Does Quitting Smoking Cause Low Blood Sugar?

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Nicotine withdrawal causes a whole host of symptoms that can leave new ex-smokers feeling shaky and uncomfortable, but to date, research has not shown a direct link between quitting smoking and low blood sugar.

Blood sugar is affected by both smoking and smoking cessation, however. Let's take a closer look at how it happens.

How Smoking Affects Blood Sugar

Once inhaled, the nicotine in cigarette smoke slows the release of insulin, a hormone that helps sugar get into the cells of our bodies where it can be used for energy.

Insulin also removes excess sugar from the blood when necessary. Because of this, smokers tend to be slightly hyperglycemic, meaning that they have too much sugar in their blood. In this way, nicotine acts as an appetite suppressant. It also puts smokers at risk for type 2 diabetes.

Smoking Cessation and Blood Sugar

When a person stops smoking, elevated blood sugar from the presence of nicotine settles back to normal levels in time, though research has shown that initially, smoking cessation may cause blood sugar to rise a small amount for some people. More on that below.

Science has not yet uncovered definitive proof that smoking cessation causes a drop in blood sugar, but some research has been done on this as well.


In 2012, Dr. Marietta Stadler and her team conducted a study to better understand how quitting smoking affects blood sugar. A small group of smokers who were smoking at the start of the study, but quit smoking during the research were monitored for blood sugar changes.

Insulin secretions were measured before and after cessation (at three and six months smoke-free) on these people.

It was found that these new ex-smokers released a bit more insulin at three months smoke-free than they did while smoking. Additionally, they appeared to gravitate more to high carbohydrate food when given the choice at a buffet than they did when actively smoking.

The researchers think that this spike in insulin (which can, in turn, cause low blood sugar in certain circumstances) might play a part in why new ex-smokers seem to crave more carbohydrates (sugar). It appears to be a temporary effect of smoking cessation, however, disappearing after six months smoke-free.

"We believe that the alterations in insulin secretion could possibly be related to the increased carbohydrate cravings and weight gain experienced by many smokers who give up, explains Dr. Stadler. "However, the increase in insulin secretion and carbohydrate intake seems to be a transient effect of stopping smoking, as these changes were not seen any more after six months, even though the participants had gained more weight."

It is important to note that this was a small study of 27 people, and no further research has been reported on as of yet. It does suggest, however, that more investigation is needed in this area.

How Smoking Cessation Can Cause Blood Sugar to Rise 

Research conducted at Johns Hopkins School of Medicine suggests that quitting smoking may put some ex-smokers at risk for type 2 diabetes because of the weight gain that is so often associated with smoking cessation.

They were quick to remind smokers that the benefits of quitting far outweigh the risks, however, which include heart disease and many forms of cancer.

The takeaway from this is to be mindful of diet and exercise when you stop smoking. While weight gain is common, it is by no means assured. You can avoid most or all of the normal 8- to 10-pound gain if you are careful.

Most people who gain a lot of weight after quitting have significantly changed the eating habits they had as smokers.

Concerns if You're Diabetic

People who have type 2 diabetes may face an increase in blood sugar and associated health risks for the first three years after quitting tobacco.

British researchers reviewed medical records of 10,692 adult smokers (average age of 62) who had been living with diabetes for approximately 6 years. The group included 3,131 people who quit and remained smoke-free for at least one year.

Glycated hemoglobin (commonly referred to as HbA1c or A1c) offers a good picture of a person's blood sugar levels over the past two or three months. A1c levels were measured periodically in both groups. Those who had quit smoking experienced an increase in A1c of approximately 0.21 percent over their smoking counterparts.

By the end of three years, however, A1c had returned to levels equal to that of diabetic smokers.

It is important to note that while this research does point to a temporary increase in blood sugar for diabetic ex-smokers, the positive effects of quitting tobacco are well worth this temporary risk.

New ex-smokers who are diabetic should stay in close touch with their doctors throughout cessation so that blood sugar can monitored and medications adjusted, if necessary.

Sugar Cravings and Dopamine

When nicotine enters the brain, it quickly "docks" with nicotine receptors. This triggers a release of dopamine, and causes smokers to get that rush thought of as "smoking pleasure." Dopamine is often called the feel good hormone because of this. It offers an instant reward and is thought to be the mechanism by which we become addicted to a substance.

Sugar also triggers a dopamine release, so it is a logical replacement for the lack of nicotine that makes ex-smokers edgy and uncomfortable. We eat sugar, get a nice dopamine rush and for a bit, the discomforts of nicotine withdrawal are relieved.

This is not a good substitution, however, because as we all know, sugar cravings that we feed only create more sugar cravings (addiction!) and before long, the bathroom scale starts moving in the upward direction.

A better choice would be to use exercise to relieve nicotine withdrawal. It may take a little discipline to begin with, but working up a sweat also releases dopamine and helps one avoid quit-related weight gain.

Prescription Quit Aids

If you are taking either Zyban (bupropion hydrochloride) or Chantix (varenicline tartrate) to help you quit smoking, it's possible that your appetite is diminished and you're not eating enough.

Both of these medications have the side effect of inhibiting appetite, so it's possible that low blood sugar could occur because of that.

Make sure that you eat enough throughout the day to keep your blood sugar stable. If you're not hungry, eat small meals/snacks every couple of hours, such as an ounce of cheese with an apple or a handful of almonds with a small glass of pure fruit juice.

The Bottom Line

Smoking cessation does influence blood sugar, but to date, science has only definitively shown a correlation between quitting smoking and a rise in blood sugar.

If you are experiencing symptoms of nicotine withdrawal that you suspect are related to low blood sugar, look at how you've been eating on a daily basis, and whether your appetite has been affected by a quit aid.

To remedy low blood sugar, eat small meals or snacks throughout the day. Additionally, make sure that you get enough exercise and rest to offset other discomforts of nicotine withdrawal.

Be patient with yourself. It will take some time to feel normal again once you stop smoking, but you'll regain your balance and will ultimately feel much better than you ever did while smoking.


European Society of Endocrinology. Effects of Smoking Cessation on B-Cell Function, Insulin Sensitivity, Body Weight, and Appetite.

Johns Hopkins School of Medicine. Smoking Cessation May Increase Diabetes Risk.

National Institutes of Health. The Association Between Smoking Cessation and Glycaemic Control in Patients With Type 2 Diabetes: A THIN Database Cohort Study.