Diabetes involves persistently elevated blood glucose levels (hyperglycemia). While this condition does not directly trigger the cough reflex, it initiates several indirect mechanisms and contributes to associated health issues that make coughing significantly more likely. People managing diabetes often experience respiratory problems that are more frequent, severe, and prolonged than in the general population. A persistent cough in this group should not be dismissed, as it can signal anything from a common infection to a serious, underlying complication.
How Diabetes Compromises Immune Function
Chronic hyperglycemia impairs the body’s natural defense mechanisms against respiratory pathogens. High blood sugar levels disrupt the function of various white blood cells, which are the immune system’s primary defense. Key immune cells in the lungs, such as dendritic cells, become functionally impaired.
These cells fail to properly recognize invaders and initiate the targeted immune response needed to clear an infection. This failure results in infections like bronchitis, influenza, or pneumonia becoming more frequent, severe, and difficult to control. The resulting inflammation and irritation of the airways directly cause the coughing reflex. People with diabetes face an increased risk of developing severe lung disease from common respiratory viruses. Effective management of blood glucose levels can help restore some immune cell function and lower the risk of severe respiratory tract infections.
Medications That Can Induce Coughing
A common non-infectious cause of chronic cough is a side effect of certain medications prescribed for related conditions. Angiotensin-Converting Enzyme (ACE) inhibitors are frequently prescribed to manage high blood pressure and protect the kidneys from diabetic nephropathy. ACE inhibitors are a well-known cause of a persistent, dry, hacking cough that can develop at any point after starting the medication.
The mechanism involves the drug preventing the breakdown of chemical messengers, namely bradykinin and substance P, in the airways. The accumulation of these peptides irritates the sensory nerves, triggering the cough reflex. This cough is typically non-productive, meaning it does not bring up mucus. If an ACE inhibitor is suspected, a healthcare provider may switch the patient to an alternative, such as an Angiotensin Receptor Blocker (ARB). ARBs work on a different part of the same system and do not typically cause the accumulation of the cough-inducing chemicals.
Associated Digestive and Cardiovascular Conditions
Gastroesophageal Reflux Disease (GERD)
Diabetes increases the risk of several internal complications that can cause a persistent cough, particularly those affecting the digestive system. Gastroesophageal Reflux Disease (GERD) is more prevalent in those with diabetes. This link is often due to diabetic neuropathy, which can damage the nerves controlling stomach muscle function, leading to a condition called gastroparesis. Gastroparesis slows stomach emptying, increasing the likelihood of acid reflux, where stomach contents back up into the esophagus. This acidic material can irritate the throat and upper airways, triggering a chronic, often non-productive cough, especially when lying down at night. The cough is essentially a reflex response to the irritation caused by the refluxate.
Congestive Heart Failure (CHF)
A more serious complication is the increased risk of Congestive Heart Failure (CHF), as diabetes is a major risk factor for heart disease. When the heart muscle weakens, it cannot pump blood effectively, causing blood to back up into the vessels of the lungs. This results in fluid leaking into the air sacs, a condition known as pulmonary edema. The presence of this excess fluid irritates the airways and triggers a persistent cough, which is the body’s attempt to clear the congestion. A cough caused by CHF is typically wet or productive. In advanced stages, it may be associated with pink or frothy sputum, indicating fluid and blood mixing in the air spaces. This type of cough often worsens when the person is lying flat due to the redistribution of fluid in the lungs.
Recognizing Warning Signs and Seeking Care
A persistent cough in a person with diabetes requires prompt medical evaluation to distinguish between a common infection and a serious complication. Certain symptoms accompanying a cough necessitate immediate consultation with a healthcare provider, as they can signal a life-threatening condition. A cough that lasts for more than two weeks, regardless of other symptoms, should always be evaluated to determine the underlying cause.
Immediate warning signs include:
- New or worsening shortness of breath, particularly difficulty breathing while resting or lying flat.
- A cough that produces pink, frothy, or blood-tinged sputum, which is a classic indicator of severe fluid buildup.
- Chest pain.
- Fever.
- A rapid or irregular heartbeat.