A “hypo” is short for hypoglycemia, a drop in blood sugar low enough to cause noticeable symptoms and potentially harm your body. It’s most common in people with diabetes who use insulin or certain medications, but it can happen to anyone. Blood sugar below 70 mg/dL (3.9 mmol/L) is considered low, and below 54 mg/dL (3.0 mmol/L) requires immediate action.
What a Hypo Feels Like
The symptoms of a hypo come in two waves, driven by different things happening in your body. The first set of symptoms comes from your nervous system reacting to the drop in blood sugar. These are your body’s alarm signals: shaking, a pounding heartbeat, anxiety, sweating, sudden intense hunger, and tingling sensations in your lips or fingers. Most people learn to recognize these early warnings, and they’re your cue to act fast.
If blood sugar keeps falling, a second set of symptoms appears. These happen because your brain isn’t getting enough fuel. You might feel confused, unusually warm, weak, or deeply fatigued. In severe cases, this can progress to loss of coordination, slurred speech, seizures, or unconsciousness. The transition from “I feel shaky” to “I can’t think clearly” can happen quickly, which is why treating the early signs matters so much.
Common Triggers
For people with diabetes, hypos usually trace back to a mismatch between medication, food, and activity. The most common triggers include:
- Too much insulin or diabetes medication. Taking more than your body needs at that moment pushes blood sugar down too fast.
- Eating less than usual. If you skip a meal or eat a smaller portion after taking your regular dose, there isn’t enough glucose to balance the medication.
- More exercise than normal. Physical activity burns through blood sugar. A longer workout, a more intense session, or even an unusually active day can cause a drop, especially if you haven’t adjusted your food or medication.
- Alcohol. Drinking on an empty stomach is a well-known trigger, but alcohol can also cause delayed hypos hours after your last drink. Your liver, which normally releases stored glucose to keep levels stable, gets busy processing alcohol instead.
The 15-15 Rule for Treatment
The standard approach to treating a mild or moderate hypo is simple and worth memorizing. Eat or drink 15 grams of fast-acting carbohydrates, then wait 15 minutes and check your blood sugar again. If it’s still below 70 mg/dL, repeat with another 15 grams. Keep going until your levels are back in your target range.
Good sources of 15 grams of fast-acting carbs include glucose tablets, half a cup of juice or regular soda, or a tablespoon of sugar or honey. What you want is something that hits your bloodstream quickly. Foods with fat or protein (like chocolate or peanut butter crackers) slow digestion and won’t bring your levels up fast enough in an emergency.
Severe Hypos and Glucagon
A severe hypo is one where you can’t treat yourself, either because you’re too confused, you’ve lost consciousness, or you’re having a seizure. This is where glucagon comes in. Glucagon is a hormone that signals your liver to release stored sugar into the bloodstream, and it’s available as an emergency rescue treatment.
Glucagon used to come only as an injectable kit that required mixing a powder with liquid before injecting it. This proved difficult in practice. In one usability study, half of caregivers failed to administer any glucagon when using the injectable kit during a simulated emergency. A newer option is a nasal spray: a single-use device that delivers dry glucagon powder through the nose with no mixing or needles required. In the same study, 94% of caregivers successfully delivered a full dose using the nasal version. If you or someone you live with is at risk for severe hypos, having glucagon on hand and making sure the people around you know how to use it is genuinely important.
Hypo Unawareness
One of the more dangerous complications of repeated hypos is losing the ability to feel them coming. This is called hypoglycemia unawareness, and it develops gradually. Normally, your body triggers those early warning symptoms (shaking, sweating, hunger) when blood sugar drops to around 60 mg/dL. But if you experience frequent hypos, the threshold for feeling symptoms keeps shifting lower. Yesterday you might have noticed symptoms at 60 mg/dL. Today, you might not feel anything until you’re at 55 mg/dL. Next week, it could be lower still.
The problem is that the blood sugar level that causes unconsciousness doesn’t shift down with it. So the gap between “I feel fine” and “I’ve passed out” gets dangerously narrow. People with hypo unawareness often rely more heavily on continuous glucose monitors, which can alert them to dropping levels before symptoms would normally appear.
Hypos in People Without Diabetes
Hypos can also occur in people who don’t have diabetes, though this is less common. There are two main types. Reactive hypoglycemia happens after eating, typically within a few hours of a meal. It can result from your body overproducing insulin in response to food, sometimes due to enlarged insulin-producing cells in the pancreas, autoimmune conditions involving insulin antibodies, or as a consequence of stomach surgery that changes how quickly food is digested.
Fasting hypoglycemia occurs when you haven’t eaten for an extended period. Causes include certain tumors that produce excess insulin (called insulinomas), other cancers, alcohol use, and some medications. Diagnosing an insulinoma typically involves a monitored 72-hour fast to observe how blood sugar behaves without food intake. If you’re experiencing hypo symptoms regularly and you don’t have diabetes, it’s worth getting a proper evaluation, since the underlying cause determines the treatment.