How Low Blood Sugar Happens

Glucose is a type of sugar. It is the main fuel your body uses to work. Your brain runs almost entirely on glucose, so it needs a steady supply. Glucose mostly comes from the food you eat.

When blood sugar falls too low, your brain runs short of fuel.

Insulin and some diabetes pills can lower blood sugar. Sulfonylureas, one kind of pill, make your body release more insulin. A low can happen when they act more strongly than your food.

Picture a scale. Food adds weight to one side. Medicine adds weight to the other.

When the medicine side is heavier, blood sugar can fall. Ask your care team which of your medicines can cause lows.

A seesaw holds medicine, an insulin pen and a pill, on one end and a plate of food on the other, next to a blood sugar meter. When the two sides balance, the meter reads 110 mg/dL. Skipping a meal empties the food side. Heavy exercise or a glass of alcohol joins the medicine side. Each time, the medicine side sinks and the meter drops to 60 mg/dL, a low. With alcohol, the amount matters.

Skipping a meal can lower blood sugar. So can eating less than usual, or doing heavy exercise. Each one can pull blood sugar down.

A low can happen at any time of day. It can come on even when you feel fine.

Key takeaways

• Your brain runs almost entirely on glucose from your blood.
• Medicine, skipped meals, eating less or heavy exercise can pull blood sugar down.
• A low can happen at any time, even when you feel fine.

Try it

Today, jot down your meal times, and note any meal you skipped or ate less of.