Could it be that quitting smoking reduces diabetes risk?

This article discusses smoking as a risk factor for type 2 diabetes, and whether quitting smoking reduces diabetes risk.

Smoking is bad for a lot of things. We all know about lung cancer and heart attacks. However, smoking can also increase your chances of getting type 2 diabetes.

Being a current smoker increases your risk for developing diabetes by about 40-50% (1). This is approximately the same increase as you would get from drinking two cans of soft drink every day (2). And like that soft drink, the more you have every day the greater your chances of getting diabetes.

So if you smoke more than 20 cigarettes per day this will double your risk of developing type 2 diabetes.

How does smoking cause diabetes?

How smoking leads to diabetes is uncertain. Some believe chemicals in tobacco smoke impair the function of the hormone insulin, whose job it is to regulate your glucose levels.

In people who are overweight or inactive, insulin already has a hard time keeping things under control. So smoking is just one more burden on insulin and, eventually, something has to give.

Smoking also reduces blood flow to your muscles, meaning they are less able to take up extra glucose from your blood stream.

In addition, chemical components of tobacco smoke can cause damage to the beta-cells of the pancreas, whose job it is to make insulin and control your blood glucose levels.

But while smoking increases your risk, there is good evidence that quitting can reduce your chances of getting diabetes. Ex-smokers certainly have a lower risk of diabetes and its complications in the long term than those who continue to smoke regularly.

Can quitting cause diabetes?

However, quitting is not easy on you or your body. Some recent data even suggests that those who have recently stopped smoking continue to have an increased risk of diabetes, at least in the first few years (4).

But in the longer term (more than five years) the risk of diabetes is certainly lower.

One reason for this blip in diabetes when you give up smoking may be that for some people, giving up means they gain weight. People who stop smoking often complain that they eat more, while at the same time their metabolic rate is lower, meaning they don’t burn the excess calories. And excess calories mean excess waist.

But while weight gain after quitting is real, it is usually a small amount and temporary, and the health benefits of quitting more than make up for this.

As you begin to feel healthier and are able to be more active, weight levels will often return to previous levels, or lower. 

However, the short term risk of diabetes seems to be increased even in people who don’t gain weight after quitting (5).

Another reason why those who have recently stopped smoking still have an increased risk of diabetes may be that the effects of being a smoker lingers for several years and takes a good while to shift. So the sooner you stop the better.

How to quit

As quitting smoking reduces diabetes risk and its complications, it may be one of the most important things you do.

The best way to stop smoking is, however, controversial.

There are medications such as patches and nicotine lozenges, and a regular exercise regime also helps. But it’s hard to do on your own.

Smoking is a powerful addiction that is understandably hard to break. You have the best chance of quitting if you get some help. There are lots of people and effective therapies that can help you stop smoking.

Individually, they won’t work the same for everyone, or in all cases. But it is usually possible to find one that will work for you. Talk to your doctor or call you’re local quit line to find out the options that best suit your needs.


  1. Willi C, Bodenmann P, Ghali WA, Faris PD, Cornuz J: Active smoking and the risk of type 2 diabetes: a systematic review and meta-analysis. JAMA 2007;298:2654–2664
  2. The InterAct consortium. Consumption of sweet beverages and type 2 diabetes incidence in European adults: results from EPIC-InterAct. Diabetologia. 2013 Apr 26. [Epub ahead of print]
  3. Berlin I. Smoking-induced metabolic disorders: a review. Diabetes Metab. 2008 Sep;34(4 Pt 1):307-14.
  4. Yeh H-C,Duncan BB, Inês Schmidt M, et al. Smoking, Smoking Cessation, and Risk for Type 2 Diabetes Mellitus. Ann Intern Med January 2010: 152; 10-17
  5. Oba S, Noda M, Waki K, Nanri A, Kato M, Takahashi Y, Poudel-Tandukar K, Matsushita Y, Inoue M, Mizoue T, Tsugane S; for the Japan Public Health Center-based Prospective Study Group. Smoking Cessation Increases Short-Term Risk of Type 2 Diabetes Irrespective of Weight Gain: The Japan Public Health Center-Based Prospective Study. PLoS One. 2012; 7(2)


Last Reviewed: 15-Jun-2017

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Dr Merlin Thomas

Professor Merlin Thomas is Professor of Medicine at Melbourne’s Monash University, based in the Department of Diabetes. He is both a physician and a scientist. Merlin has a broader interest in all aspects of preventive medicine and ageing. He has published over 270 articles in many of the worlds’ leading medical journals

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