The coronavirus disease 2019 (COVID-19), caused by the SARS-CoV-2 virus, is primarily known as a respiratory illness, but its effects extend throughout the body. Evidence confirms a significant physiological link between this viral infection and the body’s ability to manage glucose metabolism. This relationship often leads to acute hyperglycemia, or high blood sugar, even in individuals with no previous history of diabetes. Understanding how the virus interferes with sugar regulation is important for managing the acute illness and assessing potential long-term health consequences.
Understanding How COVID-19 Affects Glucose Metabolism
The increase in blood sugar during a COVID-19 infection is driven by systemic stress, inflammation, and potential direct viral interference with glucose-regulating organs. When the body fights a severe infection, it mounts a strong inflammatory response, releasing immune signaling molecules like Interleukin-6 (IL-6) in excess. This systemic inflammation causes widespread insulin resistance, meaning the body’s cells no longer respond effectively to insulin, leaving glucose stranded in the bloodstream.
The body’s fight-or-flight response to illness also triggers a release of stress hormones, primarily cortisol and adrenaline. These hormones instruct the liver to produce more glucose while simultaneously reducing insulin effectiveness. This combination of increased glucose production and decreased glucose uptake results in elevated blood sugar levels.
Beyond these systemic effects, the SARS-CoV-2 virus may directly impair the pancreas, the organ responsible for producing insulin. The virus gains entry into human cells by binding to the Angiotensin-Converting Enzyme 2 (ACE2) receptor, which is expressed on the insulin-producing beta cells. Viral entry and the resulting local inflammation can potentially damage these beta cells, reducing the amount of insulin the body can produce.
Worsening Existing Diabetes and New Onset Cases
The metabolic disruptions caused by COVID-19 have two major clinical consequences: worsening control in people with pre-existing diabetes and the emergence of new-onset cases. For individuals already managing diabetes, the acute stress and inflammation can push blood sugar levels dangerously high, leading to severe complications. These complications include Diabetic Ketoacidosis (DKA) and Hyperosmolar Hyperglycemic State (HHS), which are life-threatening conditions requiring immediate medical attention.
A significant concern is the development of diabetes following the infection in previously non-diabetic individuals. Studies show that COVID-19 infection is associated with an increased risk of developing new-onset diabetes, with patients 1.75 times more likely to develop the condition compared to uninfected individuals. This can manifest as either Type 1 or Type 2 diabetes, suggesting the infection may unmask pre-existing risk or directly trigger the condition.
New-onset Type 2 diabetes is more prevalent than Type 1 following the infection, with cases developing within 1 to 12 months after the acute illness. While some cases may represent previously undiagnosed diabetes revealed by acute stress, evidence of persistent glucose dysregulation points to a direct role of the virus. The severity of the acute COVID-19 illness is often linked to the risk of new-onset diabetes, with these patients experiencing worse outcomes and higher mortality.
Immediate Management of High Blood Sugar During Infection
Managing blood sugar during an acute illness like COVID-19 requires heightened vigilance. Individuals with diabetes should increase blood glucose monitoring frequency to every two to four hours, especially if levels are high or symptoms are present. It is imperative to never stop taking prescribed insulin, even if appetite is reduced, as stress hormones will still elevate blood sugar.
Hydration is a primary concern; patients should drink plenty of non-caloric fluids, such as water or broth, at least half a cup every hour to prevent dehydration. If unable to eat solid food, consume small amounts of carbohydrates every one to two hours through liquids like juice or regular soda to prevent low blood sugar. Patients must consult their healthcare provider for specific guidance on adjusting insulin doses or temporarily stopping certain oral medications.
Monitoring for ketones is necessary for individuals with Type 1 diabetes and recommended for Type 2 patients when blood sugar is elevated, typically above 240 mg/dL. Warning signs for severe complications, such as DKA, include persistent vomiting, abdominal pain, rapid breathing with fruity-smelling breath, or confusion. The presence of moderate to high ketones, or an inability to keep liquids down, requires immediate emergency medical care.
Assessing Long-Term Risk After Recovery
Glucose dysregulation can continue long after the body has cleared the active SARS-CoV-2 infection, sometimes persisting as part of Long COVID. Even in non-diabetic individuals who experienced acute hyperglycemia, a significant proportion show persistently high blood glucose levels six months after recovery. This suggests the metabolic impact may not be temporary, potentially leading to a higher risk of developing chronic diabetes.
The risk of Long COVID symptoms, such as fatigue or brain fog, is also higher in people with poorly controlled Type 2 diabetes. Because of these lingering effects, follow-up screening is recommended for anyone who experienced severe hyperglycemia during the acute illness. A healthcare provider should perform an A1C test two to three months after recovery to assess the long-term status of glucose control.