Kate Bristow, a diabetes nurse educator, explores the link between hearing loss and diabetes.

Listen to this article below or wherever you get your podcasts or visit our playlist.

While the impact of diabetes on heart, kidney and eye health is well-documented, its association with hearing loss is gaining increased attention recently.

To understand how hearing loss may occur, we first need to understand the effects of diabetes in the body. Diabetes causes small blood vessel disease throughout the body where blood vessels weaken and blood flow through the body is slower.

This impacts function and results in diabetic neuropathy or nerve damage to all parts of the body, including the ear. So, diabetes can affect the nerve endings as well as the system of blood vessels in the ear. This will impact hearing and balance as well as increases susceptibility to infections.

Studies have demonstrated a higher prevalence of hearing loss among people with diabetes compared to those without the condition. According to a 2008 study, individuals with diabetes are twice as likely to experience hearing loss as those without diabetes.

The study analysed data from the National Health and Nutrition Examination Survey (NHANES) and it was found that the risk of hearing impairment was evident across all age groups, suggesting that diabetes may accelerate age-related hearing decline.

The study was a large cohort of nationally representative members of the US population between ages 20 – 69 years old. An association between diabetes and hearing impairment was shown as early as 30 – 40 years old.

Statistics from the Centre of Disease Control and Prevention (CDC) showed that:

• Hearing loss is 30% higher in adults with prediabetes than in those that don’t have it.
• Hearing loss is twice as common in those who have diabetes than in those that don’t.
• Vestibular dysfunction is 70% more likely in people with diabetes. This is a disturbance of the balance system in the body due to problems in the brain or inner ear. Symptoms include vertigo, dizziness, and lack of balance.
• Incidence of falls is 39% higher in people with diabetes. Remember that the ear is also the balance centre of the body.

According to the National Institute of Health (NIH), loss of hearing in adults with diabetes is about twice as common as those who don’t suffer from the condition, and that it may be an under recognised complication of diabetes.

The cause of increase risk

Hearing loss is a complicated condition, often resulting from a combination of genetic, environmental, and physiological factors. For those with diabetes, there are several mechanisms believed to contribute to the increased risk of hearing damage.

1. Microvascular damage: Diabetes is known to cause damage to small blood vessels which can affect the blood supply to the cochlea, a critical structure in the inner ear. Insufficient blood flow can lead to less oxygen and damage to the delicate hair cells responsible for sound transmission.
2. Neuropathy: Just as diabetes can cause peripheral neuropathy, it may also damage the main nerve to the ear, the auditory nerve, as well as other nerves in the auditory system.
3. Chronic inflammation: Elevated blood glucose levels cause inflammation, which may contribute to tissue damage in the auditory system.

Signs of hearing loss

• Asking people to repeat what they said.
• Trouble following conversation in a group setting.
• Thinking that others mumble.
• Difficulty hearing in noisy places.
• Trouble hearing those with quiet voices and small children.
• Turning up the volume on the TV or radio.

Damage to ears may also include balance issues which can lead to falls and fractures, particularly in the elderly.

Hearing loss is common and other causes such as age, disease, noise, and heredity should also be excluded. In other words, diabetes can’t always be blamed.

Hearing loss occurs slowly and may be noticed by those close to the person affected before they notice it themselves.

Questions to be asked

Doctor and diabetes educators should be asking you (patients) the following questions:

• Do you have concerns about you hearing?
• Any hearing and balance screening done regularly – preferably annually? Advocating regular screening of the ears, as we do for the other risk areas of diabetes and referring patients to an audiologist for regular assessment.
• Any recent falls, dizziness or fear of falling?
• Prescribed medications should also be considered as some may be ototoxic.

Neuropathy that occur in diabetes, including hearing loss cannot be reversed. Prevention is better than cure.

Guidelines to protect your ears

• Keeping blood glucose levels as close to target as possible and try to prevent large excursions in blood glucose levels (the highs and the lows or bouncing blood glucose levels). Keeping your blood glucose levels in range is important not only for your hearing. You’ll feel better and have more energy the more you take care of your levels.
• Get your hearing checked every year by an audiologist.
• Avoid other causes of hearing loss such as loud noises.
• Be aware of other causes of hearing loss; there are medications that can cause hearing loss. Discuss this with your doctor.
• Loss of hearing can be very frustrating for you and for those around you. It will negatively impact how you function and your social life.
• Work with a trusted diabetes healthcare team to learn as much as possible about your condition so you’re confident to manage it to the best of your ability.

Final word

Research suggests that hearing loss by diabetes may be due to damage to the nerves and blood vessels in the inner ear and autopsy studies of such patients have shown evidence of this.

This could be due to high blood glucose levels or fluctuating levels over time, damaging small blood vessels and nerves in the inner ear.  Low blood sugar too, affects how nerve signals travel from the inner ear to the brain causing hearing loss, according to the CDC.  Poorly controlled blood glucose levels lead to nerve damage and hearing loss. But reference articles do say that further research is necessary to determine the exact effect of diabetes on hearing.

What is evident is that those who have diabetes shouldn’t neglect their annual hearing tests. Ask your diabetes nurse educator or doctor about a specialist audiologist visit.

References

1. https://diabetes.org/about-diabetes/complications/hearing-loss/diabetes-and-hearing-loss
2. https://www.nih.gov/news-events/news-releases/hearing-loss-common-people-diabetes
3. https://www.cdc.gov/diabetes/diabetes-complications/diabetes-and-hearing-loss.html

Sister Kate Bristow is a qualified nursing sister and certified diabetes educator. She currently runs a Centre for Diabetes from rooms in Pietermaritzburg, providing the network support required for the patients who are members on the diabetes management programme. She also helps patients who are not affiliated to a diabetes management programme on a private individual consultation basis, providing on-going assistance and education to assist them with their self-management of their diabetes.

Header image by FreePik

– OTHER INTERESTING READS –

Dr Angela Murphy looks at the correlation between diabetes and cancer.

Listen to this article below or wherever you get your podcasts or visit our playlist.

A diagnosis of either diabetes or cancer causes significant stress. There is no doubt that if both conditions are present this causes true distress. Although cancer isn’t a typical complication of diabetes, there is an increase in the occurrence of cancer in people living with diabetes (PLWD).

In 2009, the American Diabetes Association and the American Cancer Society developed a consensus document to look at the following questions:

1. Is there an association between diabetes and cancer?
2. What risk factors are common to both diabetes and cancer?
3. What are the biologic links between diabetes and cancer risk?
4. Do diabetes treatments influence risk of cancer?

What is the association between diabetes and cancer?

We see an increasing incidence of both diabetes and cancer. It seems that the diagnosis of both conditions in the same person occurs more frequently than would be expected by chance.

Some cancers (liver, pancreatic, and endometrium) occur more commonly in the presence of diabetes and some cancers (prostate) are less common in the presence of diabetes. Other cancers (lung, kidney, non-Hodgkin lymphoma) haven’t been conclusively shown to have an association with diabetes. Currently the association of cancer and Type 1 diabetes is not confirmed.

In addition to seeing an increase in the incidence of cancer in PLWD, it seems that diabetes increases the risk of complications and mortality from cancer.

What biological association is there between diabetes and cancer?

1. Hyperglycaemia

In the 1920s, scientist Otto Warburg observed that cancer cells consume large amounts of glucose as they rapidly divide and proliferate. This is now called the Warburg effect.

2. Hyperinsulinemia and insulin resistance

Certain cancers possess insulin receptors and stimulation of these by high levels of circulating insulin can directly affect the metabolism of cancer cells, promoting their growth. Insulin also stimulates insulin like growth factor 1 (IGF-1) which promotes cancer cell growth and inhibits cancer cell death. Insulin increases the levels of oestrogen that the body is exposed to which in turn increases the risk of certain cancers, such as breast cancer.

3. Inflammation

Many pro-inflammatory substances (interleukin-6; tumour necrosis factor alpha, etc.) can induce malignant changes in cells and cancer progression. Both hyperglycaemia and hyperinsulinemia cause oxidative stress which in turn causes inflammation. The most common cause of chronic low-grade inflammation is obesity.

What are common risk factors between diabetes and cancer?

1. Obesity

Most people living with Type 2 diabetes are overweight or obese. As mentioned, obesity is a state of low-grade inflammation. The longer overweight or obesity is present, the greater the risk of developing cancer.

The Centre for Disease Control (CDC) in America lists 13 cancers more commonly seen in people living with obesity: oesophageal, breast in post-menopausal women, colon and rectum, uterus, liver, stomach, kidneys, gallbladder, ovaries, pancreatic, thyroid, multiple myeloma, and meningioma, a type of brain cancer.

2. Age

The incidence of most cancers increases with age with an estimated 78% of all newly diagnosed cancer occurring in people over the age of 55 years.

3. Gender

In general, men are slightly more at risk of developing cancer than women and in turn have a higher incidence of Type 2 diabetes.

4. Ethnicity

Statistics show that in the USA, African Americans develop and die from cancer more than other racial groups. This may be due to a variety of factors, such as socioeconomic status as well as genetic factors.

5. Smoking

Tobacco smoking causes over 70% of all respiratory cancers and is a strong risk factor in many other cancers. In addition, studies suggest that smoking is an independent risk factor for developing Type 2 diabetes and we know smoking will always worsen the complications of diabetes.

6. Alcohol

Even if alcohol is consumed moderately, it’s associated with an increased risk of cancers such as mouth, throat, gastrointestinal and breast. Moderate alcohol consumption may be protective against the development of diabetes, but excess alcohol is a diabetes risk.

7. Sedentary lifestyle

There is a definite link between lack of physical activity and the risk of Type 2 diabetes and cancer.

Do diabetes treatments influence the incidence of cancer and cancer prognosis?

Good glucose control lowers the risk of complications and possibly cancer too. The influence of the various drug treatments are as follows:

1. Metformin

At diagnosis all people with Type 2 diabetes are prescribed metformin and this is continued lifelong unless it can’t be tolerated, or kidney function drops below a certain threshold.

Metformin reduces circulating levels of glucose and insulin by reducing the production of glucose in the liver. Studies have shown that metformin inhibits the growth and proliferation of cancer cell lines.

Other research has demonstrated that metformin can selectively kill certain cancer stem cells, improving the effectiveness of the anticancer regimen. This has been particularly described in breast cancer.

There is significant evidence to show that PLWD who are on metformin are less likely to get cancer than PLWD that don’t take metformin. Additional observational data also suggests that PLWD taking metformin who do develop cancer are more likely to go into remission.

Metformin is sometimes used as an adjuvant treatment in a cancer regimen even in people without diabetes, particularly with breast cancer therapy.

2. Thiazolidinediones

These are medications that work in the liver to treat insulin resistance. Pioglitazone is the only one available in SA. Results of studies are conflicting whether these drugs decrease, increase or do not affect cancer risk.

3. Sulfonylureas

There is very little data to suggest any benefit or risk in this group of medications.

4. Incretins

These are the injectables liraglutide, semaglutide, and dulaglutide. They bind to the glucagon like peptide-1 (GLP1) receptor which results in lower glucose levels and weight loss.

Liraglutide showed an increased risk of medullary thyroid cancer in rats. The risk of this cancer remains a black box warning. A study published in the British Medical Journal in April 2024 calculated that there was very little increase in risk for thyroid cancer in patients using GLP1 receptor agonists. They report this would be 0.36 excess cancers per 10 000 person-years which compares favourably to a background incidence of cancer in diabetes of 1.46 per 10 000 person-years. However, if there is a history of thyroid cancer or a family history of thyroid cancer, the PLWD may still be advised not to use this therapy.

5. Insulin

As mentioned above, we know that high levels of insulin can be implicated in causing cancer. Naturally, PLWD who must inject insulin to treat their diabetes will be concerned. To date, there is no definite proof that insulin as a therapy causes cancer. However, people living with Type 2 diabetes who are using insulin will often have other risks as well: longer duration of diabetes with insulin resistance, obesity, older age.

One study also indicated a greater risk of developing cancer with higher doses of insulin. It’s critical to acknowledge that cancer cells in a person living with Type 2 diabetes may have spent years being exposed to abnormally high endogenous insulin due to insulin resistance. Thus, it’s difficult to blame the newly injected exogenous insulin to be the cause of any cancer.

How to lower cancer risk if you have diabetes

The most common cancers associated with Type 2 diabetes are breast, colon and prostate. However, as noted previously, if the PLWD also has an increased body weight there are many more cancers associated with obesity. Two main strategies are important: prevention and screening.

Prevention

There is always benefit in trying to improve the modifiable factors of lifestyle

• Weight

Keeping body weight to normal or near normal is protective. This will lower insulin resistance while improving glucose control. In addition, weight loss has been shown to decrease cancer risk.

• Diet

Having a diet that supports weight management is essential. There is also value in choosing foods that lower inflammation and have less direct carcinogens. The World Health Organization recommends avoiding processed meat as much as possible. Processed meats are prepared by smoking, curing, salting or adding chemicals (ham, bacon, pastrami, hot dogs, sandwich meat). Red meat should be restricted to 500g weekly. In fact, a plant-based diet is less inflammatory and lowers cancer risk.

• Physical activity

Recommended activity is 150 minutes weekly ideally spread out over five days. This can be aerobic and resistance exercise.

• Stop smoking

The connection between smoking and cancer has been established since 1963! Stop smoking!

• Reduce alcohol

A woman can have 1 – 2 units daily and a man 2 – 3 units daily. One unit of alcohol is 340ml beer/cider; 120ml wine; 25ml spirits.

Screening

These recommendations are for the general population but if you are at higher risk for a certain cancer (family history, radiation exposure, etc.), then please chat to your doctor about your screening schedule.

BREAST – Start age 40 years with mammograms and generally every two years thereafter unless at higher risk. Monthly self-examination is also important.

CERVICAL – Screening starts age 25 years. A Pap smear can be done every three years, but the newer human papillomavirus (HPV) screening can be done every five years.

PROSTATE – Age 40 is the recommended screening age in black men and 45 years in other races with an annual PSA blood test. Any abnormality or change in this would prompt further testing by a urologist.

COLON – Start age 50 years with a stool sample to test for occult blood. Every 10 years a colonoscopy can be done.

SKIN – Be aware of changes in your own skin. An annual check with your doctor or dermatologist is valuable.

LUNG – In smokers age 55 – 80 years (and this is even for ex-smokers), consider having a CT chest annually.

Closing remarks

There is a link between diabetes and cancer. However, scientists from Mount Sinai in the USA, who looked at diabetes and pancreatic cancer, are still not clear about what comes first – the cancer or the diabetes.

What we do know is that high blood glucose will increase cancer cell metabolism and growth so good glucose control is essential. We also know that certain medications are protective, especially metformin.

With a healthy lifestyle and avoidance of other risk factors, as well as regular cancer screenings, it should be possible for PLWD to lower the risk of a cancer diagnosis.

References

1. Edward Giovannucci, David M. Harlan, Michael C. Archer, Richard M. Bergenstal, Susan M. Gapstur, Laurel A. Habel, Michael Pollak, Judith G. Regensteiner, Douglas Yee; Diabetes and Cancer: A consensus report. Diabetes Care 1 July 2010; 33 (7): 1674–1685.
2. Wang L, Xu R, Kaelber DC, Berger NA. Glucagon-Like Peptide 1 Receptor Agonists and 13 Obesity-Associated Cancers in Patients With Type 2 Diabetes. JAMA Netw Open. 2024;7(7):e2421305
3. https://www.discovery.co.za/corporate/health-ovarian-cancer-screening-and-prevention
4. https://www.cedars-sinai.org/blog/link-between-pancreatic-cancer-and-diabetes.html

Dr Angela Murphy qualified as a specialist physician in 2000 and joined the Department of Endocrinology and Metabolism at Charlotte Maxeke Johannesburg Academic Hospital. Currently she sees patients at Sunward Park Medical Centre. She retains a special interest in endocrinology and a large part of her practice is diabetes and obesity. She is a member of the Society of Endocrinology and Metabolism of South Africa and the National Osteoporosis Foundation and is actively involved in diabetes patient education. Living with diabetes in the family for 17 years has shown her that knowledge is power. Basic principles in diabetes must always be applied but people living with diabetes should also be introduced to innovations in treatment and technology which may help their diabetes journey.

Header image by FreePik

– OTHER INTERESTING READS –

Christine Manga, a diabetes nurse educator, unpacks what steroid-induced diabetes is.

Listen to this article below or wherever you get your podcasts or visit our playlist.

Can steroids cause diabetes? The short answer is yes. There are a few terms used to describe this: steroid-induced diabetes, glucocorticoid induced hyperglycaemia, and new-onset diabetes after transplant (NODAT).

What are steroids?

Let’s delve into what steroids are, what they are used for, how they work, how they increase glucose levels and more.

The two main types of steroids we are going to discuss are glucocorticoid steroids (GCs) and androgenic/anabolic steroids which are hormones. Our focus will be on glucocorticoid steroids. These hormones are produced naturally in the body.

Testosterone is the naturally occurring androgenic steroid produced mainly in the testes in men and in a very small amount in women in the ovaries. This stimulates the development of male characteristics, such as more bodily hair, especially on the face, chest and underarms, deep voice, larger and stronger muscles. Mood, energy and sexual drive are also partially regulated by testosterone.

Cortisol is produced in the adrenal glands. It’s stimulated in many responses. It regulates our stress response to both physical and psychological stimuli, assists in metabolism, blood pressure and blood glucose regulation, suppresses inflammation (the body’s immune response), and plays a role in the circadian (sleep–wake) cycle as well as many other bodily functions. Testosterone and cortisol are usually produced at optimal levels in the body.

These steroids are also produced synthetically to mimic the effects of those made by the body.

Why are synthetic steroids used and how do they work?

Personal use

Often used by bodybuilders, anabolic steroids, a testosterone-mimicking steroid is usually used by people wanting to bulk up muscle and become stronger in a short period of time. There are also medical reasons to use these.

Medical use

GCs are used to suppress the body’s natural immune response, act as anti-inflammatory and anti-allergic drugs. People using GCs are therefore immunosuppressed. Conditions that would require these medications are usually autoimmune (a disease where the body’s immune system attacks its own healthy cells causing damage to the body). Some examples include: lupus, rheumatoid arthritis, celiac disease, psoriatic eczema, ulcerative colitis, adrenal insufficiency (Addison’s), and multiple sclerosis. These conditions require life-long GCs.

There are other inflammatory conditions that require GCs that are not autoimmune, such as asthma, severe bronchitis, severe allergic reactions. The GCs would be prescribed for acute and not chronic use.

Some people with cancer use them to assist in reducing chemotherapy side effects. People who have undergone an organ transplant will be prescribed life-long GCs to prevent the body from rejecting the new organ by reducing the body’s immune response to the foreign body.

These recipients who do develop diabetes are known as having NODAT.

Steroid preparations

GCs are taken in different preparations: tablets, intravenously, intramuscular injection, inhaled, and applied as a topical (skin) treatment.

Most inhaled and topical applications don’t affect glucose regulation, but long-term use would require monitoring. GCs are divided into three types, short-, intermediate- and long-acting.

How do glucocorticoid steroids affect blood glucose levels?

These steroids are called glucocortico steroids because of their effect on blood glucose levels. GCs make the liver less sensitive to insulin and signals the liver to produce more glucose called gluconeogenesis, even though the pancreas is producing and secreting insulin, albeit less.

Insulin production would normally inhibit gluconeogenesis. Reduced insulin sensitivity means that although the insulin required to transport glucose into muscle and fat cells is there, it’s unable to do the job leaving the glucose in the bloodstream. CGs increase the effects of epinephrine and glucagon which in turn increase glucose levels. These drugs often increase appetite and carbohydrate intake.

Risk factors for developing or worsening diabetes

Individuals who are overweight/obese, have a family history of diabetes, or have a history themselves of elevated glucose levels or prediabetes, and over the age of 50 are at a greater risk of developing steroid-induced diabetes.

Taking high doses for prolonged periods will increase the risk. People who already have diabetes will experience higher than usual glucose levels. People taking GCs are immune suppressed and are therefore also prone to developing other infections.

Other GCs effects on the body

Increased intra-ocular pressure causing glaucoma; this is important to monitor as people with diabetes are already predisposed to developing glaucoma, a leading cause of blindness. Weight gain, skin thinning, muscle weakness, and bone loss can occur. Fat redistribution takes place with long-term GCs use, resulting in fat accumulation around the abdomen and face known as moon face. Mood may be affected too.

How to mitigate the effects of glucocorticoid steroid use

If you already have diabetes, you may need to augment your oral medication with insulin. If already on insulin, dose adjustments will be necessary.

People who did not have diabetes to start will commence on oral medication.

After discontinuation of the GCs, some people will revert to normal blood glucose levels and be able to stop the diabetes medication.

Good food choices, such as smaller portions of carbohydrates and more low GI foods, as well as physical exercise where possible will play a positive role.

Regular monitoring of glucose levels

It’s important to monitor blood glucose levels regularly whilst using GCs. This will assist in early diagnosis of diabetes and timely intervention. People with existing diabetes will need to increase testing frequency. Even after discontinuation of GCs, which must be tapered, three-monthly Hba1c screening is advised.

Christine Manga (Post Grad Dip Diabetes and Msc Diabetes) is a professional nurse and a diabetes nurse educator. She has worked with Dr Angela Murphy at CDE Centre, Sunward Park since 2012.

Header image by FreePik

– OTHER INTERESTING READS –

Here are six essential tips to love your feet and always be foot ready. 

If you have diabetes, you know that your feet can be severely affected by it. The two biggest foot concerns for people with diabetes are peripheral vascular disease and neuropathy.

Peripheral vascular disease (PAD) can constrict the arteries that transport blood to the legs and feet. This lack of blood flow increases the risk of developing ulcers (open sores) and infections.

Neuropathy occurs when high blood glucose harms your nerves and blood vessels, making your feet and legs less able to feel temperature changes or pain. You might not notice if you get a small cut or sore. With reduced blood flow, these injuries can also heal much more slowly. If they go untreated, they can become infected, which could lead to further complications.

Those with diabetes also experience an increased risk of athlete’s foot, toenail fungus, blisters, bunions, ingrown toenails, and plantar warts.

Foot ready tips 

Wash and dry your feet daily

Practise good foot care by keeping your feet clean, using mild soap and warm water. Pat your skin dry; do not rub, and ensure your feet are thoroughly dried. After washing, apply lotion or petroleum jelly to the soles of your feet to prevent cracking. 

Check your feet every day

Take a good look at the tops and bottoms of your feet every day. Check your toes, heels, and in between your toes for any blisters, corns, calluses, ingrown nails, cuts, scratches, bruises, or sores. Don’t forget to watch for any signs of fungus between your toes.

Take care of your toenails

Trim your toenails carefully with stainless steel toe clippers or sharp nail scissors. Cut them straight across and smooth the edges with a nail file. Never cut the cuticles (the thin layer of skin that forms at the base of the toenail, where the nail meets the skin), and don’t use sharp objects to clean under your nails. To soften rough heels, use a pumice stone, but avoid scrubbing too hard.

Protect your feet while exercising

Exercise regularly to keep your blood flow healthy. Aim to move your body for at least 30 minutes a day. Walk and work out in comfortable shoes. While aerobic and resistance training are typically suggested for diabetes, ask your doctor which activity is best for you.

Always wear shoes 

Even though warm weather might make you want to go barefoot, your feet need the protection shoes provide. Avoid wearing shoes with high heels or pointed toes, and steer clear of styles that expose your toes or heels, like open-toed shoes, flip-flops, or sandals.

Follow your doctor’s advice if they recommend special footwear, and replace shoes when they show wear, such as uneven heels or damaged lining.

Try diabetes-friendly socks

Switching up your socks every day is a must. Choose natural fabrics like cotton, wool, or blends of the two. These materials let your feet breathe and keep things comfy. Avoid socks with rough seams that could rub and cause blisters and anything too tight that might restrict your circulation.

If you want to go the extra mile to be foot ready, try diabetes-friendly socks. They’re specially made to boost blood flow and keep your feet feeling their best.

This article is attributed to Affinity Health. 

Header image by FreePik

– OTHER INTERESTING READS –