What are the recommendations for a patient with diabetes (Diabetes Mellitus) experiencing an acute illness regarding their diabetic medication use, such as metformin (Biguanide) or insulin (Hormone Replacement Therapy)?

Patient Education on Diabetic Medication Use During Acute Illness

Critical First Principle: Never Stop Insulin or Oral Medications Abruptly

During acute illness, patients with diabetes must continue their insulin and oral glucose-lowering medications, with specific adjustments based on blood glucose levels and medication class. 1 This is the most important message to prevent life-threatening diabetic ketoacidosis, particularly in type 1 diabetes. 1, 2

Immediate Recognition: When to Implement Sick Day Rules

Patients should suspect volume depletion and begin sick day protocols when experiencing: 3

• Vomiting or diarrhea causing significant fluid losses 3
• Anorexia or nausea significantly decreasing fluid intake 3
• New lightheadedness, dizziness, or orthostatic symptoms 3
• Decreased weight or urine output 3

Medication-Specific Instructions

Medications to STOP Immediately During Acute Illness

Temporarily withhold these medications when volume depletion is suspected: 1, 3

• SGLT2 inhibitors (empagliflozin, dapagliflozin, canagliflozin) 1, 3
• Metformin 1, 3, 4
• ACE inhibitors/ARBs 1, 3
• Diuretics (all types: loop, thiazide, potassium-sparing) 1, 3
• NSAIDs 1, 3
• Direct renin inhibitors and ARNI 1, 3

The rationale is that these medications worsen volume depletion and increase risk of acute kidney injury during dehydrating illnesses. 3 Metformin specifically carries risk of lactic acidosis when combined with volume depletion. 4

Insulin Management: Adjust, Don't Stop

For insulin users, the approach depends on blood glucose levels: 1

• If blood glucose is LOW: Hold insulin, sulfonylureas, and meglitinides until blood glucose recovers 1
• If blood glucose is ELEVATED: Increase basal and bolus insulin by 10-20% empirically 1
• Never completely stop basal insulin, even if unable to eat 1, 2, 5

This nuanced approach prevents both hypoglycemia and diabetic ketoacidosis. 1, 2 The increased counter-regulatory hormones during illness typically increase insulin requirements. 1

Sulfonylureas and Meglitinides

Hold these medications only if blood glucose is low, and resume when blood glucose recovers. 1 Unlike insulin, these can be safely withheld during illness if hypoglycemia risk is present. 1

Essential Self-Management Actions

Glucose and Ketone Monitoring

Check blood glucose every 4-6 hours while awake throughout the duration of illness. 3 Check ketones in patients receiving SGLT2 inhibitors, insulin, or following ketogenic diets. 3 Blood β-hydroxybutyrate measurement is preferred over urine ketones. 2

Fluid Resuscitation Strategy

Increase fluid intake significantly to prevent dehydration, prioritizing sodium-containing fluids such as: 1, 3

• Broth 1
• Tomato juice 1
• Sports drinks 1

Sodium-containing fluids help prevent intravascular volume depletion more effectively than water alone. 1, 3

Carbohydrate Intake to Prevent Ketosis

Consume 150-200 grams of carbohydrate daily (approximately 45-50 grams every 3-4 hours) to prevent starvation ketosis. 1, 3 If regular food is not tolerated, use liquid or soft carbohydrate sources: 1

• Sugar-sweetened soft drinks 1
• Juices 1
• Soups 1
• Ice cream 1

Red Flags: When to Contact Healthcare Provider Immediately

Patients must contact their healthcare provider urgently for: 3

• Reduced level of consciousness or new confusion 3
• Vomiting more than 4 times in 12 hours 3
• Low blood pressure 3
• Moderate or high ketones 3
• Increased heart rate (tachycardia) 3
• Fever 3

These signs indicate potential progression to diabetic ketoacidosis or severe volume depletion requiring medical intervention. 3

Duration and Medication Resumption

Sick day protocols are appropriate for a maximum of 72 hours or until symptoms resolve. 3 Resume withheld medications within 24-48 hours of symptom resolution, but only when: 1, 3

• Eating and drinking normally 1, 3
• Adequate volume status is confirmed 3

When restarting SGLT2 inhibitors specifically, anticipate an acute drop in eGFR and reassess volume status. 3

Common Pitfalls to Avoid

The most dangerous misconception is advising patients to reduce or stop insulin during illness, which directly leads to diabetic ketoacidosis. 2 This is particularly critical in type 1 diabetes where insulin omission is the most common preventable cause of DKA. 2

Failing to check ketones in SGLT2 inhibitor users can lead to euglycemic diabetic ketoacidosis, where blood glucose may appear normal despite dangerous ketone accumulation. 3

Inadequate fluid replacement accelerates DKA development and worsens volume depletion. 2

Continuing RAAS inhibitors during volume depletion can precipitate acute kidney injury, though this is usually reversible with drug cessation. 3

Special Considerations for Type 1 vs Type 2 Diabetes

For type 1 diabetes patients, the risk of diabetic ketoacidosis is substantially higher, and insulin must never be omitted. 1, 2 Supplemental insulin is often required during illness. 1

For type 2 diabetes patients, oral medications can be more flexibly adjusted, but the same principles of monitoring and fluid intake apply. 1 Metformin must still be withheld due to lactic acidosis risk. 4

Patient Education Summary Card

Provide patients with a simple written card stating: 1, 3

1. STOP: Metformin, SGLT2 inhibitors, ACE/ARBs, diuretics, NSAIDs
2. NEVER STOP: Basal insulin (adjust dose based on glucose)
3. CHECK: Blood glucose every 4-6 hours, ketones if on insulin/SGLT2i
4. DRINK: Sodium-containing fluids frequently
5. EAT: 150-200g carbohydrate daily, even if liquid form
6. CALL: If vomiting >4 times, confused, ketones present, or fever

This algorithmic approach prioritizes prevention of both diabetic ketoacidosis and acute kidney injury while maintaining glycemic control during acute illness. 1, 3