CGM for insulinoma screening: a prospective and observational case-control study

Area of Science:

• Endocrinology
• Oncology
• Medical Diagnostics

Background:

• Insulinoma diagnosis traditionally relies on the 72-hour fasting test (IRI), which requires hospitalization and incurs significant costs.
• There is a critical need for accessible, cost-effective outpatient screening methods for insulinoma.
• Continuous glucose monitoring (CGM) is established for managing hyperglycemia in diabetes.

Purpose of the Study:

• To evaluate the utility of CGM as a screening tool for insulinoma in an outpatient setting.
• To assess the diagnostic performance of CGM-derived metrics for identifying insulinoma.

Main Methods:

• A prospective, single-center study involving 28 insulinoma patients and 25 functional hypoglycemia controls.
• Analysis of continuous glucose monitoring (CGM) data, focusing on the coefficient of variation (CV).
• Receiver operating characteristic (ROC) curve analysis to determine optimal CV cutoff points.

Main Results:

• The coefficient of variation (CV) derived from CGM demonstrated strong diagnostic capability (Area Under Curve = 0.914).
• A CV cutoff of 19% achieved 82.1% sensitivity and 80% specificity for insulinoma screening.
• Higher CV values correlated with insulinomas located in the pancreatic head, elevated Ki-67, and larger tumor size.

Conclusions:

• CGM presents a valuable, non-invasive tool for outpatient insulinoma screening, complementing its use in diabetes management.
• A CV threshold of 19% derived from CGM data is highly effective for identifying patients who require further investigation for insulinoma.