Borderline A1C levels (pre-diabetes)

Anyone here dealing with having elevated A1C levels in the range? I have had levels of 5.6-6.0% over the past 5 years, which as part of my annual physical flags me as someone needing to investigate more. Their typical advice – lose weight, exercise more, eat better, doesn’t really apply to most of us, given our levels of fitness. I AM investigating the eat better lever. I generally eat very healthily, but want to look into dialing in macro balance, timing, portions, better. And while I don’t eat fast food, sugary snacks/drinks off the bike, I of course eat lots of sugar on the bike and wonder if something I am doing is inadvertently impacting my body’s ability to regulate blood sugar.

My physical this year had some other borderline results that may/may not be related (slightly elevated potassium, low specific gravity), so I am digging in a little more.

I have read some articles/studies about endurance athletes and predisposition for diabetes, but not sure I am any wiser. Maybe a podcast topic?

I’m betting that we’re going to see an increase in a cohort of people who participate in endurance sports succumbing to type 2 diabetes and pre diabetes.

The doctor’s advice of losing weight and eating better will still apply and that may be where an endurance athlete is lulled into a sense of security. By the metrics of the general population, it would appear that an endurance athlete is not that overweight/obese and gets plenty of exercise. The constants that you can’t control, however, is time (old age) and genetics. Overweight and obesity are risk factors, but uncontrolled blood sugars is multifactorial and specific to the individual. A primary care physician may only be versed in dealing with the general risk factors but specific and specialized care may take a more well versed professional.

The biggest thing you can do is to measure and probably decrease your carb consumption. How deep down the rabbit hole of measuring do you want to go? The first part is to measure yourself. If diabetes runs in the family and/or you’ve done some genetic risk factor testing, that’d be a start. One of the best baseline tests of your ability to handle carbs is the Glucose Tolerance Test (GTT). If you go more advanced, and with the help of a physician in the know, you can couple that GTT test with an insulin test. From this, you’ll get a good idea of how you respond to a glucose challenge. The goal with this combo test is to see if you’re in this weird area where you may have glucose control but am seeing some insulin resistance.

The next step is that you can start measuring your post meal blood glucose. Your fasting blood glucose probably won’t tell you much but knowing the trend of your glucose levels after a meal can be pretty eye opening. Maybe some favorite meals in which you thought was healthy is devastating from the perspective of insulin resistance. Finger stick based testing is very cheap nowadays but we’re interested in your post meal trends so some sort of continuous glucose monitoring is most desirable. That’s more expensive and in some countries a prescription is required. From there you can address diet and behavioral changes while getting some immediate feedback through the glucose testing.

Other risk factors with regard to diet include saturated fat consumption. Higher saturated fat consumption increases the chances of insulin resistance. Timing of carb consumption is important. Are you loading carbs throughout the day? Only carb up for your activity and also an appropriate amount. What are your goals for cycling? Health? or Podium finishes? Maybe you don’t need much carbs at all if being a peak performer isn’t your objective.

Do you fast? Evidence shows that fasting every once can have beneficial effects that last. Another behavioral change that should be considered.

I would say the biggest controllable risk factor for endurance athletes and the predisposition for diabetes is behavioral. It’s not knowing how they are being impacted by their diet and not adapting to their aging body.


Wow. I can’t thank you enough for your detailed response. You have provided essentially a great roadmap for me to think about. I already made an appointment

I’ve tracked food before and talked to a general nutritionist who was checking for my macros and quality/quantity of food, but didn’t dive into timing or testing. Seems like a logical next step. This year I DID increase my carb intake to fuel indoor rides in the early AM, or the night before big weekend rides.

I am 45, 5’ 11" 70kg and have generally have felt fit. Pre-diabetes is part of a larger health concern that is building as I get older and ailments accumulate (Reynaud’s, Orthostatic Hypotension, Low BP/Blood Volume, Periodic viral brain infection, recent enlarged heart diagnosis) that all impact my quality of life, let alone quality of training. I have found that exercise, and cycling specifically, has been a critical component to balancing my health.

Thank you again. Very much appreciated.

Get a fasting insulin level test. Blood sugar levels don’t give any real clue as to your level of insulin resistance. I think there was a Flo podcast recently talking about this subject with respect to endurance athletes.

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SoundCloud - Hear the world’s sounds is the mentioned podcast.

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No problem!

You’re still young and your BMI is so low! Considering diabetes only brings on complications of the circulatory system it’s a good thing you’re trying to head it off before it becomes a bigger problem. Have you considered going low carb? If you’re just cycling for fitness, it seems like the pros would outweigh the cons.

I have tried low carb in the past. When I was 40 and 82kg I started with that for about 2 years. Then I started going to the gym, then started cycling. It was when cycling became the major portion of my fitness routine (2016) that carbs starting coming back into my diet. 2014 was my first A1C test (Dr. started including it in blood panel) and it was 5.7%. Dr. wasn’t too concerned, but said to monitor. At that time I was going to the gym regularly (no cycling), at a healthy weight, and probably was low-ish carbs.

Most doctors are great at healthcare, however, IMO healthcare has a different meaning. It should really be called sickcare. Their training leans towards the focus on identifying, and treating diseases without nearly as much of a focus on prevention.

Not to scare you or anything but if you’re in the 5.6-6.0% range I would really work on doing what you can. That statistic puts you at a higher risk category for type 2 diabetes. I know a lot of the trainerroad podcasts advocate carbs for high intensity, but if you’re not in it to win it, focus on your health.

An ounce of prevention is worth a pound of cure and I think you have a great opportunity here to get a lot done. Type 1 diabetics have an extremely hard time keeping their A1Cs below 6 and I’ve known a family with type 1 teenager be able to get his down to a 5.0 which is a huge accomplishment. If you’re ever looking for ideas on diet, a good type 1 diabetics group will probably have the best info you can find as they have to know.

What you described is exactly what I have, A1C of 5.7 to 6.2 for the last 10 years. Lost a bunch of weight and exercise, didn’t help. It went down to 5.4 once after donating blood.
However, more concerning, what got my attention is your enlarged heart diagnosis. I had that diagnosis back in 1992, which led to heart surgery for birth defect I had for 30 some years, SVASD. Along with your Reynaud’s, Orthostatic Hypotension, Low BP/Blood Volume you might want to have that investigated further.

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This gives me a little bit of pause as it’s not “of course”. I ride 8-12 hours per week and hardly ever resort to sugar. I usually take a banana with me, a rice cake bar sometimes, and only some extra sugar when I know it’s going to be a long/intense 4+ hour ride. I’ve only resorted to gels in fondos/events.

Anyway, it’s something to think about. Most rides don’t need to be “fueled” other than with healthy food.

There are conditions where a HgA1c test might not be accurate. I have a genetic anemia (thalassemia minor) that presents no problems for daily life and requires zero treatment but if I take a HgA1c test it will show as borderline or high. There are a bunch of things that can cause this borderline result so I’d research that and rule them all out before you decide you are borderline.


Thanks very much!

To give an update, I ended up monitoring my blood sugar for two months and it never went out of range, which satisfied my doctors. I also deep a deep investigation of my heart - they debunked the enlarged heart, did 2 MRIs with contrast, and other tests and my ticker is fine, which was a relief (understatement!).


You make a great point, and I have started experimenting with adding much more “real” food on the bike. I have found though that I do require a fair bit more of energy on the bike that I have been consuming in the past to avoid fatigue. So trying to get that in line. Thanks!

If you are interested you can google “James Morton” and “carbohydrate periodization”. He is the exercise physiologist that works with Ineos and a lot of other pro teams.

The gist is that you can train your body over time towards better fat utilization. If you give your body sugar for every workout you train it towards glycolysis.

Actually, I just just reading this Alan Couzens article on the same subject:

Apologies for reviving this topic - I have only just joined the forum. HbA1c is something I’ve been dealing with for the last 18 months.

A quick internet search will reveal HbA1c is discussed regularly on running and cycling forums. The recurring theme is athletes who have high or pre-diabetic long-term blood sugar levels, but ‘normal’ fasting blood sugar. This was my experience too.

My internet searches found there has not been much medical research into athletes’ long-term blood sugar levels. However I discovered a couple of interesting research papers (sorry no references). The upshot: there is some evidence endurance athletes can have higher HbA1c results than non-athletes; and that athletes who incorporate strength training (e.g. interval work which favours carb metabolisation) can have higher HbA1c than endurance athletes.

One simple explanation for this is that energy demands during exercise - particularly intensive exercise - put glycogen into the blood stream which otherwise would not be there.

Pre-diabetes has become an issue because of the increase in cases of type-2 diabetes. As part of my “treatment” I attended a pre-diabetes workshop. I was the only 65kg, vegetarian, life-long cyclist there. I didn’t really fit the demographic for the rest of the group, and on raising this with one of the Doctors present his response was, “Yes, and think how bad your blood sugar would be if you hadn’t looked after your self”!

My observation from this is some doctors do not understand the statistical modelling behind pre-diabetes diagnosis. It’s a model based on an overweight and inactive demographic. If a person fits the demographic and has a high HbA1c then he/she may be at risk of developing type-2 diabetes.

However, the model may not say much about people outside that demographic. In fact what it might indicate (given normal fasting blood sugar levels) is that athletes have a heightened sensitivity to insulin.

Something I learned which I have taken on board is about diet. The last 50 years have seen the demonisation of fats, whereas contemporary thinking is that carbs are the real danger. I have tried to ‘re-wire’ my relationship with dietary fats (not easy after a life-time of fat avoidance). I eat less bread and potatoes now and make up the deficit with more dairy and nuts. But I have to be careful about weight loss now - my body weight is much more sensitive to the exercise/ food balance.

The advice I would have liked 18 months ago following the pre-diabetic HbA1c assessment is: “Ask straight away for a fasting blood sugar test, and if that is okay avoid going back to the Doctor.”

My brother - who is a nurse and a cyclist (with a lower bmi than mine) advised me, if I was really worried, go and see a sports dietician.

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Have you eaten a lot of simple carbs which could explain the higher A1C? I’ve had friends who were vegetarian but the staples of their diet were bread, sugar, potatoes, and white rice.

There could be other factors that contribute to a slightly elevated A1C. I recently found out that this was the case for me as I have thalassemia which is a blood trait of people coming from the southern mediterranean area. So there could be some other factor in interpreting your results.

If the diet is in check, then maybe just watch the level?

I am the original poster and did just that. I wanted a belt and suspenders view and as I mentioned above, all came out fine after tracking my blood sugar for 2 months. I also went to more homemade food on the bike. But largely have stopped worrying about it for now. :mountain_biking_man:

I’m going to toss out something that worked for me but I’m not going to spend time in this thread defending it so if it doesn’t seem like it will work for you, I get it.

About 5 years ago my company starting health screening as a part of each participant’s health insurance cost. You didn’t have to get screened and screening would not hurt you by increasing your premium but it could help by decreasing your premium. Being a fairly fit guy for most of my lift I took the challenge and I scored 4/5. That was stunning but the reason for not scoring 5/5 was my A1C level. So I did the normal thing most people do which was not go to the doctor but instead I googled how to fix it :wink: I spent 14 months pretty much living by the diet outlined in that book.

My A1C went from 5.8 to 4.2-4.4 ever since. I don’t eat paleo anymore. My assumption is that the combination of regaining some insulin resistance and being very fit was enough for me to adopt the Nate diet (carbs and more carbs) and really not have my levels impacted by doing so.

So that’s what worked for me. N=1, your mileage may vary and all that stuff.

Good luck!


I’m certainly no expert, but I wouldn’t worry at those levels. My BG recently hit 600+ Yes, that’s cause for extreme concern. I’ve since gotten it down, with diet, exercise, and meds. My most recent 30-day average was 177, which is still quite high, but on the right track! Op, if I were you, I’d just watch the diet. You can test your own BG, just buy a meter, strips, and lancets. You don’t need a prescription. The RX helps with insurance payment. Try Walmart, they have a cheapie that’s about $15, I think its called Relion --sp? Anyways, OP, you certainly aren’t diabetic, probably not even pre-diabetic . Since the ADA changed their desirable BG numbers a lot of people have been confused. So, this would be my advice-- -try to lose weight -monitor your BG yourself, try to see if there’s any patterns, triggers, etc. - change your eating habits—easier said than done. cut out the sweets, candies, eat regular meals, don’t skip meals, etc Good luck!

Hi @AJS914 - can I ask how did you find out that thalassaemia minor increases the HbA1C?

I have thalassaemia minor as well and registering as borderline normal/prediabetic, but completely no risk factors (fit, no excess fat, exercise 5/6 times a week high intensity, no drinking, no smoking, no family history of diabetes) so I’ve always wondered if thalassaemia might be throwing the readings, but haven’t been able to find anything to support my theory.