# AI programs an insulin pump with a 24-hour basal rate profile that ignores circadian insulin sensitivity, causing nocturnal hypoglycemia and dawn phenomenon hyperglycemia

- **ID:** `medical/insulin-pump-circadian-basal-rate-miss`
- **Domain:** medical
- **Category:** data_error
- **Error Code:** `MED-PUMP-010`
- **Verification:** ai_generated
- **Fix Rate:** 78%

## Root Cause

Circadian insulin sensitivity varies: early morning (dawn phenomenon) requires higher basal rate, while midnight to 3 AM requires lower basal rate to prevent hypoglycemia. AI often uses a flat or incorrectly shaped basal profile, ignoring these physiological patterns.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| Medtronic MiniMed 780G 2.0 | active | — | — |
| Tandem t:slim X2 1.5 | active | — | — |
| Insight 1.4.2 | active | — | — |

## Workarounds

1. **Program a multi-step basal profile with 2-3 hour segments. Example for typical adult: 00:00-03:00: 0.8 U/h, 03:00-06:00: 1.0 U/h, 06:00-09:00: 1.3 U/h, 09:00-12:00: 1.1 U/h, 12:00-18:00: 1.0 U/h, 18:00-24:00: 0.9 U/h. Then fine-tune based on CGM data over 3-5 days.** (88% success)
   ```
   Program a multi-step basal profile with 2-3 hour segments. Example for typical adult: 00:00-03:00: 0.8 U/h, 03:00-06:00: 1.0 U/h, 06:00-09:00: 1.3 U/h, 09:00-12:00: 1.1 U/h, 12:00-18:00: 1.0 U/h, 18:00-24:00: 0.9 U/h. Then fine-tune based on CGM data over 3-5 days.
   ```
2. **Use automated basal rate optimization via hybrid closed-loop algorithm (e.g., Control-IQ or SmartGuard) that adjusts basal every 5 minutes based on CGM trend. This bypasses manual profile errors.** (92% success)
   ```
   Use automated basal rate optimization via hybrid closed-loop algorithm (e.g., Control-IQ or SmartGuard) that adjusts basal every 5 minutes based on CGM trend. This bypasses manual profile errors.
   ```

## Dead Ends

- **Use a single flat basal rate for 24 hours to simplify programming** — Flat rate causes nocturnal hypoglycemia (too high at 2 AM) and morning hyperglycemia (too low at 6 AM) in most patients (80% fail)
- **Set lowest basal rate at midnight and highest at noon, following a simple sine wave** — The physiological nadir is 2-3 AM, not midnight; and peak is 6-8 AM (dawn phenomenon), not noon. A sine wave is too simplistic and mismatches real patterns (65% fail)
- **Use the same basal profile for all patients, adjusting only total daily dose** — Circadian patterns vary significantly between individuals; a one-size-fits-all profile causes poor glycemic control (90% fail)