Smoking and diabetes: How smoking can affect your blood sugar levels?

Introduction

Smoking increases your risk of type 2 diabetes—and the more you smoke, the more likely you are to develop type 2 diabetes.

In this post, we’ll take a closer look at the facts about smoking and diabetes and the links between them. We’ll learn about the complications caused by each, and how the risk of developing those complications increases if a person has diabetes and continues to smoke.

We’ll also see how giving up smoking can help reduce the risk of complications associated with diabetes and protect your health in general.

Cigarette smoking is a risk factor for type 2 diabetes

A lot of research has been carried out into the links between cigarette smoking and diabetes. The Centers for Disease Control and Prevention (CDC), a department of the United States Government, has studied this research and found that

Smoking is an important risk factor for the development of type 2 diabetes.
Smoking is a modifiable risk factor for the development of type 2 diabetes. If you quit smoking, you can reduce your risk.
People who smoke cigarettes are 30–40% more likely to develop type 2 diabetes than people who don’t smoke.
The more you smoke, the higher your risk of developing type 2 diabetes.
Smoking makes diabetes harder to manage and increases the risk of developing serious complications.

How smoking increases your risk of type 2 diabetes

There are three main types of diabetes—type 1, type 2 and gestational diabetes.

Type 2 diabetes is where the body resists the normal effects of insulin and becomes unable to produce enough of it to meet the body’s needs. This can lead to serious problems if blood glucose levels are high for long periods of time. Type 2 is the most common type of diabetes—almost 1.3 million Australians are currently living with it.

The signs of type 2 diabetes include:

frequently needing to urinate
increased thirst
tiredness
feeling hungry
having cuts that heal slowly.

If you have these signs, your doctor can arrange for you to have tests that will determine if you have diabetes. However the most common symptom is in fact no symptom at all, so it is good to have regular health checks and to check your personal level of risk based on factors such as smoking.

The good news is that type 2 diabetes can often be prevented or delayed by making lifestyle changes such as eating healthily, being active and quitting smoking.

Quitting smoking is important in the prevention of type 2 diabetes. This is because smoking changes the pancreas’ ability to produce insulin while also contributing to insulin resistance. This causes a build-up of glucose in the blood, which leads to diabetes. Smoking also damages the tissues within our blood vessels, and that plays a major role in the development of heart disease.

The complications of smoking

Smoking is one of the biggest causes of preventable illness and death in Australia.

Every single puff on a cigarette causes over 7000 chemicals to enter the lungs and then rapidly spread all around the body. These chemicals include 69 carcinogens (substances that produce cancer), and there are 16 types of cancer that can be caused by smoking. These include cancer of the mouth and throat, lung cancer, colon cancer and pancreatic cancer.

Smoking also damages your heart and your blood circulation, which increases your risk of developing conditions that include:

coronary heart disease (CHD)
heart attack
stroke
chronic obstructive pulmonary disease (COPD)
pneumonia.

Smoking can also reduce the fertility of both men and women.

Given these complications, it’s surprising that people continue to smoke; yet they do. According to the Australian Bureau of Statistics, in 2020-21, one in ten people (10.7% or 2.1 million people) aged 18 years and over were current daily smokers, with men more likely than women to smoke daily (12.6% compared to 8.8%). The smoking rate increased with age until 55-64 years where it peaked at 13.7%, and then declined for older age groups.

The high number of people who continue to smoke despite the well-publicised risks shows how difficult it is to quit.

This is because of the effects of nicotine.

The short- and long-term effects of nicotine

Nicotine is a chemical that is contained in tobacco leaves. It is highly addictive, and people smoke in order to experience its short-term effects—or at least some of them.

When a person inhales cigarette smoke, it takes less than 10 seconds for nicotine to travel through the bloodstream and reach the brain. Once it arrives there, it works with neurotransmitters (chemicals that allow messages to travel around the brain) to produce temporary feelings of calmness, increased focus and alertness. These are the pleasant sensations that cause people to smoke. The fact that they wear off quickly increases people’s urge to smoke more and more frequently.

Nicotine can also have the following short-term effects:

increased muscle activity
headache
dizziness/light-headedness
nausea and vomiting
abdominal cramps
weakness
increased heart rate and blood pressure

Using nicotine regularly over a long period of time (usually via cigarettes) is thought to be involved in the development of:

high blood pressure
periodontitis (gum disease)
reduced fertility in men and women
male sexual dysfunction
rheumatoid arthritis

Nicotine use in pregnancy can damage the unborn child’s brain and lungs. It also increases the risk of ectopic pregnancy and stillbirth.

Research suggests that nicotine is a cause of insulin resistance. This is where the body is not able to use insulin as it should, which can lead to people developing pre-diabetes and then, potentially, type 2 diabetes.

Consuming nicotine over a long period of time can result in dependence, which is where people find it very hard to stop using a substance. This can lead both to the complications of smoking mentioned above and to the complications of type 2 diabetes.

The complications of diabetes

Diabetes can have serious negative impacts on physical and mental health. The potential complications of types 1 and 2 diabetes include:

heart disease
kidney disease
stroke
poor circulation in the legs and feet
eye disease.
erectile dysfunction
Alzheimers disease
hearing impairment
nerve damage
skin and mouth conditions
depression

People with type 1 diabetes or type 2 on insulin who smoke may need a larger dose of insulin than non-smokers to manage their glucose levels.

Here are some facts that show how serious a problem diabetes is:

People with diabetes are up to four times more likely to experience heart attacks and strokes
Diabetes is the leading cause of preventable blindness in Australia
Kidney failure is three times more common in people with diabetes
Amputations are 15 times more common in people with diabetes
More than 30% of people with diabetes experience depression, anxiety and distress.

If someone has diabetes and also smokes, the risk of these complications increases dramatically. This is one of the many reasons why preventing type 2 diabetes is so important, and the key to this is healthy habits.

Healthy habits to manage blood glucose

We need glucose (sugar) in our blood as it is our cells’ main source of energy. But blood sugar levels have to be kept within a healthy range, which our body usually does by producing the hormone insulin. Insulin enables the cells to use blood sugar effectively, which stops it from building up too much glucose in the blood.

If insulin becomes unable to do its job or insufficient quantities of it are produced, blood glucose levels go outside the optimal range. When that occurs on a consistent basis, there can be serious consequences. Having too much glucose in the blood (hyperglycaemia) can lead to chronic health conditions such as heart disease and diabetes.

Several factors can make our blood glucose levels rise above the optimal range. These include:

food—especially the type and amount of carbohydrates we eat
how physically active we are
illness
injury
medications —missing or delaying usual medications for diabetes, using out-of-date or incorrect doses of medication or injecting incorrectly)
emotional stress.

The most common symptoms of hyperglycaemia are:

frequently needing to urinate
increased thirst
tiredness
weight loss
blurred vision
developing infections.

A simple blood test will show how much glucose you have in your blood. It is particularly important to find out if you have hyperglycaemia because, as we mentioned previously, it is associated with the development of type 2 diabetes and pre-diabetes (where your blood sugar is high, but not high enough to be classified as diabetes). But other conditions can also cause high blood glucose levels. These include Cushing’s disease and polycystic ovarian syndrome (PCOS) or from taking certain medications. For this reason, your doctor may suggest repeating the test.

If pre-diabetes is confirmed, it’s time to take action—this is a condition that can increase your risk of developing type 2 diabetes by 10 to 20 times.

Fortunately, if you do take action, type 2 diabetes can be prevented in many cases. There are many things you can do to lower your blood glucose levels if you have pre-diabetes, including eating a nutritious diet. Exercise, maintaining a healthy weight, getting enough sleep and finding healthy ways of tackling stress also help.

Medications and insulin for diabetes management

There are many types of medicines that can be used to support the management of diabetes. Their aim is to keep your blood glucose levels within the optimal range to reduce your chances of experiencing complications.

Talk with your doctor about the options available and the benefits to each to find the right treatment for you. This will depend on what type of diabetes you have, your lifestyle and any other health conditions you may have.

Treating type 2 diabetes

Some people who have recently been diagnosed with type 2 diabetes may not need any medication. Others will, especially if making healthy lifestyle changes such as changing their diet, being more active and maintaining a healthy weight are not enough to manage their blood sugar levels.

There is a growing number of types of medication that are available. Their doctor may prescribe one or more of those and/or what is known as supplementary insulin.

Medication

Metformin

Metformin is the most common medicine for type 2 diabetes, and is usually the first to be offered. It helps insulin to work effectively and reduces the amount of the glucose that is stored up inside the liver from being released. Metformin is also used to treat gestational diabetes.

Some people need to take other medicines alongside, or instead of, metformin.

These include:

DPP-4 inhibitors—also known as gliptins, these increase the amount of insulin that your pancreas makes and reduce the amount of stored glucose that is released from your liver.
SGLT2 inhibitors—also known as gliflozins, these increase the amount of glucose that is removed from your body in urine.
Sulfonylureas—these cause the pancreas to release more of the insulin that’s produced by your body.
Alpha glucosidase inhibitor—in Australia there is only one medication (Acarbose) in this class of drug. It works by preventing carbohydrates from being broken down into glucose.
Thiazolidinediones—also known as glitazones. Again, there is only one medication of this type available in Australia (pioglitazone). This helps your insulin to work more effectively and reduces insulin resistance.

Non-insulin injectables

These are medications for type 2 diabetes that are injected and do not contain insulin. What they do is stimulate the pancreas to produce insulin. They also decrease the speed at which your stomach empties, making you feel full for longer and decreasing your appetite.

Non-insulin injectables include:

Dulaglutide
Liraglutide
Semaglutide
Tirzepatide

Supplementary insulin

People who live with type 2 diabetes may eventually need insulin injections. This is because, over time, type 2 causes the cells that produce insulin to be less and less efficient. This means that their own insulin will need to be supplemented.

Supplementary insulin is injected using a syringe, pen needle or insulin pump. Your doctor or diabetes specialist will teach you how to do this.

Treating type 1 diabetes

Lifelong insulin replacement is needed as the body produces little or no insulin.

Treating gestational diabetes

People with gestational diabetes may be given Metformin or supplementary insulin. Both are safe for mother and baby and are usually stopped after the baby is born.

Whichever type of diabetes you have, your doctor will recommend the appropriate treatment for you.

Does the risk of diabetes go away if you stop smoking?

Some research has indicated that quitting smoking actually increases the risk of type 2 diabetes. This could be because nicotine is an appetite suppressant, so people who do stop smoking may experience weight gain. Other research suggests that this increased risk of diabetes when you quit only applies to heavy smokers. But even in heavy smokers, the risk of diabetes drops over the long term. After about 10 years, the increased risk of developing diabetes disappears completely.

As soon as a person stops smoking, their body starts to recover from all of its harmful effects. Their risk of heart disease decreases, which is especially beneficial to people living with diabetes.

Conclusion

Tobacco smoke is a modifiable factor for developing diabetes. Smoking also increases the risk of diabetes-related complications in people who are already living with the condition. When you consider that, as well as the damage that smoking does to your health in general, the importance of quitting is clear. But, as we have seen, giving up smoking is not an easy thing to do. Fortunately, help is available: visit Quit.org.au for resources and support to help you quit smoking. Quit also has counsellors you can speak to.

As well as stopping smoking, there are other things you can do to reduce your risk of type 2 diabetes.

The Life! program can help you.

Life! is a free healthy lifestyle program that helps you improve your eating habits, increase your physical activity and manage stress. You can choose from a group course or our telephone health coaching service.

Since 2007, over 75,000 Victorians have learnt more about living a healthy life with the Life! program. It is the largest prevention program of its kind in Australia.

Life! is funded by the Victorian government and managed by Diabetes Victoria.

You can take a quick online health test and check your eligibility for the program here.

Sources

15 Easy Ways to Lower Blood Sugar Levels Naturally – healthline

16 cancers caused by smoking – Cancer Council NSW

Causes of Death, Australia, 2021 – Australian Bureau of Statistics

Cigarette smoking and diabetes mellitus: evidence of a positive association from a large prospective cohort study – OUP Academic

Diabetes My Way – NHS

Diabetes: Australian facts, Smoking – Australian Institute of Health and Welfare

How does tobacco deliver its effects? – National Institute on Drug Abuse

Insulin and Non-insulin Injection Devices for Diabetes – Healthdirect

Most Common Symptoms of Bipolar Disorder – Verywell Mind