Calculation of Initial Insulin Pump Requirements in Pregnancy
Two pregnancy-oriented approaches: AACE pregnancy protocol and Sweet Success three-rate schedule. Both include TDD plus quick estimates for ISF (1800 rule) and ICR (300/400 rules). BETA TESTING
Day before pump start:
- Discontinue use of long-acting insulin (NPH, Lantus).
- Continue injecting rapid acting or regular insulin before meals.
- Eat breakfast and inject rapid insulin or regular as usual.
AACE pregnancy protocol (Type 1 DM) — basal + meal bolus by gestation × kg
What this section calculates
- Basal total = (units × kg) × weight
- Meal bolus total = (units × kg) × weight; suggested per-meal = total ÷ 3
- AACE TDD (worksheet) = basal total + meal bolus total
- ISF ≈ 1800/TDD; ICR breakfast ≈ 300/TDD; ICR lunch/dinner ≈ 400/TDD
Basal total requirement
—U/day
Meal bolus total
—U/day
Suggested bolus before each meal (÷ 3)
—U
AACE TDD (basal + bolus total)
—U/day
ISF (1800 rule)
—mg/dL per 1U
ICR breakfast (300/TDD)
—g per 1U
ICR lunch/dinner (400/TDD)
—g per 1U
Basal delivered by schedule (check)
—U/day
AACE time-of-day basal schedule
Rates shown as U/hr
Enter inputs and click Calculate.
References (AACE / pump basics / ratios)
- Grunberger G, et al. Statement by the American Association of Clinical Endocrinologists Consensus Panel on insulin pump management. Endocr Pract. 2010;16(5):746–762. PMID: 21356638
- Kuroda A, Yasuda T, Takahara M, et al. Carbohydrate-to-insulin ratio is estimated from 300–400 divided by total daily insulin dose in type 1 diabetes patients who use the insulin pump. Diabetes Technol Ther. 2012;14(11):1077–1080. doi:10.1089/dia.2012.0109. PMID: 23101953
- Walsh J. Pumping Everything for Success on an Insulin Pump. San Diego, CA: Torrey Pines Press; 2016.
Sweet Success basal schedule (three basal rates)
- #1 basal rate (j) = h × 0.8. Used 12 AM → 4 AM.
- #2 basal rate (i) = h × 1.2. Used 4 AM → 9 AM.
- #3 basal rate (h) = total daily pump basal ÷ 24 (U/hr). Used 9 AM → 12 AM.
Basal total used
—U/day
12 AM → 4 AM (j)
—U/hr
4 AM → 9 AM (i)
—U/hr
9 AM → 12 AM (h)
—U/hr
Basal delivered by schedule (check)
—U/day
Difference vs basal total
—U/day
TDD used for ISF/ICR
—U/day
ISF (1800 rule)
—mg/dL per 1U
ICR breakfast (300/TDD)
—g per 1U
ICR lunch/dinner (400/TDD)
—g per 1U
Sweet Success time-of-day basal schedule
Rates shown as U/hr
Choose an input mode and calculate.
References (Sweet Success / ratios)
- California Diabetes and Pregnancy Program (CDAPP) Sweet Success. Guidelines for Care. Revised edition July 2012. PDF
- Kuroda A, Yasuda T, Takahara M, et al. Diabetes Technol Ther. 2012;14(11):1077–1080. PMID: 23101953
- Walsh J. Pumping Everything for Success on an Insulin Pump. San Diego, CA: Torrey Pines Press; 2016.
Testing new basal rates and making adjustments (practical workflow)
Big picture
- Basal testing asks: “If I remove food and bolus variables, does glucose stay reasonably steady?”
- Many pump teaching materials suggest testing when the patient has had a stable prior day (no illness, unusual exercise, major highs/lows) and starting the test in a safe range.
- Pregnancy is different: tighter targets and lower hypoglycemia tolerance → use extra caution and coordinate with your diabetes-in-pregnancy team.
How to do a basal test (step-by-step)
- Pick a “quiet” day: Avoid illness and unusual exercise/stress; make sure the infusion site is working and supplies are available.
- Separate basal from bolus: Wait ~4 hours after the last meal/snack and bolus; avoid very high-fat meals beforehand if delayed rises are common.
- Start in a safe range: If glucose is low, treat and stop; if very high, correct and postpone.
- Avoid confounders: During the test window, avoid carbs and avoid correction boluses unless safety requires stopping.
- Check frequently: Overnight commonly every 2–3 hours; daytime often every 1–2 hours during the chosen window.
- Stop rules: If hypoglycemia occurs, treat and stop; if above your clinic’s “too high” threshold, stop and correct per plan.
Example testing plan (split into “parts of the day”)
A common approach is to test one time-block per day rather than multiple blocks at once:
- Overnight (after dinner bolus is out of action)
- Morning → lunch
- Lunch → dinner
- Dinner → bedtime
Many toolkits emphasize adjusting basal settings first, then refining ISF and ICR.
How to interpret results and adjust basal rates (pregnancy-aware)
- Look for a pattern (not a single reading): repeat a similar test on 2–3 comparable days if feasible.
- Signals that basal may be off: many teaching materials use a rise or fall of ~30–40 mg/dL across the window (assuming no carbs/bolus confounders).
- Change size: a typical starting adjustment is ~10–20% for that segment (or a small absolute change, e.g., 0.05–0.2 U/hr depending on baseline rate and clinical context).
- Timing: adjust the basal segment 1–2 hours before the observed rise/fall (lead time depends on insulin action and profile).
- Safety first: if lows occur, prioritize reducing basal and address contributing factors (activity, site issues, stacked boluses, nausea/poor intake).
- Order of operations: many pump references recommend tuning basal first, then ISF, then ICR.
Basal testing references
Disclaimer
Educational clinician tool. Not a substitute for individualized medical care, device training, or manufacturer labeling. Confirm all settings before use.