What Blood Sugar Level Is Dangerous? Highs and Lows

Blood sugar that drifts a little above or below the ideal range is common and usually manageable. Some readings, though, need quick action, and a few are true emergencies. Knowing where the danger zones begin helps you stay calm and do the right thing at the right time. This guide is for general awareness and does not replace your own doctor's advice.

What level of sugar is dangerous?

There is no single magic number, because it depends on the direction and on how you feel. As a broad guide, a sugar below 70 mg/dL is too low, and one that climbs above 250 mg/dL is worryingly high. The table below shows the levels where you should act, and the levels where you should not wait at all.

These are general adult figures. People who have lived with diabetes for years may feel symptoms at different points, and your doctor may set personal targets for you. Use the numbers as a guide, not as a reason to ignore how your body feels.

Why do the low numbers get so much attention? Because the brain runs on glucose. When sugar falls too far, thinking, balance and even breathing can be affected within a short time. A very high sugar is serious too, but it usually causes harm over hours rather than minutes. That is why a low reading needs treating on the spot, while a high one needs a clear plan and, at times, urgent care.

Low blood sugar (hypoglycaemia): signs to know

Low sugar can come on within minutes, often after a missed meal, extra activity, too much insulin or some diabetes tablets. It is important to catch it early, because it can drop further. Common warning signs include:

• Sudden shakiness, sweating or a pounding heart
• Hunger, dizziness or feeling faint
• Irritability, confusion or trouble concentrating
• Pale skin, tingling lips or blurred vision
• In a severe drop: slurred speech, fits or loss of consciousness

The 15-15 rule for low sugar

If you can swallow safely and the reading is low but you are awake, the 15-15 rule is a handy first step. Take about 15 grams of fast-acting sugar, for example three or four glucose tablets, a small glass of fruit juice or a spoon of ordinary sugar in water. Wait 15 minutes and check again. If it is still below 70 mg/dL, repeat the same step. Once you feel better, eat a small snack or your next meal so the sugar does not fall again. If the person cannot swallow, is very drowsy or unconscious, do not force food or water. Call 108 straight away.

High blood sugar: when to worry

A single high reading after a heavy meal or a stressful day is not usually an emergency. High sugar often builds quietly, so you may not feel unwell even when the number is high. Sugars that stay high over days, or a very high value with certain symptoms, are a different matter. Speak to a doctor today if your readings keep sitting above 250 mg/dL. Treat it as an emergency and call 108 if a high sugar comes with any of these:

• Vomiting or stomach pain that will not settle
• Deep, fast breathing or a fruity smell on the breath
• Drowsiness, confusion or difficulty staying awake
• Dry mouth, sunken eyes and passing very little urine

These can be signs of diabetic ketoacidosis (DKA), a serious complication that needs hospital care without delay. It is more common in type 1 diabetes but can happen in type 2 as well, often during an infection or when insulin is missed. Never stop your prescribed insulin on your own, even when you are not eating well, unless your doctor tells you to.

Danger zones are easier to handle when you have a plan. If you or a family member often see very low or very high readings, our diabetes doctors at Prudent International Health Clinic in Viman Nagar, Pune can review your medicines and help you feel steadier. We are open all 7 days, with walk-ins welcome.