Annually reassess use of SMBG to calibrate CGM

STEP 1 — Gather Information

Collect SMBG calibration frequency and timing, calibration log entries, sensor accuracy alerts, hypoglycemia/hyperglycemia events, patient-reported barriers (vision, dexterity, cognition), insurance coverage for strips, and current CGM model calibration requirements.

STEP 2 — Rule In / Rule Out

Is the patient performing SMBG calibration at least once per day (or per manufacturer’s recommendation) for the CGM system?

• Yes → Rule In: adequate calibration practice.
• No → Rule Out: inadequate calibration practice.

STEP 3 — Classify or Stratify

If Rule In: assess ability to make insulin adjustments based on CGM trend information (trend‑based dosing competence).
If Rule Out: classify barriers into cognitive/physical, insurance/access, or knowledge/behavioral deficits.

STEP 4 — Decide

• If Rule In and trend‑based dosing competent: continue current CGM use with annual reassessment.
• If Rule In but trend‑based dosing deficient: provide targeted education on interpreting CGM trends and adjusting insulin.
• If Rule Out: address specific barriers (e.g., simplify SMBG routine, assist with strip access, consider factory‑calibrated CGM if appropriate, reinforce calibration training).

Clinical Guardrails / Mimics / Pitfalls

Do not assume calibration adequacy without reviewing logs; do not rely solely on CGM for therapy decisions on devices requiring calibration; do not discontinue SMBG without confirming the CGM is factory‑calibrated; do not overlook sensor site irritation that may deter SMBG; avoid alarm fatigue by ensuring alerts are appropriately set.

Concrete Clinical Example

A 58‑year‑old with T1D using a Dexcom G6 (requires calibration) presents for yearly review. Log shows SMBG calibration twice weekly, missing daily calibrations. Patient reports finger‑stick pain and forgetfulness. After Rule Out, barriers classified as behavioral/physical. Decision: switch to a factory‑calibrated CGM (Freestyle Libre 3) and provide brief SMBG refresher for occasional confirmation.

Source: Diabetes Technology—Continuous Subcutaneous Insulin Infusion Therapy and Continuous Glucose Monitoring in Adults: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2016, DOI:10.1210/jc.2016-2534