Repeated drops in blood sugar usually come down to a mismatch between your body’s insulin output and its glucose supply. The clinical term is hypoglycemia, defined as blood sugar below 70 mg/dL. Mild episodes (54–69 mg/dL) cause shakiness and sweating. Moderate episodes (below 54 mg/dL) can impair your thinking and coordination. If your blood sugar keeps falling, something is consistently tipping that balance, and the cause depends on whether you have diabetes, what medications you take, and how your body handles food and stress.
Reactive Drops After Eating
One of the most common reasons blood sugar keeps dropping in people without diabetes is reactive hypoglycemia. This happens within four hours of eating, typically after a meal heavy in sugar or refined carbohydrates like white bread, pasta, or sweetened drinks. Your pancreas overshoots its insulin response, pulling blood sugar down too fast and too far. You feel shaky, anxious, sweaty, or suddenly foggy, then the symptoms ease once you eat again.
The frustrating part is that in many cases, no single underlying disease explains it. The pattern itself is the problem: eating foods that spike blood sugar quickly triggers an exaggerated insulin release. Avoiding sugary foods and processed simple carbs, especially on an empty stomach, often reduces or eliminates these episodes. Pairing carbohydrates with protein, fat, or fiber slows digestion and flattens the glucose curve enough to prevent the overcorrection.
Gastric bypass and other bariatric surgeries can also cause reactive hypoglycemia because food moves into the small intestine faster than normal, producing a rapid glucose spike followed by a steep drop. If your episodes started after weight-loss surgery, that connection is worth raising with your care team.
Diabetes Medications and Insulin
If you have diabetes, the most likely culprit is your medication. Insulin and a class of oral drugs called sulfonylureas (glipizide, glimepiride, glyburide) directly lower blood sugar, and they don’t automatically shut off when your levels are already normal. Too high a dose, a delayed or skipped meal, or an unexpected burst of physical activity can all push your glucose below 70 mg/dL.
Metformin alone rarely causes hypoglycemia, but when it’s combined with a sulfonylurea the risk increases. Several other diabetes drug classes, including SGLT2 inhibitors, can contribute to drops when paired with sulfonylureas as well. If you’re on more than one blood-sugar-lowering medication and keep having lows, the combination may need adjusting.
Exercise and Delayed Drops
Physical activity burns glucose during the workout, but the effects don’t stop when you cool down. After exercise, your muscles replenish their stored energy by pulling glucose from your bloodstream. Your body also becomes more sensitive to insulin, and that heightened sensitivity can last 24 to 48 hours. This means a blood sugar drop can hit you well into the next day, long after you’ve left the gym.
The risk is highest when you exercise strenuously, exercise for a long time, skip a meal before or after activity, or take insulin or insulin-stimulating medications. If your drops tend to follow workout days, the pattern points here. Eating a balanced snack after exercise and monitoring your levels that evening and the following morning can help you spot the connection.
How Alcohol Blocks Your Liver
Your liver acts as a glucose reservoir, releasing stored sugar into your bloodstream between meals and overnight to keep levels stable. Alcohol disrupts this process. When you drink, the chemical changes in your liver shift its priorities away from glucose production. Specifically, alcohol processing generates a byproduct that blocks the conversion of raw materials into new glucose, essentially shutting down your liver’s backup fuel system.
This matters most when you drink without eating, drink heavily, or drink in the evening and go to sleep. Your liver can’t compensate overnight, and you wake up with dangerously low blood sugar. Even moderate drinking on an empty stomach can cause a noticeable dip. If your drops tend to happen the morning after drinking, or later in the evening on days you’ve had alcohol, this mechanism is a strong candidate.
Medications You Might Not Suspect
Diabetes drugs aren’t the only medications that lower blood sugar. Several other drug classes can cause hypoglycemia, and you may not connect them to your symptoms because low blood sugar isn’t their primary purpose. Beta-blockers (commonly prescribed for high blood pressure or anxiety) can mask the warning signs of a drop while also contributing to it. Certain antibiotics, including some fluoroquinolones and the anti-malaria drug quinine, have well-documented effects on blood sugar. Even the common pain reliever indomethacin and certain heart rhythm medications have been linked to drops.
Beta-blockers deserve special attention because they can blunt the rapid heartbeat and shakiness that normally alert you to low blood sugar. You may not feel the warning signs until your levels are already quite low. If you started a new medication around the time the drops began, check whether hypoglycemia is a listed side effect.
Hormonal Causes
Cortisol, the hormone released by your adrenal glands, plays a direct role in turning food into energy and keeping blood sugar stable between meals. In adrenal insufficiency (Addison’s disease), cortisol production falls short. Low blood sugar is an early symptom, often accompanied by fatigue, darkened skin, salt cravings, and low blood pressure.
Under normal circumstances, your adrenal glands produce two to three times the usual amount of cortisol during physical stress, illness, or injury. With adrenal insufficiency, they can’t meet this demand, and blood sugar drops more severely during stressful events. A secondary form of the condition, caused by a problem with the pituitary gland rather than the adrenal glands themselves, is even more likely to cause recurring low blood sugar.
Insulinomas and Other Rare Causes
When blood sugar keeps dropping without an obvious trigger, and dietary changes don’t help, a rare insulin-producing tumor called an insulinoma becomes part of the conversation. These small, usually benign tumors sit in the pancreas and secrete insulin continuously, regardless of what your blood sugar is doing. The result is unpredictable drops that can happen at any time, including while fasting.
Doctors suspect an insulinoma when three things occur together (known as Whipple’s triad): you have symptoms of low blood sugar, a fingerstick reading confirms a level below 55 mg/dL, and your symptoms improve once you eat carbohydrates. The gold-standard diagnostic test is a supervised 72-hour fast in a hospital setting, where blood is drawn to measure insulin, related hormone fragments, and other markers once symptoms appear. Insulinomas are uncommon, but they’re treatable once identified.
Inherited metabolic disorders can also cause recurrent hypoglycemia, particularly conditions that affect how your body stores or releases glycogen (the stored form of glucose). These typically present in childhood but milder forms can go undiagnosed into adulthood.
What a Drop Feels Like
Mild hypoglycemia usually announces itself with shakiness, sweating, a pounding heart, irritability, and sudden hunger. As levels fall further, the brain starts running short on fuel: you may notice confusion, difficulty concentrating, blurred vision, slurred speech, or clumsiness. Severe episodes can cause seizures or loss of consciousness, and they require someone else’s help to treat.
These symptoms overlap with anxiety, panic attacks, and other conditions, which is why a confirmed low reading on a glucose meter matters. If you’re getting these symptoms regularly, checking your blood sugar during an episode gives you and your doctor real data to work with.
What to Do During a Drop
The standard approach is called the 15-15 rule: eat 15 grams of fast-acting carbohydrates (four glucose tablets, four ounces of juice, or a tablespoon of sugar), then wait 15 minutes and recheck your blood sugar. If it’s still below 70 mg/dL, repeat. Once your level stabilizes, follow up with a small meal or snack that includes protein to keep it steady.
Keeping glucose tablets or juice boxes accessible matters more than it might seem. Drops can impair your judgment and coordination quickly, and having a fix within arm’s reach, in your bag, your car, and your nightstand, gives you a buffer before symptoms worsen.
Patterns Worth Tracking
The single most useful thing you can do is log when your drops happen and what preceded them. Note the timing relative to meals, the composition of your last meal, any exercise that day, alcohol consumption, and medications taken. A pattern almost always emerges. Drops two to three hours after eating point toward reactive hypoglycemia. Drops the morning after drinking point toward alcohol. Drops on workout days, especially the day after intense exercise, suggest delayed post-exercise effects. Drops with no apparent trigger that happen even during fasting warrant a deeper medical workup.