{"doi":"10.2337/dc23-1177","title":"Estimating Glycemia From HbA1c and CGM: Analysis of Accuracy and Sources of Discrepancy","abstract":"OBJECTIVE: To examine the accuracy of different periods of continuous glucose monitoring (CGM), hemoglobin A1c (HbA1c), and their combination for estimating mean glycemia over 90 days (AG90). RESEARCH DESIGN AND METHODS: We retrospectively studied 985 CGM periods of 90 days with <10% missing data from 315 adults (86% of whom had type 1 diabetes) with paired HbA1c measurements. The impact of mean red blood cell age as a proxy for nonglycemic effects on HbA1c was estimated using published theoretical models and in comparison with empirical data. Given the lack of a gold standard measurement for AG90, we applied correction methods to generate a reference (eAG90) that we used to assess accuracy for HbA1c and CGM. RESULTS: Using 14 days of CGM at the end of the 90-day period resulted in a mean absolute error (95th percentile) of 14 (34) mg/dL when compared with eAG90. Nonglycemic effects on HbA1c led to a mean absolute error for average glucose calculated from HbA1c of 12 (29) mg/dL. Combining 14 days of CGM with HbA1c reduced the error to 10 (26) mg/dL. Mismatches between CGM and HbA1c >40 mg/dL occurred more than 5% of the time. CONCLUSIONS: The accuracy of estimates of eAG90 from limited periods of CGM can be improved by averaging with an HbA1c-based estimate or extending the monitoring period beyond ∼26 days. Large mismatches between eAG90 estimated from CGM and HbA1c are not unusual and may persist due to stable nonglycemic factors.","journal":"Diabetes Care","year":2024,"id":430126,"datarank":0.4566783656585135,"base_score":3.044522437723423,"endowment":3.044522437723423,"self_citation_contribution":0.4566783656585135,"citation_network_contribution":0.0,"self_endowment_contribution":0.4566783656585135,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":20,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.91,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1233600,"name":"Matthew Genco","orcid":null,"position":1,"is_corresponding":false},{"id":975058,"name":"Shammah O. Omololu","orcid":"0000-0002-9579-5920","position":2,"is_corresponding":false},{"id":1203876,"name":"Christopher Mow","orcid":"0000-0003-4862-9230","position":3,"is_corresponding":false},{"id":1204771,"name":"Hasmukh Patel","orcid":null,"position":4,"is_corresponding":false},{"id":1204772,"name":"Chhaya H. Patel","orcid":null,"position":5,"is_corresponding":false},{"id":1204773,"name":"Samantha N. Ho","orcid":null,"position":6,"is_corresponding":false},{"id":1204774,"name":"Evie Lam","orcid":null,"position":7,"is_corresponding":false},{"id":1233601,"name":"Batoul Abdulsater","orcid":null,"position":8,"is_corresponding":false},{"id":86923,"name":"Nikita Patel","orcid":null,"position":9,"is_corresponding":false},{"id":738640,"name":"Robert M. Cohen","orcid":"0000-0002-3164-5843","position":10,"is_corresponding":false},{"id":16013,"name":"David M. Nathan","orcid":null,"position":11,"is_corresponding":false},{"id":307952,"name":"Camille E. Powe","orcid":"0000-0002-7060-7778","position":12,"is_corresponding":false},{"id":251965,"name":"Deborah J. Wexler","orcid":"0000-0001-6979-402X","position":13,"is_corresponding":false},{"id":337769,"name":"John M. Higgins","orcid":"0000-0002-9182-0076","position":14,"is_corresponding":false},{"id":400585,"name":"Veronica Tozzo","orcid":"0000-0001-8538-9198","position":0,"is_corresponding":true}],"reference_count":33,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-19T01:59:16.092672Z","pmid":"38394636","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}