Sick-Day Glucose Impact Calculator

Illness triggers the body's stress response - releasing cortisol and adrenaline - which raises blood glucose even if you're not eating. Estimated BG impact by illness type:

Fever adds an additional ~10 mg/dL per degree Celsius above 37 degC. Vomiting or inability to eat lowers glucose but increases DKA risk - especially in Type 1 diabetes or SGLT-2 users.

Surgery recovery often triggers significant insulin resistance, requiring 20-50% more insulin than usual - always follow your surgical team's protocol.

• Never stop insulin - even if you can't eat, your body still needs background insulin to prevent DKA.
• Check your blood glucose every 2-4 hours while ill - more frequently if BG exceeds 14 mmol/L (252 mg/dL).
• Check ketones if BG is above 14 mmol/L (252 mg/dL) or you're vomiting - especially for T1 diabetes.
• Stay hydrated - aim for 250 ml (1 cup) of sugar-free fluid every hour to prevent dehydration.
• If using an SGLT-2 inhibitor, apply the sick-day pause rule and check with your prescriber.
• Metformin may need to be paused during severe illness (vomiting, dehydration) - check with your team.
• Keep glucose tablets or juice nearby in case hypoglycaemia occurs from reduced eating.
• Call your diabetes team if: BG is above 20 mmol/L (360 mg/dL), ketones are moderate/large, you cannot keep fluids down for more than 4 hours, or you feel confused.