Glucose management indicator, or GMI, estimates an A1C-like value from mean CGM glucose. It is calculated from sensor data and may differ from laboratory HbA1c, so discordance should be interpreted rather than assuming the two values are interchangeable.
HbA1c and CGM: When Glycemic Control Needs More Than One Number
A peer-level look at how endocrinologists and diabetes specialists interpret HbA1c alongside continuous glucose monitoring: when time in range, hypoglycemia, glycemic variability, and glucose patterns change the treatment decision..
Audience: Endocrinologists
Countries: 6
Completion Rate: 75.7%
SGID: 8975620
-Hero findings
– Quick Read — Key Findings
54.2%
HbA1c is increasingly read alongside other metrics
For most respondents, HbA1c still matters, but its role is becoming more contextual rather than isolated.
66.1%
Range patterns lead interpretation
When HbA1c and CGM diverge, TIR/TBR/TAR and glucose patterns carry the greatest weight.
49.2%
Time in range leads day-to-day use
TIR is the single most selected actionable measure, while AGP and range metrics add pattern detail.
62.7%
Insulin-treated diabetes stands out
Type 1 diabetes and insulin-treated type 2 diabetes are the group in which CGM has most changed glycemic assessment.
43.1%
Incomplete data or adherence leads
Data gaps and patient adherence slightly outrank access, reimbursement, or interoperability as practical constraints.
61.4%
Integration, not replacement, leads
Respondents most often expect wider CGM use and greater integration of range metrics with HbA1c.
When HbA1c and CGM disagree, which signal should drive the decision?
Glycemic control now has an average and a pattern
HbA1c remains central to diabetes care, but CGM can reveal the timing, direction, and variability behind an average that may otherwise look reassuring.
The 2026 American Diabetes Association Standards of Care recommend assessing glycemic status with A1C and/or CGM metrics such as time in range, time above range, and time below range, and for insulin-treated diabetes or hypoglycemia risk, CGM adds information a periodic average cannot show. The MDForLives survey asks a narrower question: when both are available, what do endocrinologists weight most? The answer is not that HbA1c is disappearing, but that it is increasingly read beside glucose patterns, hypoglycemia, variability, and the patient context in which those signals occur.
HbA1c still matters, but most clinicians are no longer reading it alone
54.2% say HbA1c remains important but is increasingly interpreted alongside other measures.
The largest group does not call HbA1c obsolete; they treat it as one part of a broader assessment, while 28.8% still use it as the primary measure for most decisions and 13.6% say CGM metrics can matter more in selected patients. The distinction is practical: HbA1c summarizes longer-term exposure, while CGM adds the daily pattern, when glucose is in range, when lows occur, when highs cluster, and how much it fluctuates. Endocrinology is increasingly using the two views together rather than as competing endpoints.
When HbA1c and CGM diverge, clinicians look first at the glucose pattern
66.1% say TIR/TBR/TAR and glycemic patterns most influence their interpretation when HbA1c and CGM-derived measures appear discordant.
Hypoglycemia and glycemic variability come next at 18.6%, then GMI or mean glucose at 10.2% and symptoms or clinical context at 5.1%. So discordance is rarely resolved by picking another average; clinicians move toward range and timing instead. That matters because the same HbA1c can sit above very different profiles: a patient may spend substantial time both low and high, or show pronounced post-meal excursions, while the average compresses those extremes into one number.
Time in range leads, but clinicians still need the full glucose story
49.2% identify time in range as the single most clinically actionable CGM-derived measure in day-to-day diabetes practice.
AGP and overall pattern analysis rank second at 20.3%, followed by time below or above range at 18.6% and glycemic variability at 11.9%. TIR is the clearest single signal, but the spread shows why a dashboard helps: no one metric explains every decision. CGM has changed assessment most in type 1 or insulin-treated type 2 diabetes (62.7%), followed by recurrent or unrecognized hypoglycemia and marked variability, aligning its value with situations where timing and safety matter as much as the average.
An acceptable HbA1c does not stop treatment changes when CGM exposes risk
66.7% are likely to modify treatment when HbA1c appears acceptable but CGM reveals significant variability or hypoglycemia.
Another 26.3% modify treatment selectively by severity and context, and only 7.0% usually monitor the pattern first; consistent with this, 57.9% say CGM findings frequently or very frequently prompt a change they might not have made from HbA1c alone. Individualization still anchors the decision: 50.0% give greatest weight to hypoglycemia risk plus the current A1C/CGM profile, and 36.2% to age, frailty, cognitive status, or life expectancy, so CGM acts as decision context, not an automatic trigger.
The next CGM challenge is making the data usable, not collecting more
43.1% select incomplete CGM data or patient adherence as a barrier to effective routine use, while 39.7% select access, reimbursement, or interoperability limitations.
Because respondents could pick up to two challenges, these barriers often coexist: incomplete data alongside limited time to interpret it, or a clear need for CGM alongside difficulty sustaining access or moving data into the workflow. Looking ahead, 61.4% expect wider CGM use and tighter integration of TIR/TBR/TAR with HbA1c to change assessment most over the next two to three years, so the opportunity is less about more sensors than about making the growing stream of glucose data easier to interpret, integrate, and act on.
HbA1c stays the anchor; CGM increasingly supplies the pattern behind the decision
The survey does not describe HbA1c being replaced; it describes a more layered form of glycemic assessment. Most respondents still consider HbA1c important, but when the average and the CGM story diverge, range patterns, hypoglycemia, and variability move to the foreground.
For endocrinologists and diabetes specialists, the challenge is now interpretation. The value of CGM depends on enough usable data, access that can be sustained, a workflow that can absorb the information, and judgment that can turn a pattern into the right action for the individual patient.
Endocrinology, Diabetes & Metabolism
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Frequently asked questions
Direct answers to common questions around this topic.
What is the difference between HbA1c and CGM?
HbA1c estimates average glycemic exposure over the preceding two to three months. CGM provides near-continuous glucose data that can show time in range, time below and above range, variability, and daily glucose patterns. They provide different but complementary views of glycemic control.
What does time in range mean in diabetes care?
Time in range is the percentage of CGM readings that fall within a defined target glucose range. It is interpreted alongside time below range, time above range, mean glucose, variability, and the individual patient context.
Can HbA1c be acceptable while CGM shows hypoglycemia?
Yes. HbA1c is an average and may not reveal when low and high glucose values offset each other. CGM can identify the timing and frequency of hypoglycemia even when HbA1c appears to be within an individualized target.
When can CGM data change diabetes treatment?
CGM can influence treatment when it reveals hypoglycemia, hyperglycemia, post-meal excursions, overnight patterns, or variability that are not evident from HbA1c alone. Any change still depends on severity, treatment type, safety, and the individual clinical context.
What is GMI and how is it different from HbA1c?
How much CGM data is usually needed to interpret glucose patterns?
The international CGM consensus and ADA guidance commonly use about 10 to 14 days of data with adequate sensor wear for pattern assessment. Data sufficiency, representativeness, and the patient’s circumstances should be considered before acting on the profile.
Direct answers to the questions healthcare professionals are most likely to ask about these findings.


