The appearance of “HI” on a blood glucose meter display signals that your blood sugar level is severely elevated, a condition known as extreme hyperglycemia. This reading indicates a serious medical situation requiring immediate attention. Understanding what “HI” signifies and how to respond is crucial for individuals managing diabetes. This article explains the meaning of the reading, details the necessary immediate steps, and reviews the common reasons for such extreme elevations.
Understanding the “HI” Threshold
The “HI” displayed on your glucose meter stands for “High,” signifying that the concentration of glucose in your blood has exceeded the device’s maximum measurable limit. This is not a specific numerical reading but an indicator that the level is dangerously high and beyond the meter’s capacity to quantify accurately. For most standard consumer blood glucose meters, the upper measurement threshold is 600 milligrams per deciliter (mg/dL).
Therefore, a “HI” reading means the blood glucose is at least 600 mg/dL, or 33.3 millimoles per liter (mmol/L), or possibly even higher. Some continuous glucose monitors (CGMs) may display “HI” at a slightly lower threshold, such as 400 or 500 mg/dL, depending on the manufacturer. This reading signifies a medical emergency because glucose levels this high can quickly lead to life-threatening complications like diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS).
Immediate Action Steps and Safety Protocols
The first step upon seeing a “HI” reading is to rule out a false measurement by performing an immediate re-test. Ensure your hands are clean and dry, use a new test strip, and confirm the meter is functioning correctly, potentially using a control solution. If the re-test confirms the “HI” reading, you must proceed with an established high blood sugar action plan.
A primary safety measure is to test for ketones, which are toxic acids produced when the body breaks down fat for energy due to a lack of insulin. The presence of moderate to large amounts of ketones alongside the high glucose level indicates impending or established DKA, requiring emergency medical care. Ketone testing can be done using urine dipsticks or a blood ketone meter for greater accuracy.
Follow your healthcare provider’s instructions for administering a corrective dose of fast-acting insulin, often referred to as a “sliding scale.” After taking the corrective insulin, recheck your blood glucose level approximately 30 minutes later to ensure the level is trending downward. Simultaneously, begin drinking extra sugar-free fluids, such as water, to combat the severe dehydration caused by high blood sugar as the body attempts to flush out excess glucose through urine.
If you have positive ketone results, are unable to keep fluids down due to nausea or vomiting, or if symptoms such as confusion, rapid breathing, or abdominal pain develop, seek emergency medical attention immediately. These symptoms suggest the development of DKA or HHS, which cannot be managed at home. If you are not experiencing severe symptoms, contact your doctor or diabetes care team immediately for guidance.
Underlying Reasons for Extreme Hyperglycemia
Extreme hyperglycemia that triggers a “HI” reading is caused by factors resulting in an insufficient amount of effective insulin in the body. Acute illness or infection is a common trigger because the body releases stress hormones to fight sickness. These hormones work against insulin, causing glucose levels to rise sharply. Conditions like the flu, a severe cold, or an infection often necessitate a temporary increase in insulin or medication to compensate for this hormonal surge.
A lapse in medication adherence is a primary cause, such as missing a scheduled dose of insulin or an oral diabetes medication. Temporary issues, like an insulin pump malfunction or using expired insulin, can also lead to a quick and dangerous rise in blood glucose. High levels of psychological or physical stress can contribute, as the resulting hormonal response elevates blood sugar even without changes in diet or medication.
Certain prescription medications, most notably steroid drugs used to treat inflammation, can dramatically increase blood glucose levels. Consuming a significantly larger amount of carbohydrates than expected, or miscalculating the appropriate insulin dose for a meal, can also push glucose past the meter’s limit. Identifying the specific cause is important for preventing future episodes once the immediate emergency has been resolved.