Health Problem: Diabetes mellitus (DM or diabetes) is a chronic, progressive disease characterized by impaired metabolism of carbohydrates. This disorder manifests in 2 main forms: type 1 DM and type 2 DM. Type 1 DM typically manifests during childhood and adolescence but can also develop in adults. Type 1 DM accounts for < 10% of cases and stems from the lack of production of the hormone insulin resulting from autoimmune destruction of beta cells in the pancreas. In contrast, type 2 DM, which accounts for 90% of cases of diabetes, is a result of inadequate insulin secretion because patients have developed resistance to insulin. The pathogenesis of type 2 DM is complex and not completely understood.

Technology Description:  Continuous glucose monitoring (CGM) systems are minimally invasive devices that measure glucose in interstitial fluid at predetermined intervals; these measurements assist in determining the appropriate insulin dosage required to achieve glycemic control in a diabetic patient. The FreeStyle Libre Flash Glucose Monitoring (FGM) system is an intermittently scanned CGM system. It is the first CGM system approved by the Food and Drug Administration as a stand-alone device for monitoring blood glucose levels, eliminating the need for frequent self-monitored blood glucose (SMBG) by finger stick blood testing. The FreeStyle Libre system is comprised of a sensor applicator, factory-calibrated sensor, and reader. The sensor is applied to the back of the upper arm and held in place by an adhesive.

Controversy: People with DM need to measure blood glucose levels several times a day for optimal management of disease and prevention of future complications. This process requires finger sticks to draw blood and subsequent testing with a glucose meter. The process causes pain and is inconvenient; thus, patient compliance is an issue. Also, SMBG only provides the blood glucose level at the moment of the test, which can result in some degree of undetected hypoglycemia or hyperglycemia. The FreeStyle Libre FGM system measures interstitial glucose levels every minute, providing glucose levels and trends to the user so that insulin adjustments can be made before blood glucose is out of range. In addition, the FreeStyle Libre system is factory calibrated and does not require SMBG calibration.

Key Questions:

  • Does the FreeStyle Libre FGM system accurately measure glucose levels in interstitial fluid in adults with DM?
  • Does the information obtained from the FreeStyle Libre FGM system improve short-term glycemic outcomes and long-term health outcomes in adults with DM?
  • How does the FreeStyle Libre FGM system compare with alternative methods of glucose monitoring (e.g., capillary blood glucose measurements, other CGM systems)?
  • Is the FreeStyle Libre FGM system safe?
  • Have definitive patient selection criteria been identified for the FreeStyle Libre FGM system?

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