Stopping smoking affects diabetes

Q: WHAT impact does quitting smoking have on outcomes for people with type 2 diabetes?

A: Quitting smoking can reverse the risk of macrovascular complications for people with diabetes. Overall, the benefits of quitting smoking far outweigh any disadvantages, such as weight gain.1,2

In a longitudinal study following almost 35,000 UK male general practitioners (with and without type 2 diabetes) for 50 years, smokers who did not quit died on average about 10 years earlier than lifelong non-smokers. However, men who quit at age 30, 40, 50 or 60 years regained 10, 9, 6 and 3 years of life, respectively.3

The Nurses’ Health Study – a cohort of more than 120,000 US women followed for 20 years – found a dose-response relationship between current smoking status and risk of coronary heart disease among the 6547 women with type 2 diabetes.4

Compared with lifelong non-smokers, the relative risk increased by 21% for past smokers, 66% in women who currently smoked 1–14 cigarettes per day, and almost tripled in women who currently smoked 15 or more cigarettes per day (p < 0.001).

Quitting reduces the risk of cardiovascular disease. In the Nurses Health Study, the risk of an event was similar in women with diabetes who were lifelong non-smokers and women with diabetes who had stopped smoking for more than 10 years (RR 1.01, 95% CI 0.73 to 1.38).4

Similarly, in the UKPDS the risk of coronary heart disease was the same in people who had never smoked and ex-smokers but was significantly increased in people who were current smokers (HR 1.41, 95% CI 1.06 to 1.88).5

References
1.        Diabetes Australia, Royal Australian College of General Practitioners. Diabetes management in general practice: Guidelines for type 2 diabetes. 17th edn, 2011/2012 Canberra, 2011

2.        Cardiovascular Writing Group. Therapeutic Guidelines: Cardiovascular, Version 5 [eTG complete CD-ROM]. Melbourne: Therapeutic Guidelines Ltd, 2008.

3.        Doll R, Peto R, Boreham J, et al. Mortality in relation to smoking: 50 years’ observations on male British doctors. Bmj 2004;328:1519. http://www.ncbi.nlm.nih.gov/pubmed/15213107

4.        Al-Delaimy WK, Manson JE, Solomon CG, et al. Smoking and risk of coronary heart disease among women with type 2 diabetes mellitus. Arch Intern Med 2002;162:273-9. http://www.ncbi.nlm.nih.gov/pubmed/11822919

5.         Turner RC, Millns H, Neil HA, et al. Risk factors for coronary artery disease in non-insulin dependent diabetes mellitus: United Kingdom Prospective Diabetes Study (UKPDS: 23). Bmj 1998;316:823-8. http://www.ncbi.nlm.nih.gov/pubmed/9549452