Assess basal settings via basal rate testing
STEP 1 — Gather Information
Collect recent CGM or SMBG glucose profiles (including overnight, pre‑meal, post‑meal), current basal rate schedule, recent hypoglycemia/hyperglycemia events, and confirm patient ability to safely fast for testing periods.
Action: Proceed to assess safety and eligibility for basal rate testing.
STEP 2 — Rule In / Rule Out
Determine if basal rate testing is safe: no recent severe hypoglycemia, patient can monitor glucose frequently, not pregnant or acutely ill, and has rapid‑acting carbohydrate available.
- If unsafe → Rule out basal rate testing; pursue alternative assessment (e.g., review pump downloads, consider sensor‑guided adjustments).
- If safe → Rule in basal rate testing; schedule test periods (typically overnight, pre‑breakfast, pre‑lunch, pre‑dinner).
Action: Either rule out and document rationale, or rule in and prepare for testing.
STEP 3 — Classify or Stratify
Analyze glucose trends during each basal test period to classify pattern:
- Stable (change ≤10 mg/dL) → no adjustment needed.
- Hypoglycemic trend (fall >10 mg/dL) → basal too high.
- Hyperglycemic trend (rise >10 mg/dL) → basal too low.
- Dawn phenomenon (early‑morning rise) → consider increased basal overnight.
Action: Identify basal adjustment direction and magnitude based on observed glucose drift.
STEP 4 — Decide
Adjust basal rates by 10‑20% for the identified periods (decrease for hypoglycemia, increase for hyperglycemia); if stable, hold current rate. Document changes, educate patient on signs of over/under‑basal, and plan follow‑up review.
Action: Implement basal rate adjustment and schedule reassessment in 1‑2 weeks.
Clinical Guardrails / Mimics / Pitfalls
Do not test during illness, alcohol use, or altered basal‑to‑bolus ratios; avoid >20% basal change per adjustment; ensure patient can treat hypoglycemia promptly; confirm basal rates remain physiologic (typically 40‑60% of total daily dose); beware of mistaking post‑prandial effects for basal needs.
Concrete Clinical Example
A 45‑year‑old with T1DM using CSII reports fasting glucose 180 mg/dL; overnight basal test shows a 30 mg/dL rise from 02:00–06:00; increase basal rate 15% during that window; follow‑up shows fasting glucose 130 mg/dL.
Source: Diabetes Technology—Continuous Subcutaneous Insulin Infusion Therapy and Continuous Glucose Monitoring in Adults: An Endocrine Society Clinical Practice Guideline, Anne L. Peters et al., 2016, DOI: 10.1210/jc.2016-2534
TODO: consider adding scripts/calc.py for the endo-assess-basal-settings-rate-testing calculator