The changing landscape of glycemic targets: Focus on continuous glucose monitoring

Abstract

Continuous glucose monitoring (CGM) provides comprehensive assessment of daily glucose measurements for patients with diabetes and can reveal high and low blood glucose values that may occur even when a patient's A1C is adequately controlled. Among the measures captured by CGM, the percentage of time in the target glycemic range, or "time in range"(typically 70-180 mg/dL), has emerged as one of the strongest indicators of good glycemic control. This review examines the shift to using CGM to assess glycemic control and guide diabetes treatment decisions, with a focus on time in range as the key metric of glycemic control. For individuals with diabetes, hyperglycemia and hypoglycemia present the greatest risks with regard to developing complications of diabetes, yet many patients are unaware of their daily blood glucose highs and lows. Traditionally, A1C has been the gold standard for assessing glycemic control, and A1C over time has shown a clear association with the development of vascular complications of diabetes (1-4). However, the use of continuous glucose monitoring (CGM) systems to measure interstitial glucose concentrations throughout the day has grown in recent years, supplanting multiple daily finger sticks for many patients and clinicians. This review summarizes the shift to using CGM to guide treatment decisions, with a focus on glycemic time in range (TIR) as the key indicator of glycemic control.