Avoid single 24-hour CGM target in pregnancy with preexisting diabetes

STEP 1 — Gather Information

Collect: pregnancy confirmation, diabetes type (T1DM/T2DM), gestational age, current CGM metrics, proposed glucose target (e.g., single 24‑hour CGM target <140 mg/dL), maternal hypoglycemia history. Action: If data incomplete, obtain missing information before proceeding.

STEP 2 — Rule In / Rule Out

Is the clinician considering replacing standard pregnancy glucose targets with a single 24‑hour CGM target <140 mg/dL?

• Yes → proceed to Step 3 (rule out the single target).
• No → continue with standard targets; no further action needed for this skill.

STEP 3 — Classify or Stratify

Assess for safety of standard targets: check for history of severe hypoglycemia, hypoglycemia unawareness, or tight control that may increase risk.

• If no contraindications → classify as appropriate for standard targets.
• If contraindications present → flag for individualized targets (e.g., higher fasting threshold) and involve maternal‑fetal medicine; then proceed to Step 4 with adjusted targets.

STEP 4 — Decide

Recommend using the standard pregnancy glucose targets (fasting <95 mg/dL, 1‑hour postprandial <140 mg/dL, 2‑hour postprandial <120 mg/dL) for CGM‑guided management instead of a single 24‑hour target <140 mg/dL. Document the decision and educate the patient on target‑based insulin adjustments.

Clinical Guardrails / Mimics / Pitfalls

Do not use a single 24‑hour CGM target <140 mg/dL as a substitute for fasting and postprandial targets; avoid over‑reliance on time‑in‑range alone; be aware that hybrid closed‑loop algorithms may not achieve all three targets simultaneously; monitor for hypoglycemia when applying tight targets; consider individualized adjustments if maternal hypoglycemia occurs.

Concrete Clinical Example

A 32‑year‑old with type 1 diabetes at 18 weeks gestation plans to use CGM. The clinician initially considers a simple target of “keep glucose <140 mg/dL all day.” After gathering information (no hypoglycemia history, gestational age 18w), the rule‑out step triggers, classification finds no contraindications, and the decision is to advise fasting <95, 1‑hour <140, 2‑hour <120 mg/dL targets, with insulin adjustments based on pre‑meal and post‑meal readings.

Source: Preexisting Diabetes and Pregnancy: An Endocrine Society and European Society of Endocrinology Joint Clinical Practice Guideline, Endocrine Society and European Society of Endocrinology, 2025, DOI: 10.1210/clinem/dgaf288

TODO: consider adding scripts/calc.py for the pdm-cgm-targets calculator