CGM vs A1c debate heats up
Clinicians and analysts are actively debating whether HbA1c or CGM‑derived metrics should be the gold standard for diabetes control, with recent coverage laying out pros and cons of each approach. (medscape.com)
An international consensus published in The Lancet Diabetes & Endocrinology in January 2023 issued 23 recommendations to standardize how continuous glucose monitoring (CGM) data are collected, analyzed and reported in clinical trials and urged that CGM metrics be considered alongside HbA1c by regulators and industry. (thelancet.com) The American Diabetes Association’s 2025 Standards of Care explicitly elevated CGM-derived metrics such as time in range (TIR) into clinical guidance and broadened recommendations to consider CGM for adults with type 2 diabetes treated with non‑insulin glucose‑lowering medications. (timeinrange.org) The U.S. Food and Drug Administration released a draft update in 2023 on diabetes‑trial efficacy endpoints and received coordinated stakeholder submissions urging formal recognition of CGM measures (including TIR) as potential endpoints for antidiabetic drug approvals. (appliedclinicaltrialsonline.com) Laboratory and clinical authorities note concrete limitations of HbA1c: common hemoglobin variants and conditions that change red‑cell lifespan (iron deficiency, hemolysis, chronic kidney disease) can bias results, and multiple analyses have documented race/ethnicity‑linked differences in the A1c–average‑glucose relationship. (ngsp.org) CGM technology also has defined constraints: systematic reviews show reduced point accuracy in hypoglycaemic ranges, regulators and standards bodies call for assessment beyond single‑number MARD metrics, and CLSI’s POCT05 guidance recommends evaluating both point and trend accuracy for clinical use. (journals.sagepub.com) Payer and market shifts are reshaping practical tradeoffs: Medicare expanded CGM coverage effective April 2023 (removing prior multi‑injection rules), advocates estimate ~1.5 million more beneficiaries became eligible, and manufacturers reported reimbursed access expansion to more than 4 million people in recent corporate filings. (medicare.gov) Evidence tying CGM metrics to outcomes is growing but still evolving: systematic reviews and cohort studies report that increases in TIR (commonly cited as 10% increments) associate with lower rates of retinopathy, albuminuria and neuropathy in observational analyses and secondary trial evaluations. (chcs.org)
