📉 Hypoglycemia (Low Blood Sugar): Symptoms, Causes & How to Treat It

For many people with diabetes, a blood sugar drop can feel sudden and terrifying — shakiness, sweating, confusion, and a racing heart. Hypoglycemia (low blood sugar), generally defined as a glucose level below 70 mg/dL, is the most common acute complication of diabetes treatment. It can happen to anyone on insulin or certain oral medications, but it is manageable — and preventable — with the right knowledge. Dr. Ravi Sishir Reddy explains what causes hypoglycemia, how to recognise it early, and exactly what to do when it strikes.

1. What Is Hypoglycemia?

Hypoglycemia is a condition in which the blood glucose level falls below the normal fasting range. The usual threshold for clinical significance is below 70 mg/dL (3.9 mmol/L). However, symptoms can occur at slightly higher levels if the drop is rapid. Severe hypoglycemia is defined as a low glucose event requiring the assistance of another person to administer carbohydrates or glucagon, often accompanied by loss of consciousness or seizures.

2. Common Causes of Hypoglycemia in Diabetes

• Too much insulin or sulfonylurea: An excessive dose, or mistiming of a dose relative to food intake.
• Skipping or delaying a meal: Especially after taking rapid‑acting insulin.
• Unplanned or prolonged exercise: Muscles consume more glucose, and the effect can last for hours after activity ends.
• Alcohol consumption: Especially on an empty stomach — alcohol blocks the liver from releasing glucose for several hours.
• Weight loss without medication adjustment: Improved insulin sensitivity means the same dose may now be too high.
• Kidney disease: Reduced clearance of insulin or sulfonylureas prolongs their effect.

3. Recognising the Symptoms of Hypoglycemia

Symptoms can be divided into adrenergic (autonomic) — the body's early warning — and neuroglycopenic — brain dysfunction due to glucose deprivation.

• Mild to moderate (adrenergic): Shakiness, sweating, palpitations, hunger, anxiety, tingling around the mouth.
• Moderate to severe (neuroglycopenic): Confusion, difficulty concentrating, blurred vision, slurred speech, drowsiness, behavioural changes (irritability, aggression), and eventually seizures and unconsciousness.

Some people with long‑standing diabetes develop hypoglycemia unawareness — they no longer feel the early warning symptoms and can progress directly to confusion or loss of consciousness. This is particularly dangerous and requires careful monitoring and therapy adjustment.

4. The Rule of 15: How to Treat Low Blood Sugar

If you feel low and your glucose is confirmed to be below 70 mg/dL (or if you feel symptoms and cannot test), follow the Rule of 15:

1. Take 15 grams of fast‑acting carbohydrate. Good options include:
   • 3‑4 glucose tablets (available at any pharmacy)
   • ½ cup (120 ml) of fruit juice (apple, orange) or a regular (non‑diet) soft drink
   • 1 tablespoon of sugar, honey, or jaggery dissolved in water
   • 5‑6 hard candies (like peppermint) that you can chew quickly
2. Wait 15 minutes and recheck your blood sugar.
3. If it is still below 70 mg/dL, repeat: Take another 15 grams of fast‑acting carbs and recheck in 15 minutes.
4. Once your glucose is above 70 mg/dL, eat a small snack containing protein and complex carbohydrates to stabilise your blood sugar, especially if your next meal is more than an hour away. Examples: a slice of whole‑wheat bread with peanut butter, a small bowl of dahi with a handful of nuts, or a glass of milk with a biscuit.

Do not overtreat hypoglycemia by eating too much. It can cause a rebound high blood sugar. Also, avoid high‑fat foods (chocolate, chips) as the fat slows carbohydrate absorption.

5. Severe Hypoglycemia: When You Cannot Eat or Drink

If a person is unconscious, having a seizure, or unable to swallow safely, do not attempt to pour juice or sugar into their mouth — they may choke. This is a medical emergency:

• Glucagon injection: Glucagon is a hormone that tells the liver to release stored glucose. It is available as an emergency injection kit or a ready‑to‑use nasal powder (Baqsimi). Every person on insulin should have glucagon at home, and family members should be trained to use it.
• Call an ambulance immediately if glucagon is not available or if there is no response within 10‑15 minutes after administration.
• Once the person is awake and able to swallow, give them a snack and continue to monitor glucose closely, as glucagon wears off and hypoglycemia can recur.

6. Preventing Nighttime Hypoglycemia

Nighttime lows are especially dangerous because they can go unrecognised during sleep. To reduce the risk:

• Check your blood sugar before bed. If it is below 100‑120 mg/dL, consider a small protein‑and‑carb snack (e.g., a glass of milk, a small banana with a few almonds).
• If you exercised during the day, be extra cautious — the hypoglycemic effect of exercise can be delayed by 6‑12 hours.
• Use a CGM (continuous glucose monitor) with low‑glucose alarms if you have frequent nighttime lows or hypoglycemia unawareness.
• Discuss your insulin regimen with your doctor. Switching to a peakless long‑acting insulin (like degludec) may reduce nighttime hypoglycemia compared to older basal insulins like NPH.
• Avoid alcohol in the evening, especially without food.

7. What Is Hypoglycemia Unawareness?

After many years of diabetes, or with frequent hypoglycemic episodes, the body's autonomic warning system can become blunted. You may no longer feel shakiness or sweating until the glucose is dangerously low. This increases the risk of severe events. Strategies to regain awareness include strict avoidance of hypoglycemia for several weeks, using a CGM with alarms, and adjusting targets to allow slightly higher glucose levels temporarily. If you suspect you have lost hypo awareness, tell your doctor — it is a reversible condition in many cases.