conclusion: Amongst Nigerians with pre-diabetes, both moderate exercise and metformin have significantly higher efficacy than placebo in improving insulin resistance. However, moderate exercise improved insulin resistance more than the metformin intervention. Participants in this study need to be followed up for a longer period to assess the long-term effects of these interventions.