Why is blood sugar high before meals and low after meals?

In daily life, when people measure their blood sugar before and after meals, they often find that the blood sugar before meals is higher than that after meals. So, why is the blood sugar high before meals and low after meals?

Excessive insulin secretion and delayed peak

Under normal circumstances, blood sugar levels rise after a meal, reaching a peak in about 30 to 60 minutes before falling. Plasma insulin levels also rise to a peak in 30 to 60 minutes, 5 to 10 times the baseline value, then fall and return to the baseline level in 3 to 4 hours. Therefore, although blood sugar levels rise after a meal in a normal person, they fluctuate within a certain range. Type 2 diabetes patients may have excessive insulin secretion (hyperinsulinemia) and delayed peak levels. Insulin remains at a relatively high concentration and cannot return to the baseline level, resulting in low blood sugar levels after a meal, or even hypoglycemia.

Insufficient eating and excessive post-meal exercise

Diet and exercise are two important basic measures for diabetes treatment. Strict diet control and proper exercise are conducive to weight loss, improving hyperglycemia and reducing hypoglycemic drugs. However, the diet plan should be strictly and long-term, and exercise should be regular. If the diet is insufficient or the intensity of post-meal exercise is too high, the patient may also have low blood sugar after meals, or even hypoglycemia.

Drugs

Excessive dosage of hypoglycemic drugs, mismatch with diet, or simultaneous use of other drugs that enhance the blood sugar-lowering effect of hypoglycemic drugs may also lead to a significant decrease in postprandial blood sugar.