Why is blood glucose high after lunch and dinner?

Elevated postprandial blood glucose levels after lunch and dinner may stem from three primary causes: 1) diabetes mellitus; 2) excessive caloric intake; and 3) inappropriate medication use. Detailed analysis of these causes follows:

1. Diabetes mellitus: In individuals with diabetes, impaired insulin secretion and delayed insulin peak response often lead to marked postprandial hyperglycemia. Moreover, in patients with severe insulin resistance, elevated postprandial blood glucose may persist for an extended duration.

2. Excessive carbohydrate intake: Consuming large amounts of staple foods or sugary items at lunch or dinner readily elevates postprandial blood glucose. Patients with diabetes require strict dietary control; excessive caloric intake—whether derived from fats, proteins, or carbohydrates—can significantly impact blood glucose levels. Any food exceeding the prescribed caloric limit may contribute to postprandial hyperglycemia.

3. Inappropriate medication use: Post-lunch or post-dinner hyperglycemia may also result from improper medication use. Incorrect dosing or timing of medications can disrupt hormonal balance, thereby contributing to elevated postprandial blood glucose levels after lunch and dinner.