Infections Can Cause Temporary High Blood Sugar Even Without Diabetes, Doctors Explain

Blood sugar levels can rise temporarily during an infection even in people who do not have diabetes. An illness triggers an immune response along with changes in hormones, metabolism, appetite, and activity levels. These shifts alter how the body produces and uses glucose, which can lead to higher readings than usual.

Medical Reasons

Dr Palleti Siva Karthik Reddy, a consultant physician at Elite Care Clinic, explains that an infection puts the body into a state of physical stress. Hormones like cortisol, adrenaline, and glucagon increase to meet the body's extra energy needs for fighting the illness. These hormones tell the liver to release more glucose into the blood while making tissues less sensitive to insulin. As a result, muscles and other tissues take in less sugar even if the pancreas produces normal amounts of insulin. This temporary condition is known as stress hyperglycaemia.

Testing and Recovery

There is no single blood glucose level that defines this condition because the increase depends on infection severity, medications, and a person's underlying health. A single high reading during an acute illness does not mean a person has diabetes. Once the person recovers, fasting glucose tests and HbA1c tests help determine if the high sugar was just temporary or a sign of a deeper problem. HbA1c works well because it shows average blood sugar over the past two to three months and is less affected by short illnesses. Blood sugar usually returns to normal as the stress response settles, but people should see a doctor if readings stay high or if they notice symptoms like extreme thirst, frequent urination, sudden weight loss, or heavy tiredness.