Blood Sugar & Insulin
HbA1c and Healthy Aging
HbA1c tracks blood sugar and predicts heart disease and death. But lower isn't always better, and prediabetes often doesn't progress in older adults.
HbA1c has a name like a license plate and a reputation as the blood test that keeps score. If you track your lab results, it’s probably one you watch, and it’s easy to assume lower always means healthier. For Humanic Blue, the HbA1c and healthy aging story is more complicated, and more interesting, than that.
HbA1c reflects your average blood sugar over the past two to three months. Under American Diabetes Association criteria, below 5.7% is normal, 5.7% to 6.4% is prediabetes and 6.5% or higher meets the threshold for diabetes. In a long-running US study analyzed by Johns Hopkins researchers, higher HbA1c predicted diabetes, heart disease and death, but very low values came with higher death rates too. In ACCORD, a trial in adults with type 2 diabetes and heart disease or other cardiovascular risk factors, an intensive medication strategy targeting near-normal HbA1c increased deaths compared with the standard strategy. No study has set an “optimal” HbA1c for living longer.
In This Article
- What the number actually measures
- Higher HbA1c predicted diabetes, heart disease and death
- Very low HbA1c came with higher death rates, too
- What an intensive treatment trial found in high-risk diabetes
- Prediabetes in your 70s often didn’t progress
- Why diabetes goals loosen with age, and where the experts differ
- The studies and numbers behind all of this
Key Takeaways
- In the ARIC observational study, adults without diabetes who had higher HbA1c were more likely to develop diabetes, heart disease or stroke, or to die during follow-up. That association does not show that the number caused those outcomes.
- Very low HbA1c (below 5.0%) was also linked to higher death rates in that study. The cause remains unclear.
- In ACCORD, an intensive medication strategy targeting near-normal HbA1c increased deaths among people with type 2 diabetes and high cardiovascular risk.
- In one study of adults in their 70s with HbA1c-defined prediabetes, returning to normal HbA1c or dying during follow-up was more common than developing diabetes.
- The American Diabetes Association and American College of Physicians set less stringent goals for many older adults with diabetes, but differ on the target ranges.
What does the HbA1c number measure?
HbA1c measures how much hemoglobin, the oxygen-carrying protein in red blood cells, has glucose stuck to it. Red blood cells live about 120 days, so the American Diabetes Association describes HbA1c as a measure of blood sugar over roughly the past two to three months, weighted toward recent weeks. It isn’t affected by what you ate that morning, so it doesn’t require fasting.
The American Diabetes Association’s (ADA’s) cutoffs, and the conditions that can make the test inaccurate, such as anemia and kidney or liver disease, are covered in Longevity Blood Test Checklist.
HbA1c also drifts up slightly with age in people without diabetes, as covered in Which Blood Tests Change as We Age?
What HbA1c predicts
A number this widely watched deserves a long-running study behind it, and HbA1c has one. In a 2010 New England Journal of Medicine analysis from the Atherosclerosis Risk in Communities (ARIC) study, Elizabeth Selvin and colleagues in the epidemiology department at the Johns Hopkins Bloomberg School of Public Health measured HbA1c in about 11,000 middle-aged Black and white adults. None had diabetes or cardiovascular disease. The researchers followed them for about 14 years. (Note 1)
Higher starting HbA1c was associated with higher risk of diabetes, heart disease and stroke. People between 6.0% and 6.5%, just under the diabetes line, had about 80% higher risk of coronary heart disease than people between 5.0% and 5.5%.
HbA1c also out-predicted fasting glucose, the older standard. The authors concluded that HbA1c tracked the risk of cardiovascular disease and of death from any cause more closely than fasting glucose did. It’s an observational study, so it shows a link, not a cause. The full risk table
What did researchers see at very low HbA1c?
Death rates didn’t keep falling at the bottom of the range. In the same ARIC data, people below 5.0% had about 1.5 times the death rate of people at 5.0% to 5.5%. The pattern held when the researchers set aside people with anemia and deaths in the first few years.
Nobody knows why. The authors called for more study of factors other than blood sugar that might affect HbA1c, since something besides glucose may push the number down in some people.
What happened when a trial pushed it down
The low-end pattern is an observation. A direct test of pushing HbA1c down came in people who already had diabetes. The ACCORD trial, run at 77 centers in the US and Canada and published in the New England Journal of Medicine in 2008, randomly assigned about 10,000 adults with type 2 diabetes and heart disease or other heart risks (average age 62). One group aimed for an HbA1c below 6.0%, the other for 7.0% to 7.9%.
The intensive approach was stopped early, after about 3.5 years, because more people were dying in that group than in the standard-treatment group. It didn’t significantly reduce heart attacks, strokes and heart deaths combined. Low blood sugar serious enough to need someone else’s help, and weight gain of more than 10 kg (about 22 pounds), were both more common with intensive treatment.
The investigators described it as a harm of intensive glucose lowering in high-risk patients with type 2 diabetes that hadn’t been recognized before. The trial was publicly funded; drug and device makers supplied some medications and equipment. (Note 2) How the trial worked
How does ACCORD change the question from predicting risk to testing a treatment target?
Prediabetes in your 70s
The same ARIC study later checked in on its participants in older age. In a 2021 JAMA Internal Medicine analysis, a Johns Hopkins epidemiology team led by Mary Rooney followed about 3,400 adults without diabetes, average age about 76. Almost half, 44%, had prediabetes by HbA1c (5.7% to 6.4%).
Over up to 6.5 years, 9% of that group progressed to diabetes, 13% returned to a normal HbA1c and 19% died. The authors wrote that prediabetes “may not be a robust diagnostic entity in older age.” (Note 3)
The ADA’s own 2026 Standards of Care add a relevant caveat: trials showing that diabetes can be prevented were done mainly in people whose prediabetes was found with a glucose tolerance test, not in people whose prediabetes was defined by HbA1c alone. The progression numbers
What does the older-adult follow-up add to the meaning of a prediabetes label?
Why do diabetes goals loosen with age?
For people who already have type 2 diabetes, two major medical organizations say goals should loosen for many older adults. They differ on how far.
The American College of Physicians. Its 2018 guidance statement tells clinicians to “aim to achieve an HbA1c level between 7% and 8% in most patients.” It advises considering “deintensifying pharmacologic therapy”—reducing the intensity of medication treatment—when HbA1c falls below 6.5%. For people with a life expectancy under 10 years, because of advanced age, nursing-home residence or chronic conditions such as dementia or congestive heart failure, it advises against targeting any HbA1c level “because the harms outweigh the benefits in this population.” (Note 4)
The American Diabetes Association. The ADA also individualizes goals for older adults based on health status. Its 2026 Standards of Care suggest a lower goal, such as below 7.0% to 7.5%, for healthy older adults with few chronic illnesses and intact thinking and function. They suggest below 8.0% for people with more complex health, and for people in very poor health they advise not relying on HbA1c at all. (Note 5)
So for a healthy older adult, the ADA’s suggested goal can sit below the ACP’s 7% to 8% range. Both groups put avoiding low blood sugar ahead of chasing a lower number when health is more fragile. The goals side by side
What’s Interesting
The ACCORD investigators explained the question they wanted to test: if higher HbA1c is linked with heart problems, would more intensive treatment to lower it prevent those problems? In adults with type 2 diabetes and high cardiovascular risk, their intensive strategy increased deaths without significantly reducing the combined rate of heart attacks, strokes and cardiovascular deaths.
That’s the gap between a risk marker and a treatment target: a number can predict risk without every strategy for lowering it improving health. The number is a signal about blood sugar and sometimes about other things too. For a test that works by counting sugar stuck to red blood cells, that’s a fairly philosophical place to land.
What This Means in Practice
For living longer and better, the studies above point to HbA1c as a screening and monitoring tool to read in context, not a score to minimize.
Each finding here comes from a particular group: middle-aged Black and white adults without diabetes in ARIC, high-risk adults with type 2 diabetes in ACCORD, adults in their 70s in the later ARIC analysis. Someone who looks different from those groups, or who has anemia or kidney disease, may find the same number means something different.
- The ADA categories describe different findings. Below 5.7%, 5.7% to 6.4% and 6.5% or higher mean different things under its criteria.
- Lower isn’t automatically better. No trial shows that pushing HbA1c lower in people without diabetes adds years, and ARIC linked values below 5.0% to higher mortality.
- Ask what’s driving an unexpected result. Anemia, kidney disease and other conditions can make HbA1c misleading.
- If you’re older with prediabetes, ask what the finding means for you, given how often it didn’t progress in the ARIC cohort.
- If you have diabetes, ask whether your goal fits your age and health, especially if you have low blood sugar episodes.
A primary care clinician can interpret HbA1c alongside other tests. An endocrinologist or geriatrician can help set diabetes goals, particularly for older adults on several medications.
For the difference between a longer-term glucose average and two fasting snapshots, Fasting Insulin vs. Fasting Glucose explains what each test contributes.
Bottom Line
HbA1c reflects two to three months of average blood sugar and predicts diabetes, heart disease, stroke and death in adults without diabetes. In ARIC, death rates rose at both the high end and below 5.0%; researchers could not explain the low-end association. ACCORD found more deaths with an intensive medication strategy in people with type 2 diabetes and high cardiovascular risk. In the later ARIC study of adults in their 70s with HbA1c-defined prediabetes, returning to normal HbA1c or dying during follow-up was more common than developing diabetes. These findings concern different populations and do not establish that a low HbA1c itself causes harm. There’s no established HbA1c target for living longer, and diabetes groups still differ on goals for older adults. Discuss your result, and any treatment goal, with a clinician who knows your health.
A NOTE FROM LONGEVITY365
We read research, consult expert perspectives and work to make complicated health information easier to understand. What you’re reading here reflects how we’ve interpreted and organized that information. It is educational content—not personal medical advice, diagnosis or treatment guidance.
We’re not perfect, and neither is the available research. Evidence changes, new studies emerge and what’s appropriate for one person may not be appropriate for another.
Use this article as a starting point for your own research and conversations with qualified professionals. Always talk with your doctor or another trusted healthcare professional before making decisions that could affect your health, particularly if you take medications, are receiving treatment, have existing health conditions, are pregnant or have other circumstances that could affect what’s appropriate for you.
Reader Questions
A few questions to carry into the comments or your next conversation. Please leave out identifying or personal medical details.
- 01How has the difference between a risk marker and a treatment target changed the way you read an HbA1c result?
- 02What would you want to understand about a study population before applying its findings to someone else?
- 03Which part of the disagreement over older-adult diabetes goals would you want explained further?
Extra Insights & Sources
For readers who want the details behind each claim above.
What We Know
- Higher HbA1c predicts diabetes, heart disease, stroke and death in adults without diabetes. Supported (observational).
- Very low HbA1c (below 5.0%) was linked to higher mortality in the same cohort. Supported (observational).
- Intensive glucose lowering toward normal HbA1c increased deaths in high-risk type 2 diabetes in ACCORD. Supported (one large randomized trial); the ACP’s review of the major trials found tighter targets didn’t reduce deaths or heart events.
- Many older adults with prediabetes by HbA1c don’t go on to develop diabetes. Supported (observational).
What We Don’t Know
- Why very low HbA1c is linked to higher mortality. Unknown.
- Whether lowering HbA1c within the normal range, in people without diabetes, extends lifespan. Unknown. No trial has tested it.
- The best HbA1c for healthy aging in any individual. Unknown. No “optimal longevity” target is established.
- Exactly how loose diabetes goals should be for healthy older adults. Contested between the ACP and the ADA.
The ARIC study in detail
Selvin et al., New England Journal of Medicine, 2010. Researchers measured HbA1c in stored whole-blood samples from 11,092 Black or white adults who attended the second ARIC visit (1990–1992) and had no history of diabetes or cardiovascular disease. ARIC is a community-based study of middle-aged adults from four US communities. Median follow-up was about 14 years.
Compared with an HbA1c of 5.0% to under 5.5%, the adjusted risk rose with each step up:
| HbA1c | Diagnosed diabetes | Coronary heart disease | Death from any cause |
|---|---|---|---|
| Below 5.0% | 0.52 | 0.96 | 1.48 |
| 5.0% to <5.5% | 1.00 (reference) | 1.00 | 1.00 |
| 5.5% to <6.0% | 1.86 | 1.23 | 1.18 |
| 6.0% to <6.5% | 4.48 | 1.78 | 1.59 |
| 6.5% or higher | 16.47 | 1.95 | 1.65 |
Hazard ratios (HRs; model 2) adjusted for age, sex, race, cholesterol, triglycerides, body size, blood pressure, family history, education, alcohol, physical activity and smoking. A hazard ratio compares how quickly events occur among people still at risk at a given point during follow-up. A value of 1 means no difference between groups; above 1 means a higher hazard. For example, 1.48 means a 48% higher relative hazard, not a 48% chance of dying or a 48-percentage-point increase in that chance.
The hazard ratios for stroke were similar to those for coronary heart disease. Once HbA1c was in the model, fasting glucose no longer predicted cardiovascular disease or death. The authors concluded that, compared with fasting glucose, HbA1c was about as closely linked to diabetes risk and more closely linked to the risks of cardiovascular disease and death from any cause.
The J-curve. In post hoc analyses, the higher death rate below 5.0% persisted after excluding participants with anemia, adjusting for hematocrit and mean corpuscular volume, and excluding deaths in the first 3 years of follow-up. The authors wrote that the J-shaped relation warrants further study of the health risks of low-normal blood sugar, and of factors other than glucose that may affect glycated hemoglobin.
The ACCORD trial in detail
ACCORD Study Group (Gerstein HC et al.), New England Journal of Medicine, 2008. The trial randomly assigned 10,251 patients with type 2 diabetes (mean age 62.2; median starting HbA1c 8.1%; 38% women; 35% with a previous cardiovascular event) to intensive therapy targeting HbA1c below 6.0% or standard therapy targeting 7.0% to 7.9%. At 1 year, median HbA1c was 6.4% and 7.5% in the two groups.
Higher mortality led to the intensive arm being stopped in February 2008, 17 months early, after a mean of 3.5 years. Deaths: 257 intensive vs 203 standard (HR 1.22, 95% CI 1.01 to 1.46). The primary outcome (nonfatal heart attack, nonfatal stroke or cardiovascular death) occurred in 352 vs 371 patients (HR 0.90, 95% CI 0.78 to 1.04; P=0.16), not a significant difference. Hypoglycemia requiring medical assistance occurred at an annualized rate of 3.1% vs 1.0%, and mean weight gain at 3 years was 3.5 kg vs 0.4 kg. The authors concluded that intensive therapy raised mortality without significantly reducing major cardiovascular events.
Here, HR compares the intensive strategy with the standard strategy. The death HR of 1.22 means a 22% higher relative hazard during follow-up, not that 22% of participants died. CI means confidence interval: the 95% CI shows statistical uncertainty around the estimate under the study model. An interval spanning 1, as with the combined cardiovascular outcome, includes no difference between groups. P values describe how compatible the data are with a model assuming no group difference; smaller values indicate less compatibility. P=0.16 did not meet the study’s threshold for statistical significance. It does not give the probability that the treatment works.
Prediabetes in older adults in detail
Rooney MR et al., JAMA Internal Medicine, 2021 (senior author Elizabeth Selvin). The analysis included 3,412 ARIC participants without diabetes at the 2011–2013 visit (mean age 75.6; 60% women; 17% Black), with a median follow-up of 5.0 years (range up to 6.5). Of the 1,490 (44%) with HbA1c of 5.7% to 6.4%, 97 (9%) progressed to diabetes, 148 (13%) regressed to normal HbA1c and 207 (19%) died. Among those with impaired fasting glucose, 8% progressed, 44% regressed and 16% died. The authors concluded that “regression to normoglycemia or death was more frequent than progression to diabetes.”
ADA on prevention trials. The ADA’s 2026 diagnosis section states that the efficacy of interventions to prevent type 2 diabetes “has been demonstrated mainly among individuals with prediabetes who have impaired glucose tolerance (IGT) with or without elevated fasting glucose, not for individuals with isolated impaired fasting glucose (IFG) or for those with prediabetes defined by A1C criteria.” The same section describes HbA1c as a measure of glucose exposure “over the past ∼2–3 months,” and lists anemia, kidney failure, dialysis, cirrhosis and some hemoglobin variants among factors that can affect it.
Diabetes goals for older adults in detail
ACP 2018 (Qaseem A et al., Annals of Internal Medicine). Guidance statement 4 reads in full: “Clinicians should treat patients with type 2 diabetes to minimize symptoms related to hyperglycemia and avoid targeting an HbA1c level in patients with a life expectancy less than 10 years due to advanced age (80 years or older), residence in a nursing home, or chronic conditions (such as dementia, cancer, end-stage kidney disease, or severe chronic obstructive pulmonary disease or congestive heart failure) because the harms outweigh the benefits in this population.” Explaining its 7% to 8% range, the ACP wrote that the major trials “showed that treating to targets of 7% or less compared with targets around 8% did not reduce death or macrovascular events over about 5 to 10 years of treatment but did result in substantial harms, including but not limited to hypoglycemia.”
ADA 2026 Standards of Care, Section 13 (Older Adults), Table 13.2 treatment-goal framework.
| Health status (ADA) | Reasonable HbA1c goal |
|---|---|
| Healthy: few coexisting chronic illnesses, intact cognitive and functional status | Below 7.0%–7.5% |
| Complex/intermediate: multiple chronic illnesses, difficulty with two or more instrumental activities of daily living, or mild to moderate cognitive impairment | Below 8.0% |
| Very complex/poor health: post-acute or long-term care, end-stage chronic illness, moderate to severe cognitive impairment, or difficulty with two or more basic activities of daily living | Avoid reliance on HbA1c; base decisions on avoiding low blood sugar and symptomatic high blood sugar |
Instrumental activities are tasks involved in independent living, such as shopping, managing money or taking medicines. Basic activities concern personal care, such as bathing, dressing or eating. These are different kinds of limitation, not interchangeable labels.
Table 13.2 is a consensus framework rather than a rule for readers to classify themselves: the ADA notes that not everyone fits one category. Goals account for health, function, treatment risks, and the person’s and care partner’s preferences and resources; those circumstances can change. A lower goal may be considered if achievable without recurrent or severe low blood sugar or undue treatment burden.
The ADA adds that “Older adults with very complex or poor health receive minimal benefit from stringent glycemic goals.”
Sources
- Selvin E, et al. Glycated hemoglobin, diabetes, and cardiovascular risk in nondiabetic adults, New England Journal of Medicine, 2010: PubMed 20200384
- ACCORD Study Group (Gerstein HC, et al.). Effects of intensive glucose lowering in type 2 diabetes, New England Journal of Medicine, 2008: PubMed 18539917
- Rooney MR, et al. Risk of progression to diabetes among older adults with prediabetes, JAMA Internal Medicine, 2021: PubMed 33555311
- Qaseem A, et al. Hemoglobin A1c targets for glycemic control with pharmacologic therapy (American College of Physicians guidance statement), Annals of Internal Medicine, 2018: PubMed 29507945
- American Diabetes Association Professional Practice Committee. 13. Older Adults: Standards of Care in Diabetes—2026, Diabetes Care, 2026: PubMed 41358888
- American Diabetes Association Professional Practice Committee. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026, Diabetes Care, 2026: PubMed 41358893
Notes
Note 1: Funded by the National Institutes of Health, through National Institute of Diabetes and Digestive and Kidney Diseases grants and National Heart, Lung, and Blood Institute contracts. The authors’ individual financial disclosures were published with the article at NEJM.org and aren’t reproduced in the public PubMed Central copy.
Note 2: Funded by the National Heart, Lung, and Blood Institute, other parts of the National Institutes of Health and the Centers for Disease Control and Prevention. Thirteen companies, including Abbott, AstraZeneca, GlaxoSmithKline, Merck, Novartis, Novo Nordisk and Sanofi-Aventis, provided study medications, equipment or supplies, and several investigators reported consulting fees, lecture fees or grants from diabetes-drug makers.
Note 3: Funded by National Institutes of Health grants (National Heart, Lung, and Blood Institute and National Institute of Diabetes and Digestive and Kidney Diseases). Authors reported grants from the NIH, the Foundation for the NIH and the Johns Hopkins Bloomberg School of Public Health, and no other disclosures.
Note 4: Funded exclusively from the American College of Physicians’ operating budget. One author reported grants and fees from Healthwise, a nonprofit, outside the submitted work; two committee members were recused from voting because of active direct or indirect financial conflicts.
Note 5: Written by the American Diabetes Association’s Professional Practice Committee and endorsed by the American Geriatrics Society. The section doesn’t state its own funding; each contributor’s duality-of-interest information is published separately by Diabetes Care.
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