Beta-hydroxybutyrate (blood ketones)
The main ketone in the blood, made when the body burns fat instead of glucose for energy. Its key use is in diabetes: a high blood ketone level with high glucose signals diabetic ketoacidosis, a dangerous emergency, so it is measured to catch and monitor that.
What it measures
When the body cannot use glucose for energy — either because there is not enough insulin, or during fasting or a very low-carbohydrate diet — it breaks down fat instead, producing acidic molecules called ketones. Beta-hydroxybutyrate is the main ketone in the blood, and measuring it directly (a blood ketone test, on a finger-prick meter or lab sample) is more accurate and timely than the older urine ketone strips. Its most important use is in diabetes. In someone with diabetes (usually type 1) who becomes unwell, or whose glucose is high, a rising blood ketone level is the warning sign of diabetic ketoacidosis (DKA) — a serious emergency where ketones build up and turn the blood acidic. Home blood-ketone testing lets people with diabetes and their teams catch this early during illness. Ketones also rise, less dangerously, with prolonged fasting, a ketogenic diet, and heavy alcohol use.
What a high value can mean
- Diabetic ketoacidosis (DKA) — the critical use; high ketones with high glucose in someone with diabetes signals a medical emergency.
- Illness in a person with diabetes — infection or missed insulin can drive ketones up; a reason to check during sick days.
- Prolonged fasting or starvation — a milder rise.
- A ketogenic (very low-carb) diet — expected mild elevation.
- Heavy alcohol use (alcoholic ketoacidosis).
What a low value can mean
- Normal — the expected result; the body is using glucose for energy.
- A falling level during DKA treatment — shows the treatment is working.
When to discuss with a doctor
Blood ketone testing is most valuable for people with diabetes, especially type 1: during any illness, or when glucose is high, a blood ketone level that is rising or above the safe threshold is an early warning of diabetic ketoacidosis and, particularly if combined with vomiting, abdominal pain, rapid breathing or feeling very unwell, means seeking urgent medical care — DKA is a life-threatening emergency. Many people with type 1 diabetes are given a blood-ketone meter and sick-day rules for exactly this. Outside diabetes, mildly raised ketones from fasting or a ketogenic diet are usually not a concern. Mediora.AI shows blood ketones alongside glucose and bicarbonate so the diabetic-emergency pattern is visible; acting on high ketones with symptoms is urgent, guided by your diabetes team or emergency care.