Introduction

Sinusitis is an inflammation of the tissues in the sinuses, which are the places in your forehead, cheeks and nose (usually filled with air). Sinusitis is usually caused by a common cold; however, it can also be caused by other viruses, bacteria and fungi. Bacterial and viral infections and allergies can irritate the sinuses and lead them getting blocked and filled with fluid. It is commonly associated with facial pain, nasal congestion, and a fever, among other symptoms.¹ Inflammation causes the lining of the sinuses to swell up and to produce additional mucus, and the draining of the mucus is due to the swelling. Although it frequently goes away on its own or with little care, those who have long-term medical issues, such as diabetes, may experience more severe side effects. It's critical to understand how sinusitis interacts with these underlying disorders in order to diagnose it quickly, treat it effectively, and avoid complications, which we will discuss below. But first, let us understand more about sinusitis.

Understanding Sinusitis

There are different types of sinusitis, which are acute, subacute, chronic and recurrent sinusitis. Acute sinusitis is usually caused by viruses and has symptoms such as facial pain and nasal congestion, and typically lasts less than four weeks. Whereas for subacute sinusitis, symptoms can persist for 4 to 12 weeks, while chronic sinusitis is diagnosed when they continue for 12 weeks or more, often due to bacterial infections. Recurrent acute sinusitis symptoms come back 4 or more times in one year. 

Chronic sinusitis is a chronic inflammatory disorder of the nasal and prenasal mucosa, which includes the formation of nasal polyps.² Furthermore, sinus infections caused by fungus are more serious and are more likely in patients with weakened immune systems and underlying chronic conditions. Sinusitis may present with symptoms such as:¹

• Post-Nasal drip
• Runny nose with thick yellow/green mucus
• Facial pressure and pain/pressure in teeth
• Ear pressure/pain
• Halitosis or bad breath
• Cough
• Headache and fatigue 

Immunocompromised individuals are susceptible to viral, bacterial, parasitic and fungal infections, which can be overcome by healthy individuals. Such individuals are more susceptible to developing complications from common infections, as their immune system may not be capable of overcoming infections, leading to further complications over a period of time.³ 

Individuals with diabetes and other chronic conditions, like heart disease and inflammatory conditions like asthma, would be more susceptible to developing sinusitis infections. Individuals with chronic conditions often have weakened immune systems, making them more vulnerable to infections that can lead to chronic sinusitis.⁴ 

Sinusitis and Diabetes

People with diabetes may be more prone to sinus infections as a result of high blood glucose caused by the disease. Furthermore, if the condition is improperly managed, it can increase the risk of developing infections, which include infections related to those of the skin, oral cavity and sinuses. The risk of sinus infections becoming more common or severe in people with diabetes can be decreased by appropriately managing the condition and receiving the right treatment. This includes ensuring control of blood sugar levels, and this would also help to reduce the risk of developing complications related to diabetes, including renal failure, heart attack and stroke.⁵ 

Furthermore, individuals with diabetes can also be at risk for developing fungal sinus infections due to their increased risk of developing yeast infections like oral candida. This is because candida thrive in moist environments like the mouth and throat, and since diabetics have an accumulation of high glucose concentrations in these areas, fungi and microorganisms thrive.⁵ 

In addition to impairing immunity, diabetes can increase a person's vulnerability to infections.. Thus, as diabetes affects the immune system of individuals, it reduces their ability to cope with infections. Thus, preventive care along with effective monitoring of the disease is extremely crucial.⁵

Sinusitis and Respiratory Conditions (eg., Asthma and COPD)

Individuals with asthma are more likely to develop sinusitis infections due to the airways from the lungs to the nose, which are more sensitive to infections, allergens and other irritants. The term "unified airways disease" describes inflammation of both the upper and lower airways. Chronic obstructive pulmonary disease, or COPD, is similar to asthma, and patients with COPD can experience problems with inflammation affecting the upper airways and lungs.⁴

Sinusitis and Heart Disease

Coronary heart disease, or CHD involves coronary artery stenosis, which leads to coronary blood flow reduction as well as myocardial ischaemia. It is associated with the development of numerous other diseases. A retrospective cohort study investigated the correlation between CHD severity and chronic sinusitis of varying severity. The study conducted by Wu and his coworkers concluded that CHD is a comorbid medical disorder for patients with sinusitis. Since both of these conditions are inflammatory, an association could exist between these two conditions.²

The relationship between chronic inflammatory diseases and cardio-cerebrovascular disease has been noticed. Studies have also shown an association between chronic sinusitis and an increased risk for acute myocardial infarction and stroke. Even though the exact association is not fully revealed, one theory suggests that inflammation from the sinuses might spread to blood vessels in the brain because the sinuses are located very close to important structures like the carotid artery or the brain itself. Some other theories suggest that it could be due to inflammation-mediated emboli or spasms of cerebral arteries, adverse effects of medicines, or even complications which could occur due to sinus surgery.⁶

Impact of Sinusitis on Other Chronic Conditions

For patients with chronic kidney disease and sinusitis, there has been an association noted, including epistaxis, infections and olfactory dysfunction. However, there's a direct association between CKD and sinusitis. However, studies have provided insights into the underlying mechanisms.⁷  

Additionally, sinusitis can impact people with autoimmune disorders, such as those who have rheumatoid arthritis. It is suggested that medications like corticosteroids lead to further weakening of the immune system, making such individuals more susceptible to infections. Thus, sinusitis can also affect individuals with other chronic conditions such as CKD and other autoimmune diseases, and eventually, the immune system has a big role to play in coping with infections. 

Summary

Sinusitis is the inflammation of the sinus cavities. Even though many recover without complications, people who have chronic conditions such as diabetes, asthma, COPD, heart disease, and chronic kidney disease have a higher chance of sinusitis occurrence. Conditions like diabetes weaken the immune system and create a favourable environment for fungal growth, thereby increasing the risk of sinus infection. Similar to this, respiratory diseases like COPD and asthma make the sinuses more sensitive since they share airway pathways. It is essential that early intervention is taken in order to ensure that the increased risks of patients with chronic conditions like diabetes can be controlled. Early intervention and treatment would help to avoid any complications, especially for patients with chronic illnesses who are more susceptible to infections due to their weakened immune systems.