High blood sugar, or hyperglycemia, occurs when the body has too little insulin or cannot use it properly, leading to an excess of glucose circulating in the bloodstream. While slightly elevated glucose levels are often managed at home with medication adjustments or lifestyle changes, severe high blood sugar requires immediate medical attention. Recognizing the signs that separate routine management from a medical emergency is crucial, as a delay in care can lead to life-threatening complications.
When High Blood Sugar Becomes Critical
The decision to seek emergency care for hyperglycemia often begins with a numerical reading. A blood glucose reading persistently above 250 milligrams per deciliter (mg/dL) is a serious warning sign, especially if it does not decrease after corrective insulin doses. Consistently elevated readings over a 24 to 48-hour period, even with mild symptoms, warrant an immediate call to a healthcare provider for guidance.
A single, extremely high reading is an urgent indicator that emergency intervention is necessary. If blood sugar registers 600 mg/dL or higher, or if the glucose meter displays “HI” because the value is too high to measure, a severe medical crisis is underway. These high levels are often associated with Hyperosmolar Hyperglycemic State (HHS), which is characterized by profound dehydration and confusion. Immediate presentation to the emergency room is required, even if severe physical symptoms have not yet developed.
Physical Symptoms That Demand Emergency Care
While blood sugar readings provide a quantitative measure, specific physical symptoms indicate a rapidly deteriorating situation. Excessive thirst (polydipsia) is a common sign of severe hyperglycemia, as the body attempts to replenish lost fluids. This is linked to frequent and excessive urination (polyuria), where the kidneys flush out excess glucose, pulling water along and quickly leading to severe dehydration.
A distinct combination of gastrointestinal symptoms suggests a medical emergency. This includes persistent nausea, repeated vomiting, or severe abdominal pain. The inability to keep fluids down accelerates dehydration and prevents the body from correcting the metabolic issue. When these symptoms are present alongside high blood sugar, seeking emergency care should not be delayed.
A unique physical sign is a fruity or acetone odor on the breath. This smell occurs because the body, lacking enough insulin to use glucose for energy, breaks down fat, producing acidic byproducts called ketones. The breath odor results from the body trying to excrete these ketones through the lungs. Other neurological signs, such as confusion, disorientation, or extreme fatigue and weakness, signal that the imbalance is affecting brain function. Rapid, deep, and labored breathing (Kussmaul respirations) is another sign the body is attempting to correct a dangerous buildup of acid in the blood.
Immediate Action and Understanding the Crisis
Once the decision to seek emergency care is made, several immediate steps can help prepare for the hospital visit. The most important action is to test for ketones using a urine or blood ketone meter, especially if the glucose reading is high and symptoms like nausea or vomiting are present. A high ketone reading confirms the body is in a state of ketosis, a precursor to a more dangerous acidic state. Reporting this high ketone level to emergency staff immediately upon arrival will expedite treatment.
While preparing to leave, attempt to consume small amounts of non-sugary fluids, such as water, if the person is conscious and not vomiting, to combat severe dehydration. It is also important to gather all relevant medical information to streamline the hospital intake process. This includes a list of current medications, the type of insulin used, the time of the last insulin dose, and any recent illness or infection that may have triggered the high blood sugar.
The medical emergency is typically diagnosed as either Diabetic Ketoacidosis (DKA) or Hyperosmolar Hyperglycemic State (HHS). DKA, more common in Type 1 diabetes, involves high glucose, high ketones, and blood acidity, requiring intravenous fluids, insulin, and electrolyte replacement for stabilization. HHS, more common in Type 2 diabetes, involves extremely high glucose levels and severe dehydration, often with minimal or no ketones. Both conditions are life-threatening and require immediate hospital stabilization to prevent complications like coma, brain swelling, or death.