BC ADM Blood Glucose Monitoring 5 — Questions and Answers
Question 1: A pregnant patient with pre-existing T1D is using CGM. What is the recommended TIR target during pregnancy according to international consensus guidelines?
- >70% TIR (63–140 mg/dL) (Correct answer)
- >80% TIR (70–180 mg/dL)
- >65% TIR (63–140 mg/dL)
- >75% TIR (70–180 mg/dL)
Correct answer: >70% TIR (63–140 mg/dL)
Pregnancy CGM consensus recommends >70% TIR using a tighter target range of 63–140 mg/dL due to the risks of fetal macrosomia from maternal hyperglycemia.
Question 2: Which factor most commonly causes a CGM sensor to fail prematurely before its wear period ends?
- Excessive hydration
- Physical displacement or compression of the sensor at the insertion site (Correct answer)
- Cold weather below 32°F
- High-protein diet
Correct answer: Physical displacement or compression of the sensor at the insertion site
Physical compression or displacement of the CGM sensor at the insertion site (e.g., sleeping on the sensor, trauma) is the most common cause of premature sensor failure.
Question 3: A patient with CKD stage 4 on erythropoietin therapy has an A1C of 6.4% but CGM shows average glucose of 185 mg/dL. What explains this discordance?
- CGM is inaccurate in CKD patients
- Erythropoietin increases red blood cell turnover, shortening RBC lifespan and falsely lowering A1C (Correct answer)
- High creatinine interferes with A1C measurement
- CKD causes accelerated glycation of hemoglobin
Correct answer: Erythropoietin increases red blood cell turnover, shortening RBC lifespan and falsely lowering A1C
Erythropoietin stimulates new RBC production with shorter lifespans, reducing A1C's validity as it reflects less glycation time, making CGM-derived average glucose more reliable.
Question 4: When reviewing structured SMBG data, a pattern of elevated fasting glucose (>130 mg/dL) despite normal bedtime readings (100–120 mg/dL) most likely indicates:
- Somogyi effect (rebound hyperglycemia from nocturnal hypoglycemia)
- Dawn phenomenon (hepatic glucose output from counter-regulatory hormones in early morning) (Correct answer)
- Incorrect fasting glucose testing technique
- Excessive bedtime snack consumption
Correct answer: Dawn phenomenon (hepatic glucose output from counter-regulatory hormones in early morning)
Normal bedtime glucose rising to elevated fasting without nocturnal hypoglycemia is characteristic of the dawn phenomenon, driven by growth hormone and cortisol surges in early morning.
Question 5: A BC-ADM specialist is evaluating a patient's glucose log showing consistent postprandial spikes to 280–320 mg/dL after breakfast only. What is the most appropriate intervention to investigate first?
- Increase total daily basal insulin dose by 20%
- Evaluate breakfast composition and insulin-to-carbohydrate ratio for the morning meal (Correct answer)
- Switch the patient to premixed insulin
- Order a gastric emptying study
Correct answer: Evaluate breakfast composition and insulin-to-carbohydrate ratio for the morning meal
Isolated postprandial spikes after a specific meal suggest the mealtime insulin-to-carbohydrate ratio is inadequate for that meal's composition, requiring dietary review and ratio adjustment.
Question 6: Which international consensus document established the standardized CGM metrics (TIR, TBR, TAR, CV, GMI) used in clinical practice and research?
- ADA Standards of Medical Care 2019
- International Consensus on Time in Range (Battelino et al., 2019) (Correct answer)
- EASD/ADA Hyperglycemia Management Algorithm 2020
- AACE Diabetes Algorithm 2018
Correct answer: International Consensus on Time in Range (Battelino et al., 2019)
The 2019 International Consensus on Time in Range (Battelino et al.) established standardized CGM metrics and targets that are now universally used in clinical practice and research.
Question 7: A patient using an implantable CGM (Eversense) asks how it differs from transcutaneous CGM systems. Which answer is most accurate?
- Implantable CGM measures blood glucose directly rather than interstitial glucose
- Implantable CGM sensors last 90–180 days and require in-office insertion and removal (Correct answer)
- Implantable CGM does not require a transmitter or mobile app
- Implantable CGM is approved for insulin dosing decisions without fingerstick confirmation
Correct answer: Implantable CGM sensors last 90–180 days and require in-office insertion and removal
Eversense is implanted subcutaneously by a clinician, with sensors lasting 90 days (US) to 180 days (EU), requiring a clinic visit for insertion and removal unlike wearable patch systems.
BC ADM Blood Glucose Monitoring 5
A pregnant patient with pre-existing T1D is using CGM.
What is the recommended TIR target during pregnancy according to international consensus guidelines?