Analysis of lifestyle factors related to improving blood glucose metabolism by continuous glucose monitoring: a multicenter study in the Chikugo region

Background: Although lifestyle-improving effects of continuous glucose monitoring (CGM) have long been suggested, it remains unclear which lifestyle changes contribute to improvements in blood glucose control. This multicenter study evaluated the effect of CGM on glycosylated hemoglobin (HbA1c) and identified lifestyle factors associated with its improvement. Methods: We retrospectively investigated changes in insulin injection methods and lifestyle habits after starting CGM via a questionnaire and analyzed the associations between these changes and the degree of reduction in HbA1c over a 6-month period. Results: Wearing a CGM device reduced HbA1c by a mean of 0.83% (median 0.5%), regardless of sex or age. This reduction was smaller in individuals with type 1 diabetes and in those receiving insulin injections 3 or more times per day. Changes in insulin injection doses were not the primary cause of the reduction in HbA1c. Increased insulin doses and more frequent adjustments were not associated with lower HbA1c. After adjusting for HbA1c levels at the start of CGM use, dietary changes associated with HbA1c improvement included reduced intake of carbohydrates and foods that increase blood glucose levels and decreased meal skipping. Increases in resistance exercise and postprandial exercise were also associated with this improvement. Conclusions: The decrease in HbA1c levels after starting CGM was driven primarily by participants becoming aware of fluctuations in blood glucose levels due to diet and exercise, and making lifestyle changes to improve glycemic control.