High blood sugar symptoms: what to do and when it is an emergency

According to MedlinePlus and the CDC, the most common signs of high blood sugar are:

• Being very thirsty or having a dry mouth
• Needing to urinate often, including at night
• Blurry vision
• Tiredness or weakness
• Dry skin
• Hunger and losing weight without trying
• Sores that heal slowly or infections that keep coming back

With type 2 diabetes these symptoms usually come on slowly, and many people notice none for years: that is why most diagnoses come from a blood test. If you have any of these high blood sugar symptoms, the doctor evaluates you by video and gives you a lab order for testing. Signs of very high blood sugar (fruity breath, vomiting, fast breathing, confusion) are an emergency: see the emergency section below.

In Puerto Rico people say "el azúcar" for blood glucose. High blood sugar, or hyperglycemia, happens when the body makes too little insulin or doesn’t respond well to it, so glucose stays in the blood instead of getting into the cells.

For reference, according to the NIH, a fasting glucose of 99 mg/dL or below is normal, 100 to 125 mg/dL is prediabetes, and 126 mg/dL or above is diabetes; a glucose of 200 mg/dL or above at any time, with symptoms, also points to diabetes. For people who already have diabetes, the CDC gives a typical target of 80 to 130 mg/dL before meals and under 180 mg/dL two hours after. Your own target is set by your doctor.

Puerto Rico has the highest rate of diagnosed adult diabetes of any U.S. state or territory: 14.4% in 2021, according to the CDC.

If you have diabetes and your sugar reads high, check whether you missed a dose (of pills, insulin or a weekly injection such as Trulicity), ate more than usual, are sick or under a lot of stress: the CDC lists those causes. Drink water, follow the plan your doctor gave you and check again.

Ketones. The CDC recommends testing your urine for ketones when your blood sugar is 250 mg/dL or above. MedlinePlus advises testing if your sugar has been above your goal for no clear reason for 6 hours with type 1 diabetes, or for 3 days with type 2. If ketones are present, get medical care right away.

If you have never been told you have diabetes and you have these symptoms, don’t wait: the doctor evaluates you and gives you the lab order for testing. See also prediabetes.

In children, type 1 diabetes can appear suddenly, over a few weeks, with strong thirst, frequent urination, new bedwetting, hunger, weight loss, tiredness, nausea, vomiting or belly pain. A child with these symptoms needs to be seen the same day. If they are also vomiting, breathing fast or very drowsy, take them to the ER. If the patient is under 21, a parent or legal guardian stays on camera for the whole visit and shows ID.

Very high blood sugar can cause diabetic ketoacidosis or hyperosmolar syndrome, which are life-threatening. According to the CDC and MedlinePlus, call 911 or go to the emergency room right away if:

• Your blood sugar stays at 300 mg/dL or above
• You have high ketones in your urine
• Your breath smells fruity
• You are vomiting and can’t keep food or drinks down
• You are breathing fast and deep, or are short of breath
• You are confused or very drowsy