Various factors can impact blood sugar levels, including consuming carbohydrates, missing medication or insulin doses, lack of exercise, corticosteroid medications, illness, surgery, stress, dawn phenomenon, smoking, dehydration, and puberty. Conversely, missing meals, taking excess medication or insulin, and physical activity can lower blood sugar levels. Additionally, factors like menstruation, timing of food and medication/insulin, alcohol consumption, and non-diabetes medication interactions can raise or lower blood sugar depending on individual biology.