Keeping your eating and exercise habits on a similar schedule day to day will help keep your blood glucose at healthy levels. Experts suggest these tips:

• Eat your meals and snacks at about the same times each day.
• Eat about the same amounts of food each day - don’t have a large lunch one day and a small one the next.
• Do not skip meals or snacks.
• Take your medicines at the same times each day. Your prescription will be specific, but, as a rule,
  - take regular, NPH, or Lente insulin 30 minutes before you eat
  - take Humalog insulin lispro just before you eat
  - take diabetes pills before you eat.
• Exercise at about the same times each day.

Source:  NIDDK. I have diabetes. When should I eat? Nov. 1997.