If your ketones are high, the most important steps are to hydrate aggressively, avoid exercise, and check your levels every few hours. Blood ketone readings above 1.6 mmol/L put you at high risk for diabetic ketoacidosis (DKA), a life-threatening complication that requires emergency care. What you do next depends on your exact reading, whether you have diabetes, and how you’re feeling.
Know Your Ketone Level
Not all elevated ketones are equally dangerous. Blood ketone meters give you a number in millimoles per liter (mmol/L), and each range calls for a different response:
- Below 0.6 mmol/L: Normal. No action needed.
- 0.6 to 1.5 mmol/L: Low to moderate risk. Contact your healthcare provider for guidance.
- 1.6 to 2.9 mmol/L: High risk of DKA. Go to the emergency room.
- 3.0 mmol/L or above: Very high risk. Go to the emergency room immediately.
If you’re using urine test strips instead of a blood meter, keep in mind that they’re significantly less reliable. Urine strips miss ketosis entirely about half the time at lower levels, detecting only 52% of cases when blood ketones are at or above 0.5 mmol/L. They measure a different ketone than the one most clinically relevant, and reading the color change is subjective. If you’re concerned about accuracy, a blood ketone meter (around $25 for the device, about $0.70 per test strip) gives a much more trustworthy number.
Immediate Steps to Lower Ketones
For readings in the low-to-moderate range (0.6 to 1.5 mmol/L), you can start managing at home while you contact your provider. Here’s what to do right away:
Drink water steadily. Aim for a full 8-ounce glass every 30 to 60 minutes. Your kidneys clear ketones through urine, so staying well hydrated helps your body flush them out faster. Dehydration makes ketone buildup worse and accelerates the slide toward DKA.
Do not exercise. This is counterintuitive for many people, but physical activity when ketones are elevated can drive them higher. Your body is already burning fat at an unsustainable rate, and exercise accelerates that process. Skip workouts entirely until your ketones return to normal.
Keep eating carbohydrates. If you can keep food down, eating carbs helps your body shift back to using glucose for energy, which slows ketone production. If you can’t tolerate meals, aim for about 50 grams of carbohydrates every four hours. That’s roughly a cup and a half of fruit juice or unsweetened applesauce.
Recheck every three hours. Test both your blood sugar and your ketones at least every three hours to make sure levels are trending downward, not climbing.
If You Have Diabetes
High ketones in people with diabetes almost always signal an insulin problem. When your body doesn’t have enough insulin, it can’t move glucose into cells for energy. Instead, it breaks down fat at a massive rate, flooding the bloodstream with ketone byproducts. About 80% of energy production shifts to fat burning during insulin deficit, and ketone levels can spike to dangerous concentrations far faster than your kidneys can clear them.
The critical distinction is between nutritional ketosis (the mild, controlled state people on low-carb diets enter) and ketoacidosis. In nutritional ketosis, ketones typically stay below 3 mmol/L and your blood pH remains normal. In DKA, ketones can surge to 20 to 25 mmol/L, overwhelming your body’s ability to buffer the acid. This is the scenario that becomes a medical emergency.
Don’t stop taking your insulin. Continue your usual long-acting insulin dose. If your diabetes care team has given you a sick-day plan that includes extra rapid-acting insulin for ketone correction, follow that protocol. If you don’t have a plan in place, call your provider for dosing guidance rather than guessing.
Warning Signs of Ketoacidosis
DKA can develop within 24 hours, sometimes faster. The symptoms to watch for include extreme thirst, frequent urination, nausea or vomiting, abdominal pain, weakness, shortness of breath, confusion, and a distinct fruity smell on the breath. These symptoms often cluster together, and their combination is what signals a crisis rather than any single symptom alone.
If you’re vomiting and can’t keep liquids down for more than four hours, or can’t keep food down for more than 24 hours, that’s an emergency regardless of your ketone reading. Vomiting creates a dangerous cycle: you can’t hydrate, you can’t eat carbs, and you may not be able to keep oral medication down. At that point, you need IV fluids and medical monitoring.
Managing Ketones When You’re Sick
Illness is one of the most common triggers for rising ketones in people with diabetes. Stress hormones released during infection or fever work against insulin, pushing blood sugar up and making ketone production more likely. The CDC recommends testing blood sugar every four hours when you’re sick, even if readings have been in your target range. Continue all your medications, eat as normally as possible, and drink plenty of water.
Some practical thresholds: if you have ketones in your urine at all while sick, call your doctor. If you have both vomiting or severe diarrhea lasting more than six hours and detectable ketones, head to the emergency room. The combination of illness, dehydration, and rising ketones can escalate quickly.
High Ketones Without Diabetes
Not everyone with high ketones has diabetes. Prolonged fasting, very low-carb diets, heavy alcohol use, and extended intense exercise can all produce elevated ketone levels. In most of these cases, the body is doing exactly what it’s designed to do: burning fat for fuel when glucose is scarce.
Alcoholic ketoacidosis is a separate and serious condition. Heavy drinking disrupts the same hormonal balance that goes wrong in diabetic ketoacidosis, with decreasing insulin production and rising glucagon levels. On top of that, the liver converts ethanol’s breakdown products directly into ketone bodies, creating a double source of accumulation. If someone who drinks heavily develops nausea, vomiting, and abdominal pain, ketoacidosis should be considered.
For people on ketogenic diets, mild ketone elevation (typically 0.5 to 3.0 mmol/L) is the intended goal and isn’t dangerous when blood sugar and pH remain normal. The concern arises only if levels climb unusually high, if you feel unwell, or if you have an underlying condition that affects insulin production.
Choosing the Right Ketone Test
Blood ketone meters measure the specific ketone body that matters most clinically, giving you a precise number in mmol/L. Urine strips are cheaper (about $0.10 per strip versus $0.70 for a blood test strip) and don’t require a finger prick, but their accuracy drops sharply at lower concentrations. At mild ketosis levels, urine strips produce false negatives 65% of the time. They’re better at detecting higher levels, catching 76% of cases when blood ketones reach 1.0 mmol/L or above, but that still means nearly one in four high readings gets missed.
If you’re managing diabetes and monitoring for DKA risk, a blood meter is worth the investment. If you’re tracking ketosis for a diet, urine strips can give you a general sense of whether you’re in ketosis but shouldn’t be trusted for precise readings.