High blood sugar (hyperglycemia) is part of living with diabetes, and most highs are a manageable event, not an emergency. The skill is knowing which is which, because the same number can mean "correct it and recheck" for one person and "go to the ER now" for another, depending on ketones and how you feel. Here is the line.
When is a high manageable at home?
If you feel basically fine, ketones are negative or trace, and your blood sugar is high but not extreme, this is usually a home correction. Take your correction dose if your plan includes one (many insulin users have a correction factor from their doctor), drink water, skip additional carbs for now, and recheck in about two hours to confirm it is trending down. A walk can help a high come down only if ketones are absent. Highs after a big or carb-heavy meal, a missed dose, stress, or a bad sensor reading are common and usually resolve. What you are watching for is a high that will not come down after corrections, or any of the emergency signs above.
Why ketones are the number that matters
When there is not enough insulin to move sugar into cells, the body burns fat for fuel and produces ketones, which make the blood acidic. That is diabetic ketoacidosis (DKA), and it is the emergency behind most high-blood-sugar deaths in type 1. So if you have type 1 or take insulin, checking ketones (urine strips or a blood ketone meter) any time your blood sugar is over 240 or you feel unwell is the single most useful thing you can do. Trace or small ketones with a high usually means take insulin and fluids and recheck. Moderate or large ketones, or ketones with any vomiting, means call your team or go in. DKA can develop in hours, and the hospital bill that follows a DKA admission is its own fight, but the admission itself is not optional when the signs are there.
Sick-day rules: the highs that sneak up
- Keep taking insulin, even if you are eating less. Illness raises blood sugar through stress hormones, so your need for insulin can go up while your appetite goes down. Stopping insulin during sickness is the classic path into DKA.
- Check more often. Blood sugar every 2 to 4 hours and ketones every 4 to 6 hours while you are ill.
- Keep fluids going. Water when sugar is high, and sugar-containing fluids if you can't eat and your sugar is dropping. Dehydration makes everything worse.
- Know your call thresholds ahead of time. Ask your team now what readings or symptoms should trigger a call, so you are not guessing at 2am.
What about type 2 and the other high-sugar emergency?
People with type 2 diabetes get DKA less often, but they face a different crisis: hyperosmolar hyperglycemic state (HHS), where blood sugar climbs extremely high (often above 600) over days, usually during an illness, with heavy dehydration and worsening confusion. It is most common in older adults and it develops slowly enough to be missed until it is severe. The response is the same: severe thirst, very high readings, weakness, and confusion together are a 911 emergency, not a next-appointment issue.
How Kite handles this
Text Kite "my blood sugar is 380 and I feel nauseous" and it asks the questions that sort a manageable high from an emergency (ketones, symptoms, how long) and tells you the line for going in, so you are not deciding alone at 2am. It keeps your correction plan and your team's call thresholds in one place, and logs the highs worth reviewing at your next visit. It is not your doctor and never overrides an emergency sign. Text Kite to start.