Table 1.

The results of studies evaluating the effect of smoking cessation on hemoglobin A1c in diabetic patients

Ref.	Country/region	Study population	Study design	Effect
Dinardo et al[24], 2019	United States	T2D, n = 282	Cross-sectional, comparison of current smokers vs former smokers and never-smokers	Positive
Braffett et al[14], 2019	Multicenter (United States and Canada)	T1D, n = 1441	Retrospective analysis of the prospective cohort study, comparison of current smokers vs former smokers and never-smokers	Positive
Lycett et al[17], 2011	United Kingdom	T2D, n = 10692	Retrospective cohort study, observation of HbA1c in three groups: Continual smokers, long-term quitters, and relapsers	Negative
Ohkuma et al[23], 2015	Japan	T2D, n = 2490	Cross-sectional study, comparison of current smokers and former smokers vs never-smokers	Positive
Su et al[26], 2017	China	T2D, n = 7763	Cross-sectional study, comparison of current smokers, former smokers and never-smokers	Positive
Li et al[28], 2017	Hong Kong of China	T2D, n = 557	A randomized controlled trial, comparison of level of HbA1c and changes from baseline to 12-mo between quitters and non-quitters	Neutral
Kar et al[29], 2016	United States, Japan	T1D + T2D, n = 13719	Metanalysis, comparison of current smokers vs quitters	Neutral
Voulgari et al[57], 2011	Greece	T2D, n = 193	Prospective study, comparison of smokers vs former-smokers	Positive
Feodoroff et al[69], 2016	Finland	T1D, n = 3613	Prospective study, comparison of smokers vs non-smokers and former-smokers vs non-smokers	Positive
Reynolds et al[68], 2011	United States	T1D, n = 2124	Cross-sectional analysis of population-based study, comparison of current smokers vs non-smokers and former-smokers vs non-smokers	Neutral
Reynolds et al[68], 2011	United States	T2D, n = 348	Cross-sectional study, comparison of current smokers vs non-smokers and former-smokers vs non-smokers	Neutral

T1D: Type 1 diabetes; T2D: Type 2 diabetes; HbA1c: Hemoglobin A1c;