Severe hyperglycemia can become a hospital-level emergency within hours. This checklist walks you through exactly what to do at home, what never to do, and the precise moment to stop managing it yourself and call 911.
If blood sugar is high and the person is alert and not vomiting, drink water, check ketones, take only your prescribed correction dose of insulin, and recheck every 2 hours. If there is vomiting, confusion, fruity breath, rapid breathing, or severe abdominal pain, call 911 — DKA and HHS need IV fluids and insulin in a hospital, not at home.
- The 10-point emergency checklist
- What actually counts as a blood sugar emergency
- The home protocol, step by step
- Five mistakes that make a hyperglycemic emergency worse
- What doing it right looks like
- Call 911 — not the internet — if any of these are present
- What happens in the emergency department
- Prep now: the sick-day kit that prevents most emergencies
- Frequently asked questions
The 10-Point Emergency Checklist
This checklist applies to a conscious adult or child with a high blood glucose reading who can swallow and is not vomiting. If the person is unresponsive, seizing, or unable to hold fluids down, skip the checklist entirely and call emergency services.
The person cannot be woken, is breathing deeply and rapidly, is vomiting repeatedly, has a blood ketone level above 1.5 mmol/L, or has glucose above 400 mg/dL that is still climbing. These are hospital emergencies. Call emergency services and do not attempt home correction.
What Actually Counts as a Blood Sugar Emergency
Not every high reading is an emergency, and the distinction matters because the wrong response wastes precious time. Two specific syndromes define the true emergencies: diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS). Both are diagnosed with lab criteria, not with a single meter reading.[1]
DKA develops when there is not enough insulin to move glucose into cells, so the body burns fat for fuel and produces acidic ketone bodies. The American Diabetes Association defines it by a blood glucose typically above 250 mg/dL, arterial pH below 7.30, bicarbonate below 18 mEq/L, and moderate or large ketones in blood or urine.[1] It can develop within 24 hours and is most common in type 1 diabetes, though it occurs in type 2 diabetes too.
HHS is the opposite end of the spectrum: glucose is far higher — often above 600 mg/dL — with profound dehydration and extremely concentrated blood, but minimal ketones and a pH that stays near normal.[1] It typically affects older adults with type 2 diabetes and develops over days to weeks. HHS carries a substantially higher death rate than DKA, largely because people wait longer before seeking care.
| Situation | Typical glucose | Ketones | What it looks like | Correct action |
|---|---|---|---|---|
| High but stable | 180–250 mg/dL | Negative or trace | Thirsty, tired, otherwise fine | Water, prescribed correction dose, recheck in 2 hours |
| Marked hyperglycemia | 250–400 mg/dL | Negative | Very thirsty, urinating often, blurred vision | Home protocol, contact clinician if not falling after 2 doses |
| Suspected DKA | Usually >250 mg/dL (can be lower on SGLT2 inhibitors) | Moderate to large | Nausea, vomiting, belly pain, fruity breath | Emergency department now |
| HHS | Often >600 mg/dL | Negative or trace | Confusion, extreme drowsiness, severe dehydration | Call 911 |
| Hypoglycemia (for contrast) | Below 70 mg/dL | Not relevant | Shaking, sweating, confusion | 15 g fast-acting carbohydrate, recheck in 15 minutes |
Drugs such as empagliflozin, dapagliflozin, and canagliflozin can cause ketoacidosis at glucose levels below 250 mg/dL — sometimes even under 200 mg/dL. The FDA has issued a safety communication specifically about this risk.[3] If you take one of these medications and feel nauseated, short of breath, or generally unwell, check ketones regardless of what your glucose meter says.
The Home Protocol, Step by Step
When glucose is elevated but there are no red flags, a structured protocol keeps you from panicking or overcorrecting. Work through the steps in order and write down the time of every action.
People with diabetes should have a written sick-day management plan that includes instructions for insulin adjustment, frequency of glucose and ketone monitoring, hydration targets, and clear thresholds for contacting the care team or going to the emergency department. Such plans should be reviewed at least annually.[1]
Five Mistakes That Make a Hyperglycemic Emergency Worse
Most preventable escalations trace back to one of these five errors. Each one is common, each one is understandable under stress, and each one can turn a manageable high into a hospital admission.
1. Insulin stacking. Taking another dose 30 minutes after the first because "nothing is happening yet." Rapid-acting insulin peaks at 60–90 minutes but keeps working for 4 hours. Stacking doses causes severe, delayed hypoglycemia — which is more immediately dangerous than the high you were treating.
2. Exercising to burn off the sugar. When insulin is insufficient, exercise triggers stress hormones that push glucose even higher. If ketones are present, exercise accelerates ketoacidosis.
3. Skipping basal insulin because you're not eating. Fasting does not eliminate the need for background insulin. The body continues releasing glucose from the liver regardless of intake.
4. Treating the symptoms with sugar. Juice, regular soda, sweet tea, and electrolyte sports drinks are frequently handed to a dehydrated person with high glucose. Plain water or sugar-free electrolyte solutions are the correct choice here.
5. Trusting an unregulated supplement. Products marketed as "blood sugar support" or "glucose detox" have no role in acute management and can delay real treatment or interact unpredictably with prescription medication.
One more error deserves its own mention: waiting. Many people with DKA arrive at the hospital after 12 or more hours of symptoms because the early signs — thirst, nausea, and fatigue — feel manageable. DKA can progress from first symptom to a life-threatening state in under 24 hours, and the earlier treatment begins, the shorter and simpler the hospital course tends to be.
What Doing It Right Looks Like
Effective emergency hyperglycemia management is boring by design. It looks like a written timeline, a glass of water, a single measured insulin dose, and a phone call when the numbers don't move.
- You have the time, reading, ketone result, and dose written down for every intervention.
- You are giving water steadily rather than large volumes all at once.
- You waited the full 2 hours before rechecking, rather than testing every 15 minutes.
- You gave exactly the correction dose your plan specifies — no more, no less — and you did not repeat it early.
- You kept long-acting insulin on its normal schedule.
- You called your clinician or an advice line before things got out of hand, rather than after.
- You set a clear decision point in advance: "If glucose is still over 300 in two hours, I'm calling."
There is also a psychological component worth naming. Hyperglycemia triggers anxiety, and anxiety drives the urge to do something — anything — immediately. The protocol works precisely because it replaces that urge with timed, measured actions. Checking glucose every 15 minutes and dosing repeatedly feels productive but is one of the fastest routes to a hypoglycemic emergency.
"The single most useful thing a person with diabetes can bring to an emergency is a written sick-day plan with their clinician's name, their correction factor, and a specific glucose number that means 'go to the hospital now.'"
— Standard sick-day planning guidance, ADA Standards of Care in Diabetes—2026
Call 911 — Not the Internet — If Any of These Are Present
Emergency services exist because some hyperglycemic states cannot be safely reversed at home. Intravenous fluids, an insulin drip, and continuous electrolyte monitoring are hospital interventions. Calling for help early is not an overreaction; it is the correct clinical decision.
Do not give anything by mouth — no water, no insulin, no glucose gel. Place them on their side in the recovery position to protect the airway, call emergency services, and stay with them until help arrives. If you have injectable glucagon and cannot confirm the glucose level, tell the dispatcher so they can advise you.
What Happens in the Emergency Department
Knowing what to expect removes some of the fear from the decision to go. The initial evaluation for a suspected hyperglycemic emergency is fast and protocol-driven, and treatment typically begins within the first hour.
The first step is a set of labs: blood glucose, a basic metabolic panel for electrolytes and bicarbonate, a blood gas for pH, serum ketones, and often a serum osmolality. These are the exact values the ADA criteria are built around.[1] Clinicians also look for the trigger — infection, missed insulin, a failing insulin pump or occlusion, a heart attack, or a new medication such as a steroid or an SGLT2 inhibitor.
Treatment follows a predictable sequence: intravenous fluid resuscitation with normal saline or a balanced crystalloid, an intravenous insulin infusion, and careful potassium replacement. Potassium is the step people underestimate. Insulin drives potassium into cells, and total-body potassium is already depleted in DKA even when the serum level looks normal or high. That is why insulin infusions are paired with frequent electrolyte checks, typically every 2 to 4 hours during the acute phase.
Bicarbonate is generally reserved for severe acidosis, and phosphate replacement is considered in specific cases. Once glucose falls to around 200–250 mg/dL, intravenous fluids are switched to include dextrose so the insulin infusion can continue clearing ketones without causing hypoglycemia.
Prep Now: The Sick-Day Kit That Prevents Most Emergencies
The best time to prepare for a blood sugar emergency is when your blood sugar is normal. A well-stocked kit and a written plan convert a potentially chaotic night into a series of routine steps.
Assemble a physical kit that stays in one place — a labeled box, a drawer, or a bag that travels with you. Include ketone test strips (blood or urine, with unexpired strips), a spare glucose meter with extra lancets, an extra supply of both rapid-acting and long-acting insulin, a backup insulin pen or syringes, and a copy of your written sick-day plan with your clinician's after-hours phone number. Add sugar-free electrolyte powder, a thermometer, and a small notebook for logging readings.
The written plan itself is the highest-value item, and the ADA recommends every person with diabetes have one that is reviewed at least yearly.[1] It should specify your personal correction factor, how much to adjust basal insulin when you are sick, how often to check glucose and ketones, and the exact glucose or ketone number at which you should go to the emergency department. Vague plans fail under stress; specific numbers work.
Finally, make sure the people around you know where the kit is and how to use the plan. A spouse, roommate, or adult child who can read your correction factor off a page and call the right number is a genuine safety asset. Most hyperglycemic emergencies happen at home, at night, or on a weekend — precisely when the clinic is closed and the people nearby matter most.
Frequently Asked Questions
Can I bring my blood sugar down at home if it's over 300 mg/dL?
Sometimes, yes — provided you are alert, not vomiting, have no more than trace ketones, and have a prescribed correction dose you can follow. Take the correction dose, drink water steadily, keep basal insulin on schedule, and recheck in 2 hours. If glucose is still above 300 mg/dL after two appropriately spaced correction doses, or if ketones appear, stop managing at home and seek medical care.
How fast is it safe to bring blood sugar down?
Aim for a gradual decline of roughly 50–100 mg/dL per 2 hours. Faster corrections risk hypoglycemia, which can be more immediately dangerous than the high you were treating, and rapid shifts in fluid balance can worsen cerebral edema — particularly in children. Slow and steady is the clinical target, not a rapid crash to normal.
Does drinking water actually lower blood sugar?
Water does not remove glucose directly, but it corrects the dehydration caused by high glucose and helps the kidneys clear excess glucose through urine. Rehydration also improves circulation and makes insulin work more effectively. Plain water — not juice, sweetened tea, or regular sports drinks — is the right choice during hyperglycemia.
What if I have type 1 diabetes and my sugar is 400 with large ketones?
That combination is diabetic ketoacidosis until proven otherwise. Go to the emergency department now. Do not try to treat this at home with extra insulin injections — DKA requires intravenous fluids, an insulin infusion, and continuous electrolyte monitoring, and it can progress to a life-threatening state within hours. If you are alone and feel unwell, call emergency services rather than driving yourself.
Can SGLT2 inhibitors cause ketoacidosis with normal blood sugar?
Yes. The FDA has issued a drug safety communication warning that SGLT2 inhibitors can cause ketoacidosis at glucose levels below the usual DKA threshold, sometimes under 200 mg/dL.[3] If you take one of these medications and develop nausea, vomiting, shortness of breath, or unusual fatigue, check ketones even if your glucose reading looks acceptable — and seek care if ketones are elevated.
Should I take extra insulin when I'm sick even if I'm not eating?
Your basal insulin should continue unchanged or per your written sick-day plan, even during a fast. Additional rapid-acting correction doses depend on your glucose readings and your prescribed correction factor. Never increase your long-acting dose dramatically without clinician guidance, and never skip it entirely — insulin omission during illness is one of the leading triggers of DKA.
When should I test for ketones?
Check ketones whenever glucose is above 250 mg/dL, whenever you are sick or vomiting, whenever you have abdominal pain, and any time you take an SGLT2 inhibitor and feel unwell regardless of your glucose number. Also check if you use an insulin pump and your readings have been unexpectedly high for several hours — a blocked or dislodged cannula can cause rapid ketone development.
- True hyperglycemic emergencies are DKA and HHS; DKA requires glucose typically above 250 mg/dL with ketones and acidosis, while HHS often presents above 600 mg/dL with severe dehydration and minimal ketones.[1]
- At home, the correct sequence is water, ketone check, a single prescribed correction dose, continued basal insulin, and a recheck at 2 hours — never a second dose sooner.
- Vomiting, confusion, deep rapid breathing, fruity breath, severe abdominal pain, or ketones above 1.5 mmol/L all mean emergency services, not home management.
- SGLT2 inhibitors can trigger ketoacidosis at glucose levels under 250 mg/dL, so check ketones based on symptoms, not just the meter number.[3]
- Insulin stacking and exercising with ketones are the two most common self-inflicted complications during a hyperglycemic episode.
- Every person with diabetes should have a written sick-day plan with a specific correction factor and a specific "go to the hospital" number.[1]
- American Diabetes Association. Standards of Care in Diabetes—2026: Glycemic Goals and Hypoglycemia; Diabetes Care in the Hospital; and Hyperglycemic Crises in Adults With Diabetes. diabetes.org
- Centers for Disease Control and Prevention. National Diabetes Statistics Report. cdc.gov
- U.S. Food and Drug Administration. Drug Safety Communication: SGLT2 inhibitors for diabetes may result in a serious condition of too much acid in the blood (diabetic ketoacidosis). fda.gov
- NHS. Diabetic ketoacidosis — symptoms and when to get urgent help. nhs.uk
