Repeated blood sugar drops happen when your body produces too much insulin after meals, when medications push glucose too low, or when your liver can’t release stored sugar fast enough to keep up with demand. A blood sugar reading below 70 mg/dL is considered low, and below 54 mg/dL is clinically significant. If your sugar keeps dropping, something is disrupting the balance between how much glucose enters your blood and how quickly it gets used up or cleared away.
The Post-Meal Crash
The most common reason for recurring sugar drops in people without diabetes is reactive hypoglycemia, where blood sugar falls too low within a few hours of eating. Here’s what happens: you eat a meal (especially one high in refined carbohydrates), your blood sugar spikes, and your pancreas releases a burst of insulin to bring it down. But the insulin response overshoots, pulling your blood sugar lower than where it started. This typically hits one to three hours after eating.
Processed foods, white bread, sugary drinks, and anything that digests quickly tends to trigger larger insulin surges. The more processed a food is, the faster it raises blood sugar and the steeper the crash that follows. Foods with more fiber and fat slow that process down, producing a gentler rise and a gentler landing. The total amount of carbohydrate in a meal also matters. A giant plate of pasta will provoke a bigger insulin response than a smaller portion, regardless of what else is on the plate.
There’s also a condition called idiopathic postprandial syndrome, where people feel all the symptoms of low blood sugar (shakiness, brain fog, sweating) after eating, but their glucose readings are actually normal. It mimics a sugar crash without one truly occurring. The distinction matters because the fix for each is different. Confirming that your symptoms line up with an actually low reading, and that they resolve when you eat something, is the key diagnostic step.
Medications That Lower Blood Sugar
Several classes of medication can cause blood sugar to drop, even if they weren’t prescribed for diabetes. Sulfonylureas, a common type of diabetes drug, directly stimulate your pancreas to release more insulin. If the dose is slightly too high or you skip a meal, that extra insulin has nowhere to go and your sugar falls.
Other medications linked to low blood sugar include beta-blockers (used for blood pressure and heart conditions), certain antibiotics in the fluoroquinolone family, and the antimalarial drug quinine. Beta-blockers are particularly tricky because they can also mask the warning signs of a drop. Normally your heart races and you feel jittery when sugar falls. Beta-blockers blunt those signals, so the first symptom you notice might be confusion or dizziness rather than the early warnings.
If your drops started around the same time as a new prescription or a dosage change, that connection is worth investigating.
How Alcohol Blocks Your Safety Net
Your liver acts as a glucose reserve. When blood sugar starts to dip between meals or overnight, your liver converts stored glycogen into glucose and releases it into your bloodstream. Alcohol disrupts this process at a chemical level. When your liver is busy metabolizing ethanol, it can’t efficiently produce new glucose. Alcohol shifts the liver’s internal chemistry in a way that blocks the conversion steps needed to turn stored energy into usable blood sugar.
This is why blood sugar can drop dangerously hours after drinking, especially if you haven’t eaten much. The risk is highest on an empty stomach and persists for as long as alcohol is being processed, which can take many hours depending on how much you drank. Even moderate drinking can cause a noticeable dip if it coincides with a skipped meal or an extended gap between eating.
Exercise-Related Drops
Physical activity pulls glucose out of your blood and into your muscles. During a workout, that effect is immediate. But the drop can also hit several hours later, because your muscles remain more sensitive to insulin after exercise and continue absorbing glucose to replenish their energy stores. Prolonged or intense exercise can also deplete the glycogen reserves in your liver, reducing its ability to stabilize blood sugar afterward.
This delayed effect catches people off guard. You might feel fine during and right after a run, then experience shakiness or brain fog later that evening. The more intense or prolonged the session, the longer this window of vulnerability lasts.
Overnight Drops and Morning Highs
If your sugar drops while you’re asleep, your body fights back. The drop triggers a release of stress hormones, growth hormone, and glucagon, all of which tell your liver to dump glucose into your bloodstream. The result is a rebound: low sugar at 2 or 3 a.m. followed by unusually high sugar when you wake up. This is called the Somogyi effect.
The confusing part is that you might only see the high morning reading and assume you need more medication or less food at night, when the real problem is the opposite. A continuous glucose monitor or a middle-of-the-night finger stick can reveal whether a hidden overnight low is driving those morning highs.
Hormonal and Organ-Related Causes
Your body relies on several hormones to keep blood sugar from falling too low, and cortisol is one of the most important. Cortisol signals your liver to release glucose and helps maintain blood sugar between meals. When your adrenal glands don’t produce enough cortisol, a condition called adrenal insufficiency, blood sugar regulation breaks down. This can stem from problems with the adrenal glands themselves (Addison’s disease) or, more commonly, from the pituitary gland failing to send the right signals to the adrenals.
Pituitary-related adrenal insufficiency is more common than the primary form and tends to be diagnosed in people in their 60s. It causes low blood sugar more frequently than Addison’s disease does, particularly when combined with illness, fasting, or physical stress. Other clues that point to this cause include low blood pressure, persistent fatigue, and abnormal sodium levels in blood work.
Liver disease and kidney disease can also cause recurring drops. Your liver stores and releases glucose, so when it’s damaged, that buffer shrinks. Your kidneys help clear insulin from the bloodstream, so impaired kidney function can cause insulin to linger longer than it should, pulling sugar down further.
How to Stabilize Recurring Drops
The immediate fix for a sugar drop follows the 15-15 rule: eat 15 grams of fast-acting carbohydrate (about 4 glucose tablets, half a cup of juice, or a tablespoon of honey), then wait 15 minutes. If you still feel off after 15 minutes, repeat. This gets glucose into your blood quickly without overshooting into a spike.
For prevention, the pattern of your drops tells you where to focus. If they happen after meals, shifting toward meals with more protein, healthy fat, and fiber while reducing refined carbs can blunt the insulin overshoot. Smaller, more frequent meals spread the glucose load across the day instead of creating large spikes and crashes. If your drops happen after exercise, having a snack that combines carbs and protein within the post-workout window helps replenish glycogen without triggering a new spike.
If your drops are frequent, unpredictable, or severe enough to cause confusion or near-fainting, that points toward a cause that dietary changes alone won’t fix. Persistent low blood sugar that can’t be explained by meals, medication, exercise, or alcohol warrants blood work to check cortisol levels, liver function, kidney function, and insulin levels. The pattern and timing of your episodes give a clinician the clearest roadmap to the underlying cause.