Can a patient with a history of polycystic ovary syndrome (PCOS) and reactive hypoglycemia be approved for inpatient admission for continuous glucose monitoring (CGM) due to frequent episodes of low blood glucose?

CGM for Inpatient Admission: Not Indicated for Reactive Hypoglycemia

This patient should NOT be approved for inpatient admission with continuous glucose monitoring (CGM) for reactive hypoglycemia, as CGM is not FDA-approved for inpatient use and the clinical indication does not meet established criteria for inpatient CGM monitoring. 1

Key Regulatory and Clinical Barriers

FDA Approval Status

• CGM devices are NOT FDA-approved for routine inpatient use, despite theoretical advantages in detecting hypoglycemia 1
• The FDA exercised enforcement discretion during COVID-19 to allow temporary CGM use in hospitals, but this was specifically for remote monitoring to reduce personal protective equipment use and staff exposure—not for diagnostic evaluation of reactive hypoglycemia 1, 2, 3
• At the time of current guidelines, CGM remains an investigational system for inpatient use 2

Clinical Indication Mismatch

• The patient does not have diabetes mellitus, which is the fundamental requirement for CGM use according to all major guidelines 1
• Established CGM indications require diabetes (type 1, type 2, or insulin-deficient diabetes) as the first criterion 1
• The patient has reactive hypoglycemia and PCOS—neither condition meets guideline criteria for CGM 1

Appropriate Diagnostic Approach

72-Hour Fasting Test Protocol

• The planned 72-hour fasting test is the gold standard diagnostic approach for evaluating hypoglycemia disorders and does not require CGM technology
• This test uses standard point-of-care (POC) glucose monitoring with hospital-calibrated meters, which remains the approved method for inpatient glucose assessment 1
• POC testing every 4-6 hours (or more frequently as needed during fasting) is the established protocol 1, 4

Why Inpatient CGM Is Not Appropriate Here

• CGM in hospitals is reserved for patients with diabetes on insulin therapy, particularly those at high risk for hypoglycemia during acute illness 1
• The Chinese Clinical Guidelines specify CGM for type 2 diabetes patients with "unexplainable severe hypoglycemia or recurrent hypoglycemia" but only in the context of diabetes treatment 1
• This patient's hypoglycemia is reactive (postprandial), not related to diabetes medications, making CGM criteria inapplicable 1

Alternative Monitoring Strategy

Outpatient CGM Use

• The patient has already successfully used a personal CGM device at home, which has documented glucose values frequently <70 mg/dL
• This outpatient CGM data, combined with glucometer readings, has already confirmed the hypoglycemic episodes and established Whipple's triad 1
• Continuation of personal CGM at home (not during inpatient admission) would be appropriate for ongoing monitoring after diagnosis is established

Proper Inpatient Monitoring

• Standard POC glucose monitoring every 2-4 hours during the 72-hour fast is the appropriate inpatient approach 1, 4
• Hospital-calibrated glucose meters provide the accuracy needed for diagnostic evaluation 1
• Confirmatory laboratory serum glucose measurements should be obtained when critical values are detected 1

Common Pitfalls to Avoid

Misunderstanding CGM Indications

• Do not confuse outpatient CGM criteria with inpatient CGM use—these are entirely different regulatory and clinical contexts 1
• Outpatient CGM for reactive hypoglycemia may be reasonable, but inpatient CGM for this indication is not supported 1

Regulatory Compliance

• Using non-FDA-approved devices for inpatient care creates liability and reimbursement issues 1
• Some hospitals allow personal CGM continuation under specific protocols with diabetes team supervision, but this applies only to patients with established diabetes who are already using CGM at home 1, 5

Diagnostic Accuracy Concerns

• CGM accuracy in the inpatient setting has limitations, with mean absolute relative difference (MARD) of 13-16% compared to standard testing 6
• For diagnostic purposes (rather than diabetes management), POC and laboratory glucose measurements are more appropriate 1, 6

Clinical Recommendation

Deny the request for inpatient admission with CGM. Instead, approve inpatient admission for the 72-hour fasting test using standard POC glucose monitoring protocols. 1 The patient's existing outpatient CGM data has already documented the hypoglycemic episodes; the inpatient fasting test serves to establish the etiology, which requires precise laboratory measurements, not CGM technology. 1