CGM vs SMBG for Type 1 Diabetes on MDI
STEP 1 — Gather Information
Confirm type 1 diabetes diagnosis and current multiple daily injection (MDI) regimen; assess hypoglycemia history (frequency, severity, nocturnal events), hypoglycemia awareness, patient’s ability/willingness to use CGM (dexterity, visual/hearing for alerts), insurance coverage/access, and need for structured education on device use and data interpretation.
STEP 2 — Rule In / Rule Out
Rule out CGM if the patient cannot safely operate the device (e.g., severe dexterity impairment, uncontrolled dermatitis, lack of training resources, or explicit refusal); otherwise rule in for CGM consideration.
STEP 3 — Classify or Stratify
Stratify by hypoglycemia risk: high (history of severe hypoglycemia requiring assistance, hypoglycemia unawareness, frequent nocturnal events) versus moderate (no severe events but suboptimal glycemic control); prioritize CGM for high‑risk patients.
STEP 4 — Decide
Recommend initiating real‑time CGM (or intermittently scanned CGM with predictive alerts) rather than SMBG alone; provide structured education on device use, troubleshooting, and data interpretation; retain access to SMBG for calibration/validation and sensor warm‑up periods.
Clinical Guardrails / Mimics / Pitfalls
Do not rely solely on CGM values for insulin dosing without confirmatory SMBG during sensor warm‑up, when symptoms mismatch sensor readings, or if sensor malfunctions; do not omit structured education; do not use CGM in patients with substances that interfere with sensor accuracy (e.g., high‑dose vitamin C, hydroxyurea) without verification; do not assume CGM eliminates the need for SMBG entirely.
Concrete Clinical Example
A 22‑year‑old college student with T1D on MDI (glargine basal, lispro bolus) reports two nocturnal hypoglycemia episodes requiring assistance in the past month and fears hypoglycemia disrupting sleep; after confirming MDI regimen and hypoglycemia risk, CGM is initiated with education, and SMBG is retained for calibration and symptom‑sensor mismatches.
Source: Management of Individuals With Diabetes at High Risk for Hypoglycemia: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2023, https://doi.org/10.1210/clinem/dgac596