Calculating Correction Doses for Diabetic Patients Using Basalog and Fiasp During Ramadan
Use the insulin sensitivity factor (ISF) formula to calculate correction doses: divide 1800 by your total daily insulin dose to determine how many mg/dL one unit of Fiasp will lower blood glucose, then divide the difference between current glucose and target glucose by this ISF number. 1
Understanding the Correction Dose Formula
The correction dose calculation follows this algorithmic approach:
Step 1: Calculate your Insulin Sensitivity Factor (ISF)
- ISF = 1800 ÷ Total Daily Dose (TDD) of insulin 1
- For example, if your TDD is 60 units, your ISF = 1800 ÷ 60 = 30 mg/dL per unit
- This means one unit of Fiasp will lower your blood glucose by approximately 30 mg/dL 1
Step 2: Determine the glucose correction needed
- Correction needed = (Current glucose - Target glucose) 1
- For example, if current glucose is 220 mg/dL and target is 120 mg/dL, you need to correct 100 mg/dL
Step 3: Calculate correction dose
- Correction dose = Correction needed ÷ ISF 1
- Using the example above: 100 ÷ 30 = 3.3 units (round to 3 units with most pens) 1
Critical Ramadan-Specific Modifications
During Ramadan fasting, reduce your total insulin doses significantly to prevent dangerous hypoglycemia:
- Give 60% of your pre-Ramadan TDD as Basalog (insulin glargine) in the evening 2
- Give 40% of your pre-Ramadan TDD as Fiasp (ultra-rapid-acting insulin), split between Suhoor (predawn meal) and Iftar (sunset meal) 2
- Your ISF calculation must use this reduced TDD, not your pre-Ramadan dose 2
For example: If your pre-Ramadan TDD was 60 units:
- Ramadan TDD = 60 × 0.70 = 42 units total 2
- Basalog evening dose = 42 × 0.60 = 25 units 2
- Fiasp total = 42 × 0.40 = 17 units (split between meals) 2
- New ISF for corrections = 1800 ÷ 42 = 43 mg/dL per unit 1, 2
Timing of Correction Doses During Ramadan
Administer Fiasp correction doses at these specific times:
- At Iftar (sunset meal) when breaking the fast, combined with your mealtime dose 3, 2
- At Suhoor (predawn meal) if glucose is elevated, combined with your mealtime dose 3, 2
- Never give correction doses during fasting hours unless glucose exceeds 300 mg/dL, which requires breaking the fast immediately 2
Mandatory Safety Thresholds
You must break the fast immediately under these conditions:
- Blood glucose drops below 70 mg/dL 3
- Blood glucose rises above 300 mg/dL to prevent diabetic ketoacidosis 2
- Consider breaking the fast if glucose drops below 80 mg/dL 2
Intensive Monitoring Requirements
Check blood glucose at these critical time points during the first 3-4 weeks of Ramadan:
- First few hours after starting the fast 3, 4
- Late afternoon before breaking fast (highest hypoglycemia risk) 3, 4
- Post-Iftar (2 hours after eating) to detect hyperglycemia 3
- Pre-Suhoor 5
- Every 4 hours if using insulin pump therapy 5
Common Pitfalls to Avoid
Do not make these dangerous errors:
- Never use your pre-Ramadan ISF for correction calculations during Ramadan—this will cause severe hypoglycemia because your TDD has been reduced 2
- Never give aggressive correction doses during fasting hours; wait until Iftar unless glucose exceeds 300 mg/dL 2
- Never skip the 30% dose reduction during Ramadan—using 100% of pre-Ramadan doses dramatically increases hypoglycemia risk 2
- Avoid correcting glucose levels below 150 mg/dL during fasting hours, as this increases hypoglycemia risk 2
Adjusting the ISF if Corrections Are Ineffective
If your correction doses consistently fail to bring glucose into target range:
- Recalculate your TDD by adding all insulin doses (Basalog + all Fiasp doses) over 24 hours 1
- If corrections consistently overshoot (causing hypoglycemia), your ISF is too low—increase the ISF number 1
- If corrections consistently undershoot (glucose remains high), your ISF is too high—decrease the ISF number 1
- Make adjustments in 10-20% increments and reassess after 2-3 days 1