The association between smoking cessation and glycaemic control in patients with type 2 diabetes: a THIN database cohort study

Lycett, Deborah; Nichols, Linda; Ryan, Ronan; Farley, Amanda; Roalfe, Andrea; Mohammed, Mohammed A.; Szatkowski, Lisa; Coleman, Tim; Morriss, Richard K.; Farmer, Andrew; Aveyard, Paul

Abstract

Background

Smoking increases the risk of developing type 2 diabetes. However, several population studies also show a higher risk in people 3–5 years after smoking cessation than in continuing smokers. After 10–12 years the risk equates to that of never-smokers. Small cohort studies suggest diabetes control deteriorates temporarily during the first year after quitting. We examined whether or not quitting smoking was associated with altered diabetes control in a population study, for how long this association persisted, and whether or not this association was mediated by weight change.

Methods

We did a retrospective cohort study (Jan 1, 2005, to Dec 31, 2010) of adult smokers with type 2 diabetes using The Health Improvement Network (THIN), a large UK primary care database. We developed adjusted multilevel regression models to investigate the association between a quit event, smoking abstinence duration, change in HbA1c, and the mediating effect of weight change.

Findings

10 692 adult smokers with type 2 diabetes were included. 3131 (29%) quit smoking and remained abstinent for at least 1 year. After adjustment for potential confounders, HbA1c increased by 0·21% (95% CI 0·17–0·25; p<0·001; [2·34 mmol/mol (95% CI 1·91–2·77)]) within the first year after quitting. HbA1c decreased as abstinence continued and became comparable to that of continual smokers after 3 years. This increase in HbA1c was not mediated by weight change.

Interpretation

In type 2 diabetes, smoking cessation is associated with deterioration in glycaemic control that lasts for 3 years and is unrelated to weight gain. At a population level, this temporary rise could increase microvascular complications.

Citation

Lycett, D., Nichols, L., Ryan, R., Farley, A., Roalfe, A., Mohammed, M. A., Szatkowski, L., Coleman, T., Morriss, R. K., Farmer, A., & Aveyard, P. (2015). The association between smoking cessation and glycaemic control in patients with type 2 diabetes: a THIN database cohort study. Lancet Diabetes and Endocrinology, 3(6), https://doi.org/10.1016/S2213-8587%2815%2900082-0

• Journal Article Type: Article
• Publication Date: Jun 1, 2015
• Deposit Date: Feb 11, 2016
• Publicly Available Date: Feb 11, 2016
• Journal: Lancet Diabetes & Endocrinology
• Print ISSN: 2213-8587
• Electronic ISSN: 2213-8595
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 3
• Issue: 6
• DOI: https://doi.org/10.1016/S2213-8587%2815%2900082-0
• Public URL: https://nottingham-repository.worktribe.com/output/983404
• Publisher URL: http://dx.doi.org/10.1016/S2213-8587(15)00082-0
• Additional Information: Copyright Elsevier 2015