• Hold metformin if the patient is at risk for dehydration (eg. vomiting, diarrhea) due to the risk of lactic acidosis
• Medications that stimulate insulin secretion (eg. sulfonylureas, repaglinide, or nateglinide) should be held if the patient is at risk for hypoglycemia
• Patients usually should continue their basal insulin, but may decrease or hold their bolus dosing.
• Finger sticks should be checked every 2-4 hours for those on insulin, or 2-4 times per day for type II diabetics not on insulin.

References

Diabetes. Pharmacist's Letter March 2013;29(3):13-4.