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Why You Should Be Testing your HbA1c

Nourish Balance Thrive

Elevated blood glucose is one of the earliest and most common indicators of worsening metabolic health, insulin resistance and cardiovascular disease. For our clients, fasting blood glucose and triglycerides are amongst the first things we test to get a snapshot view of metabolic health. We’ve now added HbA1C - a marker that offers a broader look at glycemic history - to our baseline blood panel, to better evaluate our clients.

On this podcast, NBT Scientific Director Megan Hall talks about the HbA1C blood test: what it is, who needs it, and why you should care. Megan talks about the optimal reference range for this test, and when to become concerned about your result (hint: it’s sooner than your doctor would have you believe). She also talks about exactly what to do if your A1C is out of range, and how a continuous glucose monitor can help you evaluate your body’s response to different foods and other environmental factors.

Here’s the outline of this interview with Megan Hall:

[00:00:48] HbA1C (aka glycated haemoglobin): a marker of your glycemic history.

[00:02:27] Glucose to A1C conversion chart.

[00:02:52] Megan's outline for this podcast.

[00:03:04] Why you should care about HbA1C.

[00:03:48] Optimal ranges for HbA1C: 5.0% to 5.4%.

[00:04:33] Studies supporting optimal reference range: 1. Zhong, Guo-Chao, et al. "HbA 1c and Risks of All-Cause and Cause-Specific Death in Subjects without Known Diabetes: A Dose-Response Meta-Analysis of Prospective Cohort Studies." Scientific reports 6.1 (2016): 1-11; 2. Schöttker, Ben, et al. "HbA 1c levels in non-diabetic older adults–No J-shaped associations with primary cardiovascular events, cardiovascular and all-cause mortality after adjustment for confounders in a meta-analysis of individual participant data from six cohort studies." BMC medicine 14.1 (2016): 1-17; 3. Li, Fu-Rong, et al. "Glycated hemoglobin and all-cause and cause-specific mortality among adults with and without diabetes." The Journal of Clinical Endocrinology & Metabolism 104.8 (2019): 3345-3354; 4. Pai, Jennifer K., et al. "Hemoglobin a1c is associated with increased risk of incident coronary heart disease among apparently healthy, nondiabetic men and women." Journal of the American Heart Association 2.2 (2013): e000077.

[00:06:12] Prediabetes range: 5.7% to 6.4% (above 6.4% is diabetes).

[00:07:06] Only 12% of the population is metabolically healthy; Study: Araújo, Joana, Jianwen Cai, and June Stevens. "Prevalence of Optimal Metabolic Health in American Adults: National Health and Nutrition Examination Survey 2009–2016." Metabolic syndrome and related disorders 17.1 (2019): 46-52.

[00:07:31] Limitations and caveats of the A1C blood marker.

[00:08:05] Partial marker of mean glycemic exposure; Article: Bloomgarden, Zachary. "Beyond HbA1c." Journal of diabetes 9.12 (2017): 1052-1053.

[00:08:53] Things that cause HbA1C to be falsely low or high.

[00:10:14] Study: Virtue, Mark A., et al. "Relationship between GHb concentration and erythrocyte survival determined from breath carbon monoxide concentration." Diabetes Care 27.4 (2004): 931-935.

[00:12:36] Racial and ethnic differences: Herman, William H., and Robert M. Cohen. "Racial and ethnic differences in the relationship between HbA1c and blood glucose: implications for the diagnosis of diabetes." The Journal of Clinical Endocrinology & Metabolism 97.4 (2012): 1067-1072.

[00:12:42] Other markers of glycemic regulation.

[00:12:55] Drawbacks of Glycomark.

[00:14:08] Reticulocytes - helpful to calculate RBC lifespan.

[00:14:40] Equation: RBC survival (days) = ~ 100 / [Retics (%) / RLS (days)]

[00:15:44] Sign up for our group program to get a blood test + report + 4 group coaching sessions + help videos.

[00:16:44] Continuous Glucose Monitor (CGM).

[00:17:26] Podcast: Continuous Glucose Monitoring to Prevent Disease and Increase Healthspan, with Kara Collier, RDN.

[00:17:46] Get $50 off your Nutrisense membership when you support NBT on Patreon.

[00:18:26] Studies demonstrating that HbA1C is not the perfect marker: 1. Cohen, Robert M., et al. "Red cell life span heterogeneity in hematologically normal people is sufficient to alter HbA1c." Blood, The Journal of the American Society of Hematology 112.10 (2008): 4284-4291; 2. Wright, Lorena Alarcon-Casas, and Irl B. Hirsch. "The challenge of the use of glycemic biomarkers in diabetes: reflecting on hemoglobin A1C, 1, 5-Anhydroglucitol, and the glycated proteins fructosamine and glycated albumin." Diabetes spectrum 25.3 (2012): 141-148; 3. Dubowitz, N., et al. "Aging is associated with increased HbA1c levels, independently of glucose levels and insulin resistance, and also with decreased HbA1c diagnostic specificity." Diabetic Medicine 31.8 (2014): 927-935.

[00:18:58] What to do if your A1C is out of range: Diet, lifestyle, measure other markers, monitor blood glucose.

[00:19:35] Cellular vs. acellular carbs.

[00:22:25] Simon Marshall, PhD. on stress management: How to Manage Stress.

[00:24:19] 4-quadrant model.

[00:26:07] Retest after 2-3 months.

[00:27:58] Join our group program.

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