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Expert-reviewed by Ashwini S.Kanade, Registered Dietician and Certified Diabetes Educator with 17 years of experience

The relationship between smoking and heart disease and smoking and lung cancer is already well known. However, long-term studies have now confirmed that smoking can also cause type 2 diabetes.

Those who smoke are about 30-40% more likely to develop diabetes than those who don’t. The greater the number of cigarettes one smokes per day, greater is their risk of developing type 2 diabetes. If someone already has diabetes and also smokes, they’re only making it more difficult for themselves to control the disease. (1)

How is diabetes connected to smoking?

The chemicals in cigarettes cause cell injury and inflammation. They also cause oxidative stress and damage. Research shows that both these factors – inflammation and oxidative stress – tend to increase the risk of diabetes. (2) To combat the effects of oxidative stress due to smoking, having food rich in antioxidants, such as amla (Indian gooseberry), rajma (kidney beans), green tea and green leafy vegetables, is highly recommended.

People who smoke are also more likely to develop belly fat which tends to increase the body’s production of a hormone called cortisol. This cortisol is known to increase blood sugar levels. (3)

Smoking can affect diabetes control

Research has shown that high levels of nicotine tend to reduce the effect of insulin. That means a person with diabetes who also smokes will need a higher dose of insulin to maintain a healthy blood sugar.

There is also evidence that chronic smokers with type 2 diabetes show greater insulin resistance than non-smokers. (4) Insulin resistance is a condition when the body stops responding to insulin. This, again, implies that people with diabetes who are already on insulin will require higher doses of insulin to maintain their blood sugars.

Smoking can complicate your diabetes

When persons with diabetes smoke, they increase their risk of developing serious diabetic complications such as heart disease, kidney disease, retinopathy and peripheral neuropathy. (1) 

Read the eight early signs of diabetes complications that you might be ignoring.

Dr. Vatsala Kashi, a physician, points out, “People with diabetes are more likely to suffer from high levels of unhealthy LDL cholesterol. Studies have also shown that cigarette smoking tends to lower the levels of healthy, HDL cholesterol. So, when people with diabetes smoke, they’re actually putting themselves at greater risk of developing heart disease.”

And if you still have doubts, here’s the clincher…

Cutting down on smoking has been found to improve glycemic control

In a study, 34 diabetic smokers who stopped smoking were followed for a year. It was found that cessation of smoking was associated with an improvement in HbA1c levels. (5)

How to quit smoking

Now you’re probably wondering how to quit smoking. Here are a few tips that can help:

  • Prepare yourself mentally and medically to quit. Because smoking is an addiction, quitting all of a sudden is likely to lead to withdrawal symptoms because your brain is being deprived of nicotine. Talk to your doctor about what to expect, and get necessary support systems in place.
  • Talk to your doctor about using nicotine replacement therapy to deal with withdrawal symptoms such as headaches, mood swings and fatigue.
  • Quitting smoking can be tough; take support from your family and friends to get through this difficult time. Or look for a counsellor or therapist who can help you learn how to practice behaviour therapy to stick to your quit-smoking decision.
  • Avoid stressful situations that can trigger a break in your resolve to quit. Learn to manage your stress better. Strategies like keeping busy, listening to music, walking, exercising and meditation can help. Find what works best for you.
  • Identify the triggers that set off your craving for a smoke – and avoid them diligently. If you feel like smoking when with certain people who smoke, keep away from them. If you generally smoke while relaxing after dinner, go for a walk instead. Maybe the smell of cigarette smoke makes you crave them – clean up your house, car and clothes to rid them of this smell.
  • If you quit smoking for a while and then find you’ve relapsed, don’t be too harsh on yourself. Many people have to make many attempts before they are able to quit smoking for good. What’s important is to not stop trying. Work up a strong motivation to stay healthy, and it will not be long before you are free of this unhealthy habit.

Also, read about the effects of alcohol on diabetes.

Dr. Vatsala Kashi (M. D.), is a consultant physician at Ramakrishna Nursing Home, Bengaluru.


  1. CDC: Smoking and Diabetes
  2. C.P. Domingueti, L.M. Dusse, Md. Carvalho, L.P. de Sousa, K.B. Gomes, A.P. Fernandes. Diabetes mellitus: The linkage between oxidative stress, inflammation, hypercoagulability and vascular complications. J Diabetes Complications. 2016 May-Jun;30(4):738-45. doi: 10.1016/j.jdiacomp.2015.12.018.
  3. CDC: Surgeon General’s report on smoking and health
  4. G. Targher, M. Alberiche, M.B. Zenere, R.C. Bonadonna, M. Muggeo, E. Bonora. Cigarette smoking and insulin resistance in patients with noninsulin-dependent diabetes mellitus. J Clin Endocrinol Metab. 1997 Nov;82(11):3619-24. Available online at:
  5. J.E. Gunton, L. Davies, E. Wilmshurst, G. Fulcher, A. McElduff. Cigarette Smoking Affects Glycemic Control in Diabetes. American Diabetes Association. Diabetes Care 2002 Apr; 25(4): 796-797.

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Disclaimer: The information provided in this article is for patient awareness only. This has been written by qualified experts and scientifically validated by them. Wellthy or it’s partners/subsidiaries shall not be responsible for the content provided by these experts. This article is not a replacement for a doctor’s advice. Please always check with your doctor before trying anything suggested on this article/website.


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