# A1C test and blood letting. **URL:** \ **Category:** In My Humble Opinion\ **Created:** [March 26, 2018, 5:14pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213 "2018-03-26T17:14:02Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Lou\_O](https://avatars.discourse-cdn.com/v4/letter/l/ed8c4c/32.png) [@Lou\_O](https://boards.straightdope.com/u/Lou_O)\ **Post date:** [March 26, 2018, 5:14pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/1 "2018-03-26T17:14:02Z")
So I do some online study of A1C. It’s a relatively new test to determine your long term glucose; how much sugar is bound to the red blood cells for ~ 3 - 4 months. My research also finds that loss of blood will show lower A1C…think of women who are still having their periods. Or, (assumption here) perhaps people who donate blood on a regular basis will have low A1C%. I usually donate blood 4 times a year. (I’m actually a 40 + gallon donor over 45 years.) Therefore does a person eliminate excess blood sugar when getting rid of (donating) blood? And, perhaps, is getting rid of (donating) blood a good thing to do to control your blood sugar rather than taking big Pharma big dollar drugs? You may or may not get a straight answer from your doctor because they are in the biz of pushing lots of expensive drugs. Your thoughts? I almost get the feeling that the ‘A1C Test’ was developed so big Pharma could push some drugs that they developed. Of course doctors get cash or perks to prescribe these drugs, which is a well known issue in the industry. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 26, 2018, 5:32pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/2 "2018-03-26T17:32:18Z")
You replenish blood sugar on a lot faster timescale than you do red cells. Donate blood often enough to make a major dent on your blood sugar, and you’ll be dead of anemia. ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [March 26, 2018, 5:32pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/3 "2018-03-26T17:32:28Z")
I’m a woman who is a regular blood donor and who has periods and my A1C is still frustratingly high (7.2 last time). I take the expensive drugs. Even if it’s true that losing blood lowers one’s A1C, mine is still too high so I still need the drugs. Diet and exercise can lower one’s A1C and I can assure you that doctors still recommend that. I don’t know why they would “hide” some other non-pharmaceutical recommendation… ---
**Author:** ![Surreal](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@Surreal](https://boards.straightdope.com/u/Surreal)\ **Post date:** [March 26, 2018, 8:47pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/4 "2018-03-26T20:47:20Z")
1. Donating blood prior to an HbA1c test will reduce the average age of your red blood cells, which in turn will reduce the degree of glycosylation and produce an artificially low A1c reading. 2. Donating blood also reduces serum ferritin, which can improve insulin sensitivity and could reduce your A1c result (not artificially). ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [March 26, 2018, 8:59pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/5 "2018-03-26T20:59:09Z")
> [@Lou\_O](#): > > You may or may not get a straight answer from your doctor because they are in the biz of pushing lots of expensive drugs. Your thoughts? I almost get the feeling that the ‘A1C Test’ was developed so big Pharma could push some drugs that they developed. Of course doctors get cash or perks to prescribe these drugs, which is a well known issue in the industry. Are you saying you would find answers from those in the medical profession to be suspect? That may be a problem if you want an accurate answer. ---
**Author:** ![dwyr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dwyr/32/363_2.png) [@dwyr](https://boards.straightdope.com/u/dwyr)\ **Post date:** [March 26, 2018, 9:23pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/6 "2018-03-26T21:23:06Z")
Speaking as a medical technologist who has been running glycos, i.e. A1c tests, for many years, you would have to lose a lot more blood than a donor unit for it to affect your results significantly. ---
**Author:** ![Iggy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iggy/32/3364_2.png) [@Iggy](https://boards.straightdope.com/u/Iggy)\ **Post date:** [March 26, 2018, 11:10pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/7 "2018-03-26T23:10:16Z")
\ Yeah, my doctor is gonna get rich from my Metformin prescription. With the kickback she must get on my prescription which costs $4 per month. She will only need a couple thousand more patients to be able to make that boat payment. \ HbA1c was characterized in 1968. It is not a new test. ---
**Author:** ![Mean\_Mr.Mustard](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mean_mr.mustard/32/3865_2.png) [@Mean\_Mr.Mustard](https://boards.straightdope.com/u/Mean_Mr.Mustard)\ **Post date:** [March 27, 2018, 12:45am UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/8 "2018-03-27T00:45:00Z")
Great idea, dismissing doctors input in favor of random internet peoples’. mmm ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [March 27, 2018, 4:04am UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/9 "2018-03-27T04:04:10Z")
Why put gas in the tank when I can just get better mileage by turning off the air conditioning? ---
**Author:** ![USCDiver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/uscdiver/32/354_2.png) [@USCDiver](https://boards.straightdope.com/u/USCDiver)\ **Post date:** [March 27, 2018, 5:05am UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/10 "2018-03-27T05:05:40Z")
I’m going to ignore the Big Pharma nonsense. But even if blood donation artificially lowered your A1c, why wouldn’t you want to get an accurate reading? The A1c itself is just an estimate, getting a lower result than you actually have will only serve to have your blood glucose improperly managed. ---
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [March 28, 2018, 2:44am UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/11 "2018-03-28T02:44:25Z")
I have another related question to A!c. Suppose your pancreatic function was normal but your daily intake of sweets and sugars was just too high. Would this give a high reading for A1c? Would doctors likely prescribe drugs here not knowing your diet when possibly diet alone was all that is needed? ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [March 28, 2018, 2:53pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/12 "2018-03-28T14:53:26Z")
Since the OP is asking for opinions, let’s move this to IMHO. Colibri General Questions Moderator ---
**Author:** ![romadea](https://avatars.discourse-cdn.com/v4/letter/r/b4bc9f/32.png) [@romadea](https://boards.straightdope.com/u/romadea)\ **Post date:** [April 15, 2018, 8:50pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/13 "2018-04-15T20:50:16Z")
> [@HoneyBadgerDC](#): > > I have another related question to A!c. Suppose your pancreatic function was normal but your daily intake of sweets and sugars was just too high. Would this give a high reading for A1c? Would doctors likely prescribe drugs here not knowing your diet when possibly diet alone was all that is needed? 1. No, it shouldn’t. If your pancreas is working correctly, insulin should redistribute the sugar quickly enough to the interior of your body’s cells (particularly the liver cells) so that sugar isn’t hanging out in the bloodstream for hours and hours, latching on to RBCs and causing the high A1C. 2. I’m graduating from medical school in a few months, so I can tell you that what we’re taught to do is counsel patients to change their lifestyle (diet, exercise, smoking cessation) first before prescribing any drugs. However, having worked in clinics and hospitals for a couple years now, I can also tell you that some doctors will prescribe drugs as well as lifestyle modifications right off the bat. It’s a judgment call. For example, if a patient is hospitalized for diabetes-related complications before they even know they have diabetes, they’re likely too far gone to start out by eating fewer carbs. They’ll be started on meds while they work on changing their habits. If the changes they make are successful, they stand a chance of being weaned off meds. ---
**Author:** ![romadea](https://avatars.discourse-cdn.com/v4/letter/r/b4bc9f/32.png) [@romadea](https://boards.straightdope.com/u/romadea)\ **Post date:** [April 15, 2018, 9:02pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/14 "2018-04-15T21:02:28Z")
> [@Chronos](#): > > You replenish blood sugar on a lot faster timescale than you do red cells. Donate blood often enough to make a major dent on your blood sugar, and you’ll be dead of anemia. Exactly. Blood sugar changes minute to minute, while blood cells usually live for at least 3 months - which is why the HbA1C test works to tell you your average blood sugar over the previous 3 months. The sugar attached to the RBCs isn’t the cause of the problem, it’s a side effect of the problem. ---
**Author:** ![romadea](https://avatars.discourse-cdn.com/v4/letter/r/b4bc9f/32.png) [@romadea](https://boards.straightdope.com/u/romadea)\ **Post date:** [April 17, 2018, 2:17am UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/15 "2018-04-17T02:17:34Z")
> [@romadea](#): > > 1. No, it shouldn’t. If your pancreas is working correctly, insulin should redistribute the sugar quickly enough to the interior of your body’s cells (particularly the liver cells) so that sugar isn’t hanging out in the bloodstream for hours and hours, latching on to RBCs and causing the high A1C. > > 2. I’m graduating from medical school in a few months, so I can tell you that what we’re taught to do is counsel patients to change their lifestyle (diet, exercise, smoking cessation) first before prescribing any drugs. However, having worked in clinics and hospitals for a couple years now, I can also tell you that some doctors will prescribe drugs as well as lifestyle modifications right off the bat. It’s a judgment call. For example, if a patient is hospitalized for diabetes-related complications before they even know they have diabetes, they’re likely too far gone to start out by eating fewer carbs. They’ll be started on meds while they work on changing their habits. If the changes they make are successful, they stand a chance of being weaned off meds. Just wanted to add I looked this up today and there are a variety of guidelines that exist about when to start Metformin + lifestyle changes vs. lifestyle changes alone. The most aggressive one that I found (Canadian guidelines) says HbA1C \> 7% should start with both. (HbA1C of 6.5% or higher universally gets you a diabetes diagnosis). The guidelines from the American Diabetes Association suggest that it’s up to the patient and physician to decide when it’s best to start drugs. ---
**Author:** ![susan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/susan/32/17537_2.png) [@susan](https://boards.straightdope.com/u/susan)\ **Post date:** [April 17, 2018, 2:11pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/16 "2018-04-17T14:11:23Z")
> [@](#): > > It’s a relatively new test A1c isn’t a new test. ---
**Author:** ![psychobunny](https://avatars.discourse-cdn.com/v4/letter/p/54ee81/32.png) [@psychobunny](https://boards.straightdope.com/u/psychobunny)\ **Post date:** [April 17, 2018, 5:15pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/17 "2018-04-17T17:15:45Z")
With regard to metformin, I just want to clarify that there are good studies showing that using it in people who do not yet meet the criteria for diabetes can reliably delay the onset of diabetes as well as evidence for a decrease in cardiac events from use in these patients so that early use may be beneficial. ---
**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\ **Post date:** [April 17, 2018, 5:20pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/18 "2018-04-17T17:20:49Z")
Whatever effect that donating blood will have on your A1C and blood sugar is utterly miniscule. ---
**Author:** ![psychobunny](https://avatars.discourse-cdn.com/v4/letter/p/54ee81/32.png) [@psychobunny](https://boards.straightdope.com/u/psychobunny)\ **Post date:** [April 17, 2018, 5:20pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/19 "2018-04-17T17:20:53Z")
Just wanted to add a [link](https://www.niddk.nih.gov/about-niddk/research-areas/diabetes/diabetes-prevention-program-dpp). ---
**Author:** ![Jasmine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jasmine/32/2964_2.png) [@Jasmine](https://boards.straightdope.com/u/Jasmine)\ **Post date:** [April 17, 2018, 5:33pm UTC](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213/20 "2018-04-17T17:33:04Z")
I researched the A1C test as well and found out something that definitely could affect me in terms of how accurate the test may be. Apparently, the test is calibrated for “standard” hemoglobin. As a full blooded southern Italian, however, I have a hemoglobin variant which affects the validity of the test. My doctor has told me that I am testing too high, and he wants to get me on those drugs, some of which have awful and, as far as I am concerned, dangerous side effects such as a big weight gain. I told him no and explained why. Besides, at 5’9" and only 120 lbs, and with an extremely low sugar intake, and with none of the symptoms that typically come with Type II diabetes, I really don’t feel I need any. I feel fine. [Next page](https://boards.straightdope.com/t/a1c-test-and-blood-letting/811213.md?page=2)