Monitor the illness and the glucose
Check glucose more frequently than usual as advised, record temperature and symptoms, and check ketones when your plan recommends it—particularly with type 1 diabetes, pregnancy or marked hyperglycaemia. A normal glucose reading does not make persistent vomiting harmless.
Fluids, food and medicines need a plan
Take frequent small amounts of fluid if you can keep them down. Medicine instructions differ: insulin may need adjustment rather than stopping, while dehydration can change the safety of some tablets and blood-pressure medicines. Contact your clinician or urgent service for individual instructions.
Prepare a sick-day kit
Keep a thermometer, glucose strips, ketone supplies if advised, medicine list, emergency contacts and suitable fluids or carbohydrate sources available. Make sure a family member knows the plan if you become too unwell to manage it.
Frequently asked questions
Should I stop metformin or an SGLT2 medicine when vomiting?
Dehydration may change medicine safety, but the correct action depends on the medicine and illness. Use your clinician’s written plan or obtain prompt clinical advice rather than relying on a blanket rule.
Can I exercise to reduce high sugar while ill?
Do not exercise when you are unwell, dehydrated or have ketones. It may worsen risk in some situations.
Guidelines and references
Dr. Pratyush Kumar · DNB Family Medicine, Sir Ganga Ram Hospital · DFID Diabetes Fellowship, Christian Medical College, Vellore
Updated and medically reviewed October 2026 · General education, not an individual prescription.