{"id":3491,"date":"2026-05-02T11:15:18","date_gmt":"2026-05-02T10:15:18","guid":{"rendered":"https:\/\/livingdiabetes.com\/time-in-range-calculator\/"},"modified":"2026-05-02T11:26:33","modified_gmt":"2026-05-02T10:26:33","slug":"time-in-range-calculator","status":"publish","type":"page","link":"https:\/\/livingdiabetes.com\/ur\/time-in-range-calculator\/","title":{"rendered":"Time-in-Range &#038; GMI Estimator \u2014 Convert CGM Average to HbA1c-Equivalent"},"content":{"rendered":"\n<p><strong>Estimate your Glucose Management Indicator (GMI) and approximate HbA1c from your CGM average.<\/strong> GMI is the modern way to express CGM data in HbA1c-equivalent terms \u2014 a single number you can compare against your last lab HbA1c. Enter your average sensor glucose and the calculator returns the GMI plus your time-in-range targets.<\/p>\n\n\n\n<style>\n.ld-calc{max-width:720px;margin:1.5em 0;padding:1.5em;border:1px solid #d4dde5;border-radius:8px;background:#f8fafc;font-family:inherit}\n.ld-calc h3{margin-top:0;color:#1a4870;font-size:1.25em}\n.ld-row{display:flex;flex-wrap:wrap;gap:.75em;margin-bottom:.85em;align-items:center}\n.ld-row label{flex:1 1 230px;font-weight:600}\n.ld-row input,.ld-row select{flex:0 0 150px;padding:.5em .65em;font-size:1em;border:1px solid #b8c5d3;border-radius:4px;background:#fff}\n.ld-row input:focus,.ld-row select:focus{outline:none;border-color:#1a8cb6;box-shadow:0 0 0 3px rgba(26,140,182,.15)}\n.ld-result{margin-top:1.25em;padding:1em 1.25em;background:#e8f4f9;border-left:4px solid #1a8cb6;border-radius:4px;font-size:1.02em}\n.ld-result .big{font-size:1.4em;font-weight:700;color:#0d5a78;margin-bottom:.4em}\n.ld-result .stat{display:inline-block;margin-right:1.5em}\n.ld-disc{margin-top:1em;padding:.75em 1em;background:#fef9e7;border-left:3px solid #d4a017;border-radius:3px;font-size:.9em}\n@media (max-width:520px){.ld-row label{flex-basis:100%}.ld-row input,.ld-row select{flex-basis:100%}}\n<\/style>\n\n<div class=\"ld-calc\">\n<h3>Time-in-Range &amp; GMI Estimator<\/h3>\n<div class=\"ld-row\"><label for=\"ldt-avg\">Average sensor glucose (last 14 d)<\/label><input type=\"number\" id=\"ldt-avg\" step=\"0.1\" min=\"2\" max=\"30\" placeholder=\"e.g. 8.5\"><\/div>\n<div class=\"ld-row\"><label for=\"ldt-units\">Units<\/label>\n<select id=\"ldt-units\"><option value=\"mmol\">mmol\/L<\/option><option value=\"mg\">mg\/dL<\/option><\/select>\n<\/div>\n<div class=\"ld-row\"><label for=\"ldt-tir\">Time in range (% from CGM, optional)<\/label><input type=\"number\" id=\"ldt-tir\" step=\"1\" min=\"0\" max=\"100\" placeholder=\"e.g. 65\"><\/div>\n<div class=\"ld-row\"><label for=\"ldt-low\">Time below range (%, optional)<\/label><input type=\"number\" id=\"ldt-low\" step=\"0.1\" min=\"0\" max=\"100\" placeholder=\"e.g. 2.5\"><\/div>\n<div class=\"ld-row\"><label for=\"ldt-population\">Population<\/label>\n<select id=\"ldt-population\"><option value=\"adult-t1t2\">Adult \u2014 type 1 or type 2 (general)<\/option><option value=\"adult-frail\">Older adult \/ frail \/ high-risk<\/option><option value=\"pregnancy\">Pregnancy with type 1 diabetes<\/option><\/select>\n<\/div>\n<div class=\"ld-result\" id=\"ldt-out\" style=\"display:none\"><\/div>\n<div class=\"ld-disc\">GMI is a CGM-derived estimate. It can differ from your laboratory HbA1c by up to 0.5%. Use both, not one instead of the other.<\/div>\n<\/div>\n\n<script>\n(function(){\nfunction compute(){\nvar avg=parseFloat(document.getElementById('ldt-avg').value);\nvar units=document.getElementById('ldt-units').value;\nvar tir=parseFloat(document.getElementById('ldt-tir').value);\nvar low=parseFloat(document.getElementById('ldt-low').value);\nvar pop=document.getElementById('ldt-population').value;\nif(!avg)return;\n\/\/ GMI formula (Bergenstal 2018):\n\/\/ GMI(%) = 3.31 + 0.02392 * mean glucose (mg\/dL)\n\/\/ or GMI(%) = 12.71 + 4.70587 * mean glucose (mmol\/L) \u2192 wait that's wrong; use mg\/dL form and convert\nvar avg_mg = units==='mmol' ? avg*18.018 : avg;\nvar avg_mmol = units==='mmol' ? avg : avg\/18.018;\nvar gmi_pct = 3.31 + 0.02392*avg_mg;\nvar gmi_mmol = (gmi_pct - 2.152) \/ 0.09148;  \/\/ IFCC\n\/\/ Targets per population\nvar targets;\nif(pop==='adult-t1t2'){targets={tir:'>70%','>10':'<25%','>13.9':'<5%','<3.9':'<4%','<3':'<1%',label:'Adult type 1 \/ type 2 (Battelino 2019 international consensus)'};}\nelse if(pop==='adult-frail'){targets={tir:'>50%','>10':'(no formal target)','>13.9':'<10%','<3.9':'<1%','<3':'<1%',label:'Older \/ frail \/ high-hypo-risk adults'};}\nelse{targets={tir:'>70% (3.5\u20137.8 mmol\/L)','>10':'<25% (>7.8 mmol\/L)','>13.9':'(rare)','<3.9':'<4%','<3':'<1%',label:'Pregnancy with type 1 diabetes \u2014 note tighter target range 3.5\u20137.8 mmol\/L'};}\nvar assess='';\nif(tir){\nvar t=parseFloat(tir);\nif(t>=70)assess='At-target time-in-range. ';\nelse if(t>=50)assess='Below international target but still meaningful for older \/ frail adults. ';\nelse assess='Below recommended target. ';\n}\nif(low&&parseFloat(low)>4)assess += 'Time below range is above the 4% safety target \u2014 discuss reducing hypoglycaemia risk with your team. ';\nvar html='<div class=\"big\">GMI '+gmi_pct.toFixed(1)+'%  \u2248  '+Math.round(gmi_mmol)+' mmol\/mol<\/div>'+\n'<div><span class=\"stat\"><strong>Average glucose:<\/strong> '+avg_mmol.toFixed(1)+' mmol\/L \/ '+Math.round(avg_mg)+' mg\/dL<\/span><\/div>'+\n'<div style=\"margin-top:.6em;font-size:.95em\"><strong>Targets \u2014 '+targets.label+':<\/strong><ul style=\"margin:.4em 0 0 1.2em;padding:0\">'+\n'<li>Time in range: '+targets.tir+'<\/li>'+\n'<li>Time above 10 mmol\/L: '+targets['>10']+'<\/li>'+\n'<li>Time above 13.9 mmol\/L: '+targets['>13.9']+'<\/li>'+\n'<li>Time below 3.9 mmol\/L: '+targets['<3.9']+'<\/li>'+\n'<li>Time below 3.0 mmol\/L: '+targets['<3']+'<\/li><\/ul><\/div>';\nif(assess)html+='<div style=\"margin-top:.6em;font-style:italic\">'+assess+'<\/div>';\ndocument.getElementById('ldt-out').innerHTML=html;\ndocument.getElementById('ldt-out').style.display='block';\n}\n['ldt-avg','ldt-units','ldt-tir','ldt-low','ldt-population'].forEach(function(id){\ndocument.getElementById(id).addEventListener('input',compute);\ndocument.getElementById(id).addEventListener('change',compute);\n});\n})();\n<\/script>\n\n\n\n<h2 class=\"wp-block-heading\">What GMI is \u2014 and isn&#8217;t<\/h2>\n\n\n\n<p>The Glucose Management Indicator (GMI) is a CGM-derived number that <em>looks like<\/em> HbA1c but is calculated entirely from sensor glucose data. The formula was published by Bergenstal et al. in 2018:<\/p>\n\n\n\n<p><strong>GMI (%) = 3.31 + 0.02392 \u00d7 mean glucose (mg\/dL)<\/strong><\/p>\n\n\n\n<p>It&#8217;s <em>not<\/em> the same as a laboratory HbA1c \u2014 the two can differ by up to 0.5%. The reasons include the contribution of pre-CGM-era data baked into HbA1c, individual variability in red-blood-cell turnover, and any condition that distorts HbA1c (anaemia, transfusion, haemoglobinopathies, kidney disease, pregnancy).<\/p>\n\n\n\n<p>Use both. If they consistently disagree, your team will want to know why.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">The TIR targets used here<\/h2>\n\n\n\n<p>Targets come from the 2019 international consensus on time-in-range (Battelino et al., <em>Diabetes Care<\/em> 2019) and are now incorporated into NICE, ADA, and EASD guidance.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Population<\/th><th>TIR (3.9\u201310 mmol\/L)<\/th><th>Below range (&lt;3.9)<\/th><th>Severe low (&lt;3.0)<\/th><\/tr><\/thead><tbody>\n<tr><td>Type 1 \/ Type 2 adults<\/td><td>&gt; 70%<\/td><td>&lt; 4%<\/td><td>&lt; 1%<\/td><\/tr>\n<tr><td>Older \/ high-risk<\/td><td>&gt; 50%<\/td><td>&lt; 1%<\/td><td>&lt; 1%<\/td><\/tr>\n<tr><td>Pregnancy with T1D<\/td><td>&gt; 70% (target 3.5\u20137.8 mmol\/L)<\/td><td>&lt; 4%<\/td><td>&lt; 1%<\/td><\/tr>\n<\/tbody><\/table><\/figure>\n\n\n\n<p>Each 5% improvement in TIR is associated with a meaningful reduction in long-term complication risk in observational data \u2014 though the strongest evidence still comes from HbA1c-based trials.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">FAQ<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Why does my GMI differ from my last HbA1c?<\/h3>\n\n\n\n<p>Several reasons: HbA1c reflects 8\u201312 weeks while GMI usually reflects the last 14 days; HbA1c is influenced by red-cell lifespan, anaemia, kidney disease, pregnancy, and some haemoglobin variants; and CGMs themselves have a small bias (typically \u00b15%) compared with venous plasma glucose. A persistent gap of more than 0.5% is worth discussing with your team.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">How long should my CGM data be averaged over?<\/h3>\n\n\n\n<p>The international consensus recommends 14 days of data with at least 70% sensor wear time. Most pump and CGM apps show this directly in the AGP (Ambulatory Glucose Profile) report.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Is high TIR more important than low HbA1c?<\/h3>\n\n\n\n<p>They tell complementary stories. HbA1c is a single number tied to long-term complication trials. TIR shows where in the day glucose is escaping target \u2014 useful for treatment adjustment. Most clinicians now use both together.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Related<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/livingdiabetes.com\/hba1c-calculator\/\">HbA1c \u2192 eAG Converter<\/a><\/li>\n<li><a href=\"https:\/\/livingdiabetes.com\/glucose-unit-converter\/\">Glucose Unit Converter<\/a><\/li>\n<li><a href=\"https:\/\/livingdiabetes.com\/calculators\/\">All diabetes calculators<\/a><\/li>\n<\/ul>\n\n\n\n<p><em>References: Bergenstal RM et al. Glucose Management Indicator. Diabetes Care 2018;41:2275-2280. Battelino T et al. Clinical targets for continuous glucose monitoring data interpretation: recommendations from the international consensus on time in range. Diabetes Care 2019;42:1593-1603. ADA Standards of Care 2026. Reviewed: May 2026.<\/em><\/p>\n\n","protected":false},"excerpt":{"rendered":"<p>Estimate Glucose Management Indicator (GMI) and HbA1c-equivalent from your CGM 14-day average. Includes time-in-range targets for type 1, type 2, frail adults, and pregnancy.<\/p>","protected":false},"author":4,"featured_media":3510,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"class_list":["post-3491","page","type-page","status-publish","has-post-thumbnail","hentry"],"rttpg_featured_image_url":{"full":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range.png",1200,630,false],"landscape":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range.png",1200,630,false],"portraits":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range.png",1200,630,false],"thumbnail":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range-150x150.png",150,150,true],"medium":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range-300x158.png",300,158,true],"large":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range-1024x538.png",640,336,true],"1536x1536":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range.png",1200,630,false],"2048x2048":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range.png",1200,630,false],"trp-custom-language-flag":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range-18x9.png",18,9,true],"post-thumbnail":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range-300x158.png",300,158,true],"minimalistblogger-grid":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range-350x230.png",350,230,true],"minimalistblogger-slider":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range-850x446.png",850,446,true],"minimalistblogger-small":["https:\/\/livingdiabetes.com\/wp-content\/uploads\/2026\/05\/og_time-in-range-300x180.png",300,180,true]},"rttpg_author":{"display_name":"Claude SEO","author_link":"https:\/\/livingdiabetes.com\/ur\/author\/claude-seo\/"},"rttpg_comment":0,"rttpg_category":null,"rttpg_excerpt":"Estimate Glucose Management Indicator (GMI) and HbA1c-equivalent from your CGM 14-day average. Includes time-in-range targets for type 1, type 2, frail adults, and pregnancy.","_links":{"self":[{"href":"https:\/\/livingdiabetes.com\/ur\/wp-json\/wp\/v2\/pages\/3491","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/livingdiabetes.com\/ur\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/livingdiabetes.com\/ur\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/livingdiabetes.com\/ur\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/livingdiabetes.com\/ur\/wp-json\/wp\/v2\/comments?post=3491"}],"version-history":[{"count":1,"href":"https:\/\/livingdiabetes.com\/ur\/wp-json\/wp\/v2\/pages\/3491\/revisions"}],"predecessor-version":[{"id":3511,"href":"https:\/\/livingdiabetes.com\/ur\/wp-json\/wp\/v2\/pages\/3491\/revisions\/3511"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/livingdiabetes.com\/ur\/wp-json\/wp\/v2\/media\/3510"}],"wp:attachment":[{"href":"https:\/\/livingdiabetes.com\/ur\/wp-json\/wp\/v2\/media?parent=3491"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}