While diabetes is not a direct trigger for coughing, it significantly alters the body’s internal environment, creating multiple indirect pathways that increase the likelihood of a persistent cough. This connection is primarily driven by three factors: the immune system’s compromised ability to fight respiratory pathogens, specific physiological complications that physically irritate the airways, and the side effects of necessary medications. Understanding these mechanisms is the first step in effectively managing this frequently overlooked symptom.
Diabetes and Increased Susceptibility to Infection
Uncontrolled blood sugar, or hyperglycemia, is a major factor in reducing the body’s ability to defend against respiratory infections. Elevated glucose levels compromise the function of immune cells, making individuals with diabetes more vulnerable to bacterial and viral invaders. This impaired defense mechanism means that common infections, like bronchitis or the flu, are more likely to progress to severe issues such as pneumonia.
A primary area of concern is the function of neutrophils, a type of white blood cell responsible for destroying pathogens. In a hyperglycemic environment, neutrophils exhibit reduced phagocytic activity, making them less efficient at consuming bacteria. This dysfunction explains why people with diabetes experience higher rates of severe lung infections and often require prolonged recovery.
Physiological Complications That Trigger Coughing
Diabetes can cause chronic complications that physically irritate the throat and respiratory system, leading to a persistent cough. One such complication is diabetic neuropathy, which is nerve damage associated with prolonged high blood sugar. In some cases, this nerve damage can affect the vagus or laryngeal nerves, leading to laryngeal sensory neuropathy.
Damage to these sensory nerves results in an abnormal hypersensitivity of the cough reflex, causing a chronic, often non-productive cough. Symptoms often include throat clearing and a sensation of a lump in the throat. The irritated nerves misinterpret non-irritating stimuli, such as talking or breathing cold air, as a threat requiring a cough response. This mechanism is known as a neuropathic cough.
Another physiological link involves diabetes, gastroparesis, and gastroesophageal reflux disease (GERD). Diabetic neuropathy can slow the movement of food through the stomach, a condition called gastroparesis. This delayed emptying increases the likelihood of stomach acid and contents refluxing back up into the esophagus, leading to GERD.
When acid reflux reaches the upper airway, it can trigger a persistent cough in two ways. The reflux may cause direct microaspiration of tiny stomach particles into the lungs, physically irritating the tissue. Alternatively, the acid can stimulate the vagus nerve endings in the lower esophagus, triggering a reflex that causes the throat and airways to spasm, resulting in a chronic cough.
Medications That Induce A Persistent Cough
A common cause of a chronic cough in people with diabetes is a side effect from certain blood pressure medications. Angiotensin-Converting Enzyme (ACE) inhibitors are frequently prescribed to manage hypertension and protect the kidneys from diabetic nephropathy. However, 5% to 35% of patients taking these drugs develop a dry, hacking cough.
This cough is caused by ACE inhibitors blocking the enzyme that breaks down bradykinin in the lungs. When this process is inhibited, bradykinin accumulates and sensitizes the cough receptors in the airways. The resulting cough is non-productive, meaning it does not bring up mucus, and is not related to the medication dosage. The cough usually resolves within one to four weeks after discontinuing the ACE inhibitor, often by switching to an alternative medication class.
When to Consult a Healthcare Provider
A persistent cough in the context of diabetes requires evaluation by a healthcare provider to determine the underlying cause. If a cough lasts longer than one to two weeks, it warrants medical attention, especially if it interferes with sleep or daily activities. Given the increased risk of infection, any cough accompanied by a fever higher than 101 degrees Fahrenheit, shortness of breath, or chest pain requires urgent attention.
Other immediate warning signs include coughing up green or yellow mucus, which suggests a bacterial infection, or experiencing unexplained weight loss. Patients who have recently started a new blood pressure medication should also discuss their symptoms with their doctor, as a drug-induced cough is highly treatable by changing the prescription. Distinguishing between a simple cold and a diabetes-related complication is necessary to prevent a minor issue from escalating into a serious health event.