Blood Sugar 63 mg/dl — Too Low? What It Means

Shaky at 63 a few hours after lunch?

Some people get a familiar sequence: they eat a meal, feel fine, and then two to five hours later turn sweaty, weak, hungry and irritable. A meter at that moment may show something like 63 mg/dl. This pattern has a name, reactive or postprandial hypoglycemia, meaning a low that follows a meal rather than one that comes from going without food.

On this site a 63 counts as low whether you measured fasting or after eating, so the symptoms deserve to be treated the usual way first. The useful detective work starts afterwards, and timing is the main clue.

How a meal can lead to a dip hours later

After a meal rich in quickly digested starch or sugar, glucose climbs fast and the pancreas answers with a burst of insulin. In most people the two stay in step. In some, the insulin response is a little late or a little too large, so it keeps working after most of the meal’s sugar has been cleared. Glucose then drifts below where it started, and the adrenaline response that follows causes the shaky, anxious feeling.

This can happen in otherwise healthy people. It is also described in people with early insulin resistance, where the first insulin response is sluggish and the later one overshoots.

The timing separates it from a fasting low. A dip that arrives only after food, and never after a long gap without eating, points toward this pattern rather than toward the rarer causes that doctors look for when lows happen on an empty stomach.

After stomach surgery: late dumping

People who have had gastric bypass or other stomach surgery deserve a special mention. Food reaches the small intestine much faster than before, glucose spikes quickly, and a large insulin release follows. One to three hours later, glucose can fall sharply. This is called late dumping syndrome. It can appear months or even years after the operation, and the lows can be stronger than in ordinary reactive hypoglycemia. If you have had such surgery and see readings in the 60s after meals, tell your surgical team or doctor rather than managing it alone.

Testing and eating to settle the pattern

A meter reading taken while you have symptoms is far more useful than one taken after the feeling has passed. Note the time you started eating, what the meal was, when symptoms began, and the reading. Three or four logged episodes give a doctor much more to go on than a description.

Changes that people with this pattern commonly find helpful:

• smaller meals more often instead of two large ones
• pairing starch with protein, healthy fat and fiber so it digests more slowly
• fewer sugary drinks, sweet coffee drinks and juice on an empty stomach
• going easy on alcohol, which makes a later dip deeper

Ideas for slower meals are on the blood sugar diet foods page. When symptoms strike, a small amount of fast sugar brings relief, followed by something with protein so the cycle does not repeat.