Fiasp at Lunch and Dinner: Yes, Continue Mealtime Coverage
Even with excellent breakfast postprandial and fasting glucose control, you should continue administering Fiasp (insulin aspart) at lunch and dinner, as each meal requires its own prandial insulin coverage to control postprandial glucose excursions. 1
Why Each Meal Needs Its Own Insulin Coverage
Rapid-acting insulin analogs like Fiasp have a duration of action of only 3-5 hours and are designed to blunt the postprandial glucose excursion after each specific meal, not to provide coverage for subsequent meals. 1 The breakfast Fiasp dose controls the post-breakfast glucose rise but does not extend to lunch or dinner. 1
Understanding Insulin Action Profiles
- Basal insulin (Basalog/insulin glargine) provides continuous background insulin coverage throughout the day, suppressing hepatic glucose production between meals 1
- Prandial insulin (Fiasp) addresses the acute glucose rise from carbohydrate absorption during and after each meal 1
- Pre-lunch glucose is controlled predominantly by basal insulin, not by the breakfast prandial insulin 1
- Pre-dinner glucose depends on BOTH basal insulin AND the prandial insulin given at lunch 1
The Basal-Bolus Principle
In a properly designed basal-bolus regimen, approximately 50% of total daily insulin should be given as basal insulin and 50% as prandial insulin divided among meals. 1 This distribution ensures:
- Adequate between-meal glucose control (basal component) 1
- Prevention of postprandial hyperglycemia after each meal (prandial component) 1
What Happens Without Lunch and Dinner Coverage
If you discontinue Fiasp at lunch and dinner while maintaining only breakfast coverage:
- Post-lunch and post-dinner glucose excursions will occur, even if fasting and post-breakfast values are controlled 2
- The basal insulin alone cannot adequately suppress the glucose rise from carbohydrate intake at these meals 1
- Over time, HbA1c will rise despite acceptable fasting glucose values 2
Clinical Evidence Supporting Mealtime Coverage
Randomized trials demonstrate that basal-bolus therapy provides superior glycemic control compared to basal-only regimens when postprandial hyperglycemia is present. 1 The "basal plus" strategy—adding prandial insulin one meal at a time—is specifically designed for patients who need intensification beyond basal insulin alone. 3
Fiasp-Specific Data
Recent evidence shows that Fiasp provides noninferior postprandial glucose control compared to standard insulin aspart (Novolog) in hospitalized patients with type 2 diabetes, with 4-hour postprandial time in range of 45% versus 36%. 4 This demonstrates the importance of mealtime insulin for controlling postprandial excursions.
Monitoring Strategy
To confirm the need for continued mealtime coverage:
- Check 2-hour postprandial glucose after lunch and dinner to assess adequacy of prandial insulin 1, 5
- Target postprandial glucose <180 mg/dL 1, 5
- If postprandial values consistently exceed 180 mg/dL without lunch/dinner Fiasp, this confirms the need for continued coverage 2
Dose Adjustment Approach
Each meal's Fiasp dose should be titrated independently based on 2-hour postprandial glucose readings for that specific meal. 1, 5
- Increase by 1-2 units or 10-15% every 3 days if postprandial glucose remains elevated 1, 5
- Decrease by 10-20% if hypoglycemia occurs 1, 5
- Administer Fiasp 0-15 minutes before each meal 1, 5
Common Pitfall to Avoid
Do not assume that good fasting glucose control means basal insulin alone is sufficient. 2 Fasting glucose reflects basal insulin adequacy, while postprandial glucose reflects prandial insulin adequacy—these are separate components that must both be addressed. 1 Discontinuing mealtime insulin based solely on fasting values will lead to uncontrolled postprandial hyperglycemia and suboptimal HbA1c. 2