Abstract

Objective: This study examined the influence of smoking on glycaemic control in individuals with type 1 diabetes (T1D) using flash continuous glucose monitoring (F-CGM) systems, as well as its potential mediating role in the relationship between socioeconomic status (SES) and glycaemic control. Methods: This study included 378 subjects with T1D (18% smokers). Glucose metrics cloud downloads were obtained over a period of 14 days. Mean annual net income per person based on census tract data was used as a proxy for SES. Mediation analysis was performed using four-way effect decomposition procedures. Results: Smokers exhibited significantly lower net income than non-smokers (p < 0.001). Compared to smokers, non-smokers showed better glycaemic control characterized as higher time in range (TIR) 70–180 mg/dL (p = 0.002) and lower glycosylated haemoglobin levels (p = 0.008). Mediation analysis revealed a significant mediating role of smoking in the relationship between SES and glycaemic control (TIR). Conclusions: Our data suggest that smoking exerts a detrimental effect on glycaemic control in individuals with T1D using F-CGM systems. In addition, tobacco use partially mediates the relationship between SES and glycaemic control. Thus, adopting smoking cessation measures could lead to improved glycaemic control and help mitigate the impact of social inequalities on T1D. © The Author(s), under exclusive licence to Tehran University of Medical Sciences 2024.