Biomarkers · Glycemic & Metabolic
Glycated Hemoglobin (HbA1c)
U-shaped: both low and high values carry risk. In NHANES 1999–2018 with linked mortality to 2019, each standard deviation is associated with a hazard ratio of 1.18. U-shaped: slope not comparable
Hazard ratios relative to each curve's own reference value, so the two curves need not cross 1 at the same point. The dotted vertical line marks the NHANES median.
Where people sit
Population percentiles (%) by sex and age band. Cycle or source as recorded in the catalogue.
| Sex | Age | 5th | 25th | Median | 75th | 95th | n | Cycle / source |
|---|---|---|---|---|---|---|---|---|
| All | 20-39 | 4.80 | 5.10 | 5.30 | 5.50 | 6.20 | 2,710 | 2017-2018 |
| All | 40-59 | 4.90 | 5.30 | 5.50 | 5.90 | 8.10 | 2,670 | 2017-2018 |
| All | 60+ | 5.10 | 5.40 | 5.70 | 6.20 | 8.70 | 2,820 | 2017-2018 |
| All | all | 4.90 | 5.20 | 5.50 | 5.80 | 7.80 | 8,200 | 2017-2018 |
| Men | all | 4.90 | 5.30 | 5.50 | 5.90 | 7.90 | 3,980 | 2017-2018 |
| Women | all | 4.90 | 5.20 | 5.40 | 5.80 | 7.60 | 4,220 | 2017-2018 |
What studies found when this marker was changed
Effects on the biomarker reported in the cited studies. They describe what happened in those populations, not a recommendation for anyone. See all catalogued interventions.
| Type | Intervention | Reported effect | Evidence | Source |
|---|---|---|---|---|
| clinical | Progressive beta-cell failure and unmanaged insulin resistance | +1.5% to +4.5% absolute elevation (HbA1c > 8.0%) | clinical guideline | American Diabetes Association. Diabetes Care. 2023;46:S19-S40. |
| diet | Low-carbohydrate / Ketogenic dietary intervention | -0.8% to -1.5% absolute HbA1c reduction | meta-analysis | Goldenberg JZ, et al. BMJ. 2021;372:m4743. |
| diet | Chronic high-glycemic ultra-processed dietary pattern | +0.5% to +1.2% elevation | prospective cohort | Srour B, et al. JAMA Intern Med. 2020;180:283-291. |
| exercise | Combined aerobic and resistance training (3x/week) | -0.5% to -0.9% absolute HbA1c reduction | meta-analysis | Church TS, et al. JAMA. 2010;304:2253-2262. |
| lifestyle | Intensive lifestyle intervention (Diabetes Prevention Program) | -0.6% to -1.2% absolute reduction; 58% diabetes risk reduction | rct | Knowler WC, et al. N Engl J Med. 2002;346:393-403. |
| pharmacologic | GLP-1 Receptor Agonists (Semaglutide/Tirzepatide) or Metformin | Lowers HbA1c by 1.0-2.4% and induces significant weight loss | RCT | Estruch R, et al. Primary Prevention of Cardiovascular Disease with a Mediterran… |
| pharmacologic | Dual GIP/GLP-1 receptor agonist (Tirzepatide 5-15mg) | -1.8% to -2.6% absolute HbA1c reduction | rct | Frias JP, et al. N Engl J Med. 2021;385:503-515. |
Sources
- Hazard curve: Recalculated from mortality_association (HR=1.52 quartile_extreme); per-SD log(HR)=0.3267.
- Currie CJ, et al. Survival as a function of HbA1c in people with type 2 diabetes: a retrospective cohort study. Lancet. 2010;375(9713):481-489.
- Empirical curve: our Cox model with age and sex, NHANES 1999–2018 with linked mortality to 2019.
Map Glycated Hemoglobin (HbA1c) against another biomarker · Featured: HbA1c × body mass index.