# HbA1c: do the latest BG samples count for more? **URL:** \ **Category:** Treatment\ **Tags:** a1c\ **Created:** [October 16, 2018, 11:08pm UTC](https://forum.fudiabetes.org/t/hba1c-do-the-latest-bg-samples-count-for-more/5237 "2018-10-16T23:08:23Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![Michel](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/michel/32/387_2.png) [@Michel](https://forum.fudiabetes.org/u/Michel)\ **Post date:** [October 15, 2018, 4:10pm UTC](https://forum.fudiabetes.org/t/hba1c-do-the-latest-bg-samples-count-for-more/5237/2 "2018-10-15T16:10:48Z")
> [@Meta Study: Long-term Glycemic Variability and Risk of Adverse Outcomes](https://forum.fudiabetes.org/t/meta-study-long-term-glycemic-variability-and-risk-of-adverse-outcomes/5121/51): > > As for recent weeks having more impact, I think it is the opposite, according to a paper that came out a couple months ago. The first 30 days of your last 120-day period should account for about 50% of your result. And the last 30 days of the 120 should only account for about 5% of the result. I would be surprised to find a study stating this conclusion: - the HbA1c measures glycated hemoglobin, which is found in red blood cells. - red blood cells die out over an 8-12 week cycle, using a probability curve for the die-out (likely Gaussian, although I don’t have proof on that) - a sample of red blood cells for the A1c will therefore count more newer cells than older cells - therefore, more recent times in the 90-day window will be overemphasized when measuring an A1c (or anything based on red blood cells). - This is also the understanding presented by every endocrinologist I have ever talked to. I would need to read a very well researched and documented study if it were to present such a counterintuitive result before believing it 🙂 I am not even sure that one study would be enough. --- _[View the full topic](https://forum.fudiabetes.org/t/hba1c-do-the-latest-bg-samples-count-for-more/5237)._