Diabetic Ketoacidosis (DKA) and Hyperosmolar Hyperglycemic State (HHS)¶

Diabetic Ketoacidosis (DKA) and Hyperosmolar Hyperglycemic State (HHS) are the two most dangerous acute hyperglycemic emergencies in diabetes care, capable of causing severe dehydration, circulatory shock, brain swelling (cerebral edema), coma, and death if not treated promptly with hospital intravenous fluids, electrolyte replacement, and insulin. While DKA develops rapidly over hours to a day when an absolute or severe lack of insulin forces the liver to burn fat into acidic ketones, HHS builds over several days to weeks (most often in older adults with Type 2 diabetes), driving blood sugar to extreme levels and draining up to 9 to 12 liters (2.4 to 3.2 gallons) of water from the body. Immediate recognition of warning signs like vomiting, abdominal pain, deep rapid breathing, or confusion, paired with home blood ketone testing and urgent emergency medical transport, saves lives.

Do this now¶

1. Call your local emergency number immediately if the person is confused, drowsy, breathing deeply and rapidly, vomiting repeatedly, or has blood ketones \(\ge 3.0\text{ mmol/L}\). Dial 911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom, or see all emergency numbers. Tell the dispatcher that the patient is in suspected Diabetic Ketoacidosis (DKA) or Hyperosmolar Hyperglycemic State (HHS) and needs hospital intravenous fluid resuscitation and electrolyte monitoring.
2. Test both fingerstick blood glucose and blood beta-hydroxybutyrate ketones immediately (if a meter is available). Do not rely on Continuous Glucose Monitor (CGM) sensor readings alone during severe dehydration or shock, as tissue fluid lags behind blood values. Write down the exact blood glucose number (or note if the meter reads "HI", which usually means above \(27.8\text{ to }33.3\text{ mmol/L}\) [\(500\text{ to }600\text{ mg/dL}\)]) and the exact blood ketone level in \(\text{mmol/L}\) (or urine ketone color).
3. Protect the airway by placing a drowsy, confused, or vomiting person on their side in the recovery position. Never give oral water, food, or pills to anyone who is lethargic, slurring their speech, confused, or actively vomiting, as they can easily inhale liquid into their lungs (aspiration pneumonia). If the person is fully awake, alert, and able to swallow without vomiting, encourage them to sip plain water or sugar-free electrolyte water (roughly 250 milliliters [8 fluid ounces] every 15 to 30 minutes for an adult) while awaiting medical care.
4. Check an insulin pump for tubing kinks or cannula failure, and NEVER stack massive subcutaneous insulin injections. If the patient uses an insulin pump and has high blood glucose with elevated ketones (\(\ge 1.5\text{ mmol/L}\)), assume the pump site has failed: do not give a correction bolus through the pump. Instead, follow their prescribed Sick Day Action Plan using a new subcutaneous insulin pen or syringe into a fresh skin site. Never give random or repeated ("stacked") large insulin injections to force down extreme blood sugar before paramedics arrive, as dropping blood glucose or blood osmolality too fast without prior intravenous saline and potassium causes fatal cerebral edema (brain swelling) and hypokalemic cardiac arrest.
5. Do NOT give acetaminophen (paracetamol), aspirin, or ibuprofen to a child or adolescent in suspected DKA, and avoid bicarbonate. Pediatric DKA carries a high risk of life-threatening brain swelling during the first 12 to 24 hours of treatment; keep the patient's head and shoulders slightly elevated at a 30-degree angle if they are awake, and let the hospital team manage temperature and acidosis carefully.
6. Gather all diabetes supplies, medication lists (especially SGLT2 inhibitors and steroids), and recent meter logs for the paramedics. Hand the ambulance crew the patient's glucose/ketone meter, insulin pens or pump model details, and a list of all daily medications so the emergency department can immediately initiate the correct intravenous saline and insulin infusion protocol.

Hyperglycemic crisis triage and ketone action decision tree¶

Use this clinical flowchart to evaluate high blood sugar, interpret blood or urine ketone readings, and decide between home sick-day management and immediate emergency hospital transport.

flowchart TD
    Start["Person with Known or Undiagnosed Diabetes Has:<br/>Blood Glucose >= 13.9 mmol/L (250 mg/dL)<br/>OR Any Illness / Nausea / Vomiting (Even if Glucose < 13.9 mmol/L on SGLT2i)"] --> RedFlags{"Are ANY Emergency Red Flags Present?<br/>1. Deep, rapid sighing breathing (Kussmaul respirations) or fruity breath<br/>2. Persistent vomiting or unable to keep fluids down for >2 to 4 hours<br/>3. Severe abdominal pain, confusion, extreme lethargy, or slurred speech<br/>4. Blood Ketones >= 3.0 mmol/L (or 'Large' urine ketones)<br/>5. Meter reads 'HI' (>33.3 mmol/L / 600 mg/dL) with extreme dehydration"}

    RedFlags -->|"YES: Any single red flag present"| CallEMS["IMMEDIATE HOSPITAL EMERGENCY (DKA or HHS):<br/>1. Call 911 / 112 / 999 Immediately<br/>2. If drowsy or vomiting: Recovery position & Nothing by Mouth (NPO)<br/>3. If fully alert & not vomiting: Small sips of plain water<br/>4. DO NOT stack large insulin doses before IV fluids/potassium"]

    RedFlags -->|"NO: Alert, breathing normally,<br/>not vomiting persistently"| CheckKetones{"Check Blood Ketones (Beta-Hydroxybutyrate)<br/>or Urine Ketone Strip"}

    CheckKetones -->|"Blood Ketones 1.5 to 2.9 mmol/L<br/>(Moderate Urine Ketones)"| ModKetones["Moderate Ketonemia (Impending DKA Warning):<br/>1. Contact diabetes team or urgent medical helpline immediately<br/>2. If on an insulin pump: Give rapid-acting correction via PEN/SYRINGE<br/>   into a fresh site and change entire pump infusion set<br/>3. Drink 250 mL (8 oz) sugar-free fluid every 30 to 60 minutes<br/>4. Re-check blood glucose and ketones in 2 hours (Go to ER if rising)"]

    CheckKetones -->|"Blood Ketones 0.6 to 1.4 mmol/L<br/>(Trace to Small Urine Ketones)"| MildKetones["Mild / Trace Ketonemia:<br/>1. Follow prescribed Sick Day Rules for extra rapid-acting insulin<br/>2. NEVER stop basal/long-acting insulin (even if not eating)<br/>3. Hydrate with water (or carb fluids if glucose < 10 mmol/L / 180 mg/dL)<br/>4. Re-check blood glucose and ketones every 2 to 4 hours"]

    CheckKetones -->|"Blood Ketones < 0.6 mmol/L (Normal)<br/>AND Glucose 13.9 to 22.2 mmol/L (250-400 mg/dL)"| NoKetones["Hyperglycemia Without Ketosis:<br/>- Take standard prescribed correction dose of rapid-acting insulin<br/>- Drink plenty of water and monitor for HHS dehydration signs<br/>- Seek medical care if glucose stays >16.7 mmol/L (300 mg/dL) for 2 checks"]

Understanding the pathophysiology: Why DKA and HHS develop and how they differ¶

Although both DKA and HHS arise from insufficient insulin action combined with surging stress hormones (glucagon, cortisol, epinephrine, and growth hormone), they follow two distinct biochemical pathways that explain why their symptoms, lab values, and immediate hospital risks differ.

1. Diabetic Ketoacidosis (DKA): Starvation in the midst of plenty¶

In Diabetic Ketoacidosis (DKA), there is a severe or absolute lack of circulating insulin. Without insulin, glucose stays trapped in the bloodstream and cannot enter muscle or fat cells for energy. Thinking the body is starving, the adrenal glands and pancreas release massive amounts of glucagon, adrenaline, and cortisol, which trigger two dangerous cascades: - Unchecked Lipolysis and Ketogenesis (Metabolic Acidosis): Adipose (fat) tissue breaks down rapidly into free fatty acids, which travel to the liver. The liver converts these fatty acids into three ketone bodies: beta-hydroxybutyrate (the primary circulating acid in DKA), acetoacetate, and acetone (which is exhaled by the lungs, producing a sweet "pear drop" or nail-polish-remover odor on the breath). These strong ketoacids overwhelm the blood's bicarbonate buffer system, dropping arterial blood \(\text{pH}\) below \(7.30\) (and below \(7.00\) in severe DKA). - Osmotic Diuresis and Electrolyte Depletion: Once blood glucose exceeds the kidney threshold of roughly \(10.0\text{ to }11.1\text{ mmol/L}\) (\(180\text{ to }200\text{ mg/dL}\)), glucose and ketones spill into the urine, dragging massive quantities of water, sodium, potassium, magnesium, and phosphate out of the body. An adult in DKA typically loses 5 to 7 liters (1.3 to 1.8 gallons) of body water (\(100\text{ mL/kg}\)) in 24 hours.

2. Hyperosmolar Hyperglycemic State (HHS): Extreme dehydration and thick blood¶

Hyperosmolar Hyperglycemic State (HHS) occurs predominantly in older adults with Type 2 diabetes (though it increasingly appears in adolescents and young adults with obesity and Type 2 diabetes). Unlike DKA, a person in HHS still produces just enough baseline pancreatic insulin to prevent fat breakdown (lipolysis) and ketone formation, but not enough insulin to stop the liver from pouring glucose into the blood or to move glucose into cells. - Because the patient does not become acidotic right away (no rapid vomiting or Kussmaul breathing in the first 24 hours), they do not feel acutely ill on Day 1. Instead, blood glucose climbs steadily over several days to 2 weeks, often reaching \(33.3\text{ to }66.6\text{ mmol/L}\) (\(600\text{ to }1,200\text{ mg/dL}\)). - This relentless osmotic diuresis drains 9 to 12 liters (2.4 to 3.2 gallons) of water (\(100\text{ to }200\text{ mL/kg}\), or up to 20 percent of total body water) from the patient's body. When illness, stroke, dementia, or nursing home immobility prevents the person from drinking enough water to keep up, blood osmolality climbs above \(320\text{ mOsm/kg}\). Water is sucked directly out of brain cells, causing profound lethargy, focal neurological deficits that mimic a stroke, seizures, coma, and arterial or venous blood clots (pulmonary embolism or myocardial infarction). Because patients are usually older and far more dehydrated, HHS carries a mortality rate of 10 to 20 percent, which is roughly 5 to 10 times higher than the mortality rate of DKA.

Head-to-head comparison: DKA vs. Euglycemic DKA vs. HHS vs. Hypoglycemia¶

Use this clinical diagnostic table (incorporating the latest 2024 Joint ADA / EASD / JBDS / AACE / DTS Consensus Report on Hyperglycemic Crises in Adults and ISPAD Pediatric Guidelines) to distinguish among diabetic emergencies:

Recognizing the warning signs and the SGLT2 inhibitor "Euglycemic DKA" trap¶

How DKA symptoms progress from Early Ketosis to Acidotic Collapse¶

1. Stage 1: Early Hyperglycemia and Ketonemia (Hours 1 to 6):
2. Unquenchable thirst (polydipsia), dry sticky mouth, and frequent trips to urinate (polyuria), including waking up multiple times overnight (or sudden bedwetting in a previously toilet-trained child).
3. Generalized muscle weakness, fatigue, blurred vision, and headache.
4. Blood glucose typically above \(13.9\text{ mmol/L}\) (\(250\text{ mg/dL}\)) with blood ketones rising between \(0.6\text{ and }1.5\text{ mmol/L}\).
5. Stage 2: Established Ketoacidosis (Hours 6 to 18):
6. Nausea, repeated vomiting, and severe abdominal pain: Acidemia and gastric stasis irritate the stomach lining and bowel wall. Once vomiting begins, the patient can no longer keep oral fluids down, accelerating dehydration into a downward spiral.
7. Kussmaul breathing ("air hunger"): Because the blood is dangerously acidic, the brain's respiratory center forces the lungs to take deep, rapid, sighing breaths to blow off acidic carbon dioxide (\(\text{CO}_2\)). Bystanders often mistake this deep sighing for a panic attack or asthma, even though the lungs sound clear.
8. Fruity "pear drop" or nail-polish-remover breath: Caused by volatile acetone gas evaporating out of the pulmonary capillaries.
9. Stage 3: Decompensated DKA and Shock (Hours 12 to 24+):
10. Sunken eyes, dry leathery tongue, poor skin turgor, fast weak pulse (\(> 120\text{ bpm}\)), falling blood pressure, confusion, inability to stay awake, cerebral edema, and cardiac arrest.

The Euglycemic DKA (euDKA) Trap: Why normal blood sugar can still hide lethal DKA¶

Over the past decade, Sodium-Glucose Cotransporter-2 (SGLT2) inhibitors, including empagliflozin (Jardiance), dapagliflozin (Farxiga/Forxiga), canagliflozin (Invokana), ertugliflozin (Steglatro), and sotagliflozin (Inpefa), have become widely prescribed for Type 2 diabetes, heart failure, and chronic kidney disease. These medications work by forcing the kidneys to dump 60 to 100 grams of glucose into the urine every day.

Because the kidneys are constantly clearing sugar out of the bloodstream into the urine, if a patient taking an SGLT2 inhibitor develops an infection, stops eating during a stomach virus, undergoes surgery, starts a low-carbohydrate/ketogenic diet, or reduces their insulin dose, their liver pours out acidic ketones while their fingerstick blood glucose stays deceptively normal or only mildly elevated (\(6.0\text{ to }11.0\text{ mmol/L}\) or \(110\text{ to }199\text{ mg/dL}\)).

Blood ketone testing vs. urine ketone strips: Why blood meters are superior in an emergency¶

When checking for DKA at home, capillary blood ketone meters (which measure beta-hydroxybutyrate [\(\beta\)-OHB] using a fingerstick strip, just like a glucose meter) are vastly more accurate and actionable than dip-and-read urine ketone strips (which only measure acetoacetate via the nitroprusside reaction):

1. Urine strips miss early DKA: During severe DKA, the liver produces up to 10 times more beta-hydroxybutyrate than acetoacetate. Because urine strips cannot detect beta-hydroxybutyrate at all, a urine strip may show only "trace" or "small" ketones when blood beta-hydroxybutyrate is already at a life-threatening \(3.5\text{ mmol/L}\).
2. Dehydration prevents urination: A severely dehydrated patient in DKA or HHS often cannot produce a urine sample for hours, whereas a fingerstick blood drop takes 10 seconds.
3. Urine strips create false alarms during recovery: As DKA resolves with treatment, beta-hydroxybutyrate converts back into acetoacetate and is flushed into the urine, making urine strips turn dark purple ("large") hours after the blood acidosis has actually cleared.

How to interpret blood beta-hydroxybutyrate (\(\beta\)-OHB) ketone numbers¶

Why you must NEVER stack massive insulin doses at home before hospital arrival¶

When a patient or family member sees a blood glucose meter reading \(28.0\text{ mmol/L}\) (\(500\text{ mg/dL}\)) or "HI", the instinct is often to inject a large dose of rapid-acting insulin (or repeat injections every 30 minutes) before going to the hospital. Giving unmeasured or stacked large insulin doses to a severely dehydrated patient in DKA or HHS outside a hospital is dangerous for three physiological reasons:

1. Severe dehydration blocks subcutaneous insulin absorption, then dumps it all at once¶

When a patient in DKA or HHS is dehydrated by 5 to 10 liters, blood vessels in the skin and subcutaneous fat constrict to preserve blood flow to the heart and brain. Multiple doses of rapid-acting insulin injected under the skin sit trapped in an unperfused subcutaneous depot. Once paramedics start intravenous saline and skin circulation returns, that pooled depot rushes into the bloodstream simultaneously, triggering severe hypoglycemic shock.

2. Driving potassium into cells before checking blood labs causes cardiac arrest¶

During DKA and HHS, osmotic diuresis drains massive quantities of potassium (\(\text{K}^+\)) into the urine. Although total body potassium is depleted, serum potassium initially looks normal because acidosis pushes potassium out of cells. Insulin forces potassium from the bloodstream back inside cells. If high-dose insulin is given before a hospital checks serum potassium (and before intravenous potassium chloride is added when \(\text{K}^+ < 5.0\text{ to }5.2\text{ mmol/L}\), or while insulin is held if \(\text{K}^+ < 3.5\text{ mmol/L}\)), blood potassium plummets within minutes, causing hypokalemic ventricular arrhythmias and cardiac arrest.

3. Dropping blood sugar too fast in HHS or Pediatric DKA causes Cerebral Edema and Vascular Collapse¶

• In HHS: High blood sugar is the main osmotic force holding water inside shrunken arteries, and brain cells have adapted over days to extreme osmolality (\(> 320\text{ mOsm/kg}\)). Hospital guidelines (UK JBDS and ADA/EASD 2024 consensus) state that the first hour of HHS treatment is \(0.9\%\) normal saline fluid resuscitation ALONE, which lowers blood sugar safely by \(2.8\text{ to }4.2\text{ mmol/L/hr}\) (\(50\text{ to }75\text{ mg/dL/hr}\)). Giving large insulin doses first sucks water out of arteries (causing circulatory collapse) and into brain cells, causing cerebral edema or osmotic demyelination.
• In Pediatric DKA: Children and adolescents are uniquely vulnerable to DKA-associated cerebral edema, which carries a 20 to 25 percent mortality rate. Lowering blood glucose too rapidly with insulin boluses (or giving intravenous sodium bicarbonate) dramatically increases the risk of fatal brain swelling.

Recognizing cerebral edema (brain swelling) in children and young adults¶

Watch every child, teenager, or young adult with DKA closely for signs of rising intracranial pressure (cerebral edema), which can begin before hospital arrival or 4 to 12 hours after treatment starts:

Red flag signs of cerebral edema (Immediate neurocritical emergency)¶

• New or worsening severe headache (especially after initial improvement).
• Sudden change in behavior: Unusual irritability, agitation, restlessness, or sudden drowsiness and inability to wake up.
• Slowing heart rate (bradycardia) paired with rising blood pressure (Cushing's triad): In a dehydrated DKA patient, heart rate is normally fast (\(110\text{ to }150\text{ bpm}\)). If a child's heart rate suddenly drops to \(60\text{ to }70\text{ bpm}\) while they become drowsy, suspect brain herniation immediately.
• Recurrent vomiting, unequal pupils, crossed eyes, abnormal posturing, or incontinence.
• Immediate action: Elevate the head of the bed to 30 degrees, keep the neck midline, and alert clinicians immediately so they can administer intravenous hypertonic \(3\%\) saline (\(3\text{ to }5\text{ mL/kg}\)) or mannitol (\(0.5\text{ to }1.0\text{ g/kg}\)).

Special emergency scenario: Insulin pump failure and the "Pen First" rule¶

Patients who use a continuous subcutaneous insulin infusion (CSII) insulin pump carry a unique vulnerability to rapid-onset DKA: - Unlike injection users who take daily long-acting basal insulin (glargine, degludec, or detemir) that stays active under the skin for 24 to 42 hours, an insulin pump contains ONLY rapid-acting insulin (lispro, aspart, or glulisine). - If the Teflon cannula under the skin kinks, dislodges, or blocks, circulating insulin drops to zero within 2 to 3 hours, and full-blown DKA can develop in 4 to 6 hours.

Step-by-step insulin pump ketone troubleshooting checklist¶

• Step 1: If blood glucose is \(\ge 13.9\text{ mmol/L}\) (\(250\text{ mg/dL}\)) and blood ketones are \(\ge 1.5\text{ mmol/L}\), assume the pump infusion site has failed, even without an occlusion alarm.
• Step 2: Do NOT deliver the correction bolus through the pump. Use a back-up disposable insulin pen or syringe to inject the prescribed rapid-acting correction dose into a fresh anatomical area.
• Step 3: Remove the old cannula/pod, inspect the skin for redness or leaking insulin odor, and insert a brand-new infusion set, reservoir, and fresh insulin in a new site.
• Step 4: Drink 250 to 500 milliliters (8 to 16 fluid ounces) of water and re-check blood glucose and ketones in 90 to 120 minutes. If ketones rise or vomiting begins, call 911 / 112 / 999 or go to the emergency room.

Golden rules of home Sick Day Management to prevent DKA and HHS¶

Over half of all hospital admissions for DKA and HHS are triggered by common illnesses (urinary tract infections, pneumonia, flu, COVID-19, or gastroenteritis) where a medication mistake occurs. Follow these five universal Sick Day Rules endorsed by the American Diabetes Association (ADA), Diabetes UK, and ISPAD:

1. Rule 1: NEVER stop taking your basal (long-acting) insulin, even if you are vomiting and eating zero food.
2. During fever or infection, stress hormones cause your liver to pour glucose and ketones into your blood continuously, even on an empty stomach. Stopping daily long-acting insulin (Lantus, Toujeo, Tresiba, Levemir) because you are not eating is a primary cause of DKA.
3. Rule 2: Check blood glucose and blood ketones every 2 to 4 hours around the clock (including overnight).
4. Do not rely solely on a Continuous Glucose Monitor (CGM) during dehydration, and always check ketones when blood sugar exceeds \(13.9\text{ mmol/L}\) (\(250\text{ mg/dL}\)) or whenever nauseated.
5. Rule 3: Drink 100 to 250 milliliters (3.5 to 8 fluid ounces) of fluid every 30 to 60 minutes, matching fluid type to your blood sugar.
6. Blood glucose above \(10.0\text{ to }11.1\text{ mmol/L}\) (\(180\text{ to }200\text{ mg/dL}\)): Drink sugar-free fluids (plain water, sugar-free electrolyte solutions, or clear salty broth).
7. Blood glucose below \(10.0\text{ mmol/L}\) (\(180\text{ mg/dL}\)) with nausea or elevated ketones: Sip carbohydrate-containing fluids (diluted fruit juice, regular oral rehydration solution, or ice pops) alongside prescribed sick-day insulin so the liver switches off ketone production.
8. Rule 4: Follow your endocrinologist's written Sick Day Supplemental Insulin Chart (typically 10% to 20% of Total Daily Dose).
9. Most clinics provide a chart based on your Total Daily Dose (TDD) of insulin. When blood glucose is elevated with mild-to-moderate ketones (\(0.6\text{ to }2.9\text{ mmol/L}\)), patients typically take an extra 10 to 20 percent of their TDD as rapid-acting insulin every 2 to 4 hours, guided by their written care plan.
10. Rule 5: Pause "SADMANS" medications during acute dehydration or vomiting.
11. Diabetes organizations use the "SADMANS" acronym for daily pills that must be temporarily paused during severe vomiting, diarrhea, or dehydration to prevent Euglycemic DKA, acute kidney injury, and lactic acidosis:
    • Sulfonylureas (glipizide, gliclazide, glimepiride: cause hypoglycemia if not eating)
    • ACE inhibitors (lisinopril, ramipril, enalapril: impair kidney filtration when dehydrated)
    • Diuretics / water pills (furosemide, hydrochlorothiazide: worsen dehydration and HHS)
    • Metformin (causes lactic acidosis if dehydrated kidneys cannot clear it)
    • Angiotensin Receptor Blockers / ARBs (losartan, valsartan, candesartan)
    • Non-steroidal anti-inflammatory drugs / NSAIDs (ibuprofen, naproxen: damage dehydrated kidneys)
    • SGLT2 inhibitors (empagliflozin, dapagliflozin, canagliflozin: trigger Euglycemic DKA)

Frequently asked questions¶

How can I tell the difference between low blood sugar (hypoglycemia) and high blood sugar (DKA or HHS) if I do not have a meter handy?¶

Hypoglycemia comes on within minutes and causes shaking, cold clammy sweat, pale skin, and sudden confusion. In contrast, DKA and HHS develop over hours to days and cause extreme thirst, frequent urination, dry flushed skin, vomiting, and deep rapid sighing breaths with fruity breath; if you cannot test blood sugar, treat for suspected hypoglycemia first because low blood sugar damages the brain within minutes, whereas 15 grams of sugar will not meaningfully worsen DKA or HHS.

Can someone who has never been diagnosed with diabetes suddenly develop DKA?¶

Yes, roughly 20 to 40 percent of children, teenagers, and young adults newly diagnosed with Type 1 diabetes only discover their condition when rushed to the emergency room in Diabetic Ketoacidosis. Always suspect new-onset Type 1 diabetes and DKA if a child or adult has had 1 to 3 weeks of unexplained weight loss, constant thirst, and frequent urination (or new bedwetting) followed by vomiting, abdominal pain, and deep rapid breathing.

Why is it dangerous for someone with an insulin pump to use the pump to fix high blood sugar and ketones?¶

Because an insulin pump uses only rapid-acting insulin and zero long-acting basal insulin, high blood sugar paired with elevated ketones (1.5 mmol/L or higher) usually means the cannula under the skin is kinked or blocked. Pushing a correction bolus through a blocked cannula delivers no insulin while wasting hours; inject the correction dose using a manual insulin pen or syringe into a fresh body site and change the entire pump infusion set.

What does it mean when a home blood glucose meter displays "HI" instead of a number?¶

On most consumer blood glucose meters, "HI" means capillary blood sugar exceeds the maximum readable limit of the device, typically above 27.8 to 33.3 mmol/L (500 to 600 mg/dL). A "HI" reading warns of Diabetic Ketoacidosis (DKA) or Hyperosmolar Hyperglycemic State (HHS); check blood ketones immediately, and if the person is confused, drowsy, vomiting, or has ketones above 1.5 to 3.0 mmol/L, call emergency medical services right away.

Sources checked¶

• American Diabetes Association (ADA, United States), European Association for the Study of Diabetes (EASD), Joint British Diabetes Societies for Inpatient Care (JBDS, United Kingdom), American Association of Clinical Endocrinology (AACE), and Diabetes Technology Society (DTS): Hyperglycemic Crises in Adults: A Consensus Report (Umpierrez et al., Diabetes Care / Diabetologia, 2024).
• International Society for Pediatric and Adolescent Diabetes (ISPAD): ISPAD Clinical Practice Consensus Guidelines: Diabetic Ketoacidosis and the Hyperglycemic Hyperosmolar State in Children and Adolescents (Glaser et al., Pediatric Diabetes).
• National Institute for Health and Care Excellence (NICE, United Kingdom): Type 1 Diabetes in Adults: Diagnosis and Management (NG17) and Diabetes (Type 1 and Type 2) in Children and Young People: Diagnosis and Management (NG18, including cerebral edema and fluid resuscitation protocols).
• Joint British Diabetes Societies for Inpatient Care (JBDS-IP, United Kingdom): The Management of Diabetic Ketoacidosis in Adults and The Management of the Hyperosmolar Hyperglycaemic State (HHS) in Adults.
• United States Food and Drug Administration (FDA), European Medicines Agency (EMA), and Diabetes Canada: Safety Alerts and Clinical Guidance on SGLT2 Inhibitor-Associated Euglycemic Diabetic Ketoacidosis and Sick Day Medication Management ("SADMANS" & "STOP DKA" Protocols).

Related guides¶

• Diabetic emergencies: hypoglycemia and immediate glucose rescue
• Shock recognition and first aid management
• Food poisoning, acute gastroenteritis, and dehydration
• Sepsis and septic shock recognition
• Stroke recognition (FAST) and emergency response