Fascinating, thanks. What about carbohydrate restriction as a treatment for people who already have T2D? The Guardian gave a relatively favourable review to Gary Taubes' recent book which made the argument that diabetes treatment has not been sufficiently focused on carb restriction, but Taubes's previous books have not been well-received by nutrition scientists:
It’s an interesting question and perhaps more nuanced than you think. The evidence suggests that in most cases a reductions of carbs in the absence of weight change don’t change plasma glucose concentrations much if at all - unless protein increases too! This is actually research that I run myself. so one of my trials showed that reductions in carb from 30 to 10% of calories made no difference to glucose concentrations with protein kept at 15%. my recent trial that we’ve submitted for publication looked at what happens if we keep carbohydrate constant at 20% of calories and double the protein from 15 to 30% of calories - and what we see is that glucose significantly reduces. In practice (in the real world) when people cut carbs, they tend to also increase protein, and in fact anecdotally when I talk to people who’ve had great success from a nominal low carbohydrate diet, they actually consume a lot more protein and I think it’s the protein that’s the “active ingredient”.
But there is a bit more nuance here in that if people go low-carb, they tend to lose weight, which is obviously good for type 2 diabetes management. The other bit of nuance is that if you cut carbs low enough such that you are now generating ketones, it seems that the ketones themselves suppress glucose output, without weight loss or extra protein.
This is interesting! Would these different mechanisms be at play in all T2D or are there subgroups where each or a combination of mechanisms predominate? So many more questions! As a primary care doctor I see very individual responses for different people with pre-diabetes and T2D.
I don’t have a medical background but can readily follow your articles. Im 69 years old and a heavy exerciser. Most of your articles are of keen interest to me. Keep up the excellent work.
Thank you very much! I’m really glad. I never want to oversimplify things because physiology is not straightforward (!) but I always worry might be too jargon-y for some. So I am glad you find the articles useful!
Great article! Also this: "30 mins cycling twice a day at 120W". Sounds like a bike commute to me! (Although my bike commute is more like 50 mins riding time each way.)
Thank you for this! Your posts regarding athletes and glucose issues have helped me find a more informed way forward as a life-long (50+ years at it!) long distance runner, vegetarian, with very low BMI, and yet a recent A1c-based prediabetes diagnosis.
Wondering if you have any thoughts regarding the latest research on the Triglyceride-Glucose Index as an alternative to the A1c test?
My husband is a past marathon runner and 68 years old. He's continued to bike long rides, hike many miles and do other cardio often. He's lean and fit. He was eating pumpernickel bread, lots of dried apricots, oats and soy milk, and otherwise very whole food diet. His A1C was 5.8 and his CAC over 300. What's a lean person to do? Their small fat stores fill and spill into visceral. He chose Keto. A1C is now 5.4. We'll have to track CAC or get a CCTA. I've seen this in friends, especially Asian. Lean people.
Hi Dr. Guess! First off, really want to thank you for putting out such high quality science-based content on diabetes (especially for free on the blog). I've read most of your work and have certainly learned a lot! There's 2 particular things that I'm quite curious about that don't seem to be covered on other resources online (or in your blog) so I'm curious if you could share your thoughts on them.
The two things are:
1. Is there a good explanation for why the pre-diabetic and diabetic cutoffs for both fasting glucose and a1c between the US and UK/WHO/AUS are so different? If I were to interpret my own data to inform my health decisions -- which would make more sense to use?
2. I've read your article on why atheletes may have pre-diabetes (despite being healthy) and may result in a high fasting glucose but normal a1c. But are there reasons why somebody might have artificially inflated A1C and still have normal glucose tolerance and control? I'm consistently getting a 5.7% a1c readings with fasting glucose around 80 from my routine blood and lab work. However, after a few months of data gathering via CGM, I'm seeing 2 hour post prandials under 140 mg/dl (which is a good indicator of healthy glucose function from my readings of your blogs), fasting glucoses of 75-85 mg/dl, and my average glucose for the entire 1 day, 7 day, 14 day, and 29 day durations of 90 mg/dl.
Is there any reasonable explanation for 2)? The only thing I can think of is red blood cell life span being very high (as I understand the variability between individuals can be very high), leading to more blood glucose accumulation in the blood cells and causing elevated a1c.
I'm a cardiologist not an endocrinologist so my info on this is as a lay person. I have prediabetes apparently with an A1c of 6.1. That suggests a higher than normal average blood glucose. Several studies have shown that this increases risk for cardiovascular disease. So I'm trying to lower my average glucose with reduced carbs intake. I'm also an athlete (running, cycling). I'm 75, 140 lbs and 5ft 8in. I have a calcium score of ZERO. Taking a statin anyway. My internist put me on Jardiance which didn't budge my mean glucose or A1c. Now I'm on metformin 1000mg a day. We'll see what that does. Your article makes me wonder if I should just stop everything.
Question, and I'm out of my wheelhouse for sure, but I'm going to ask anyway.
"Sugar" causes inflammation. I found this out when I was diagnosed with Psoriatic Arthritis. I have done myself a favor my removing added sugars from my diet.
You do mention inflammation in your article, and how inflammation can be a part of T2D "forming".
Is there a way to look at how much inflammation is forming in the body due to ingesting "sugars" for athletes?
With everything you said about whole foods, I can't see 10-20 years of ingesting gels and bars good for the longevity of an athlete. Maybe performance on a day of competition is worth it, but the way most weekend warriors consume supplements seems to be excessive.
Thanks for the article. This is a topic I want to see more discussions and studies around.
This comprehensive analysis encompassed 18 cohort studies with a total of 607,882 participants and 29,228 T2D cases. The study concluded that carbohydrate intake within the recommended range of 45% to 65% of total caloric intake was not linked to an increased risk of T2D. However, when carbohydrate consumption exceeded 70% of total calories, a significant increase in T2D risk was observed, particularly in Asian populations where such dietary patterns are more prevalent. The authors noted that these findings are based on observational data, which cannot establish causality, and emphasized the need for further research in regions with high carbohydrate consumption.
I would be cautious about these observational studies particularly in Asian populations. Typically a very high carbohydrate intake is more common in poor or rural areas - and accordingly their diet tends to be low or deficient in foods like meat, dairy, legumes and some micronutrients.
Similarly the very high carbohydrate diets tend to be more commonly consumed in older populations who themselves are at higher risk of type two diabetes anyway. While you can adjust somewhat in observational studies for these factors (I am not an epidemiologist!) I don’t think you can completely.
So I’m sceptical that it’s the high carbohydrate here that’s having the effect, I think it’s more likely to be a combination of malnutrition, poverty and perhaps aging.
I also struggle with what the mechanism could be given that we have good control trials which gave people up to 80% of calories from glucose with 15% of calories from Protein, with no change in blood glucose compared to 60% of calories from glucose for example. What we think happens is there as starch or glucose intake goes up, insulin sensitivity increases in turn. There’s definitely a bit of grey here in terms of people with existing metabolic syndrome or insulin resistant respond to carbs, and for reasons we don’t fully understand yet people from Asian and South Asian ethnic backgrounds are at greater risk of type two diabetes. So maybe there is something in some populations that could mean that a high carbohydrate diet could promote type to Diabetes development but I’m pretty sceptical.
The only endurance athlete I've seen with potential metabolic problems regarding this is Lachlan: https://www.youtube.com/watch?v=sFGP847dGxE (6.6 mmol / L fasting in the morning)
His previous diet was 100% processed carbs, he has a video on it as well.
Very interesting, thank you. I think one of the challenges with knowing what is causing type 2 diabetes in different individuals is that it’s such a heterogeneous disease. The stuff that can go wrong depends on a lot of genetics and Epigenetics which might affect the beta cells and/or the liver and/or the muscle in different ways. Like I laid out in this piece, I think athletes are really protected from type 2 diabetes, but in some people the genetics is so “strong” that no matter what they do in terms of diet and exercise their glucose goes up anyway. It’s also worth mentioning that we recognise different kinds of diabetes that aren’t Type 1 or type two diabetes, and this is a fairly new field. Many people may think they have or be diagnosed with type 2 diabetes and actually have monogenic diabetes: eg https://www.diabetes.org.uk/about-diabetes/other-types-of-diabetes/mody
Great question and I don’t think we know. Of course I would say it’s more about adiposity particularly central adiposity so I would imagine waist circumference is a much better measure of BMI, but it’s hard to know at what degree of central adiposity someone would start being at higher risk of insulin resistance from fructose or even high starch intake. However, I would tend towards being reassured by the Luc Tappy paper in which even in the face of a pretty large calorie excess and whacking amount of fructose that even such a moderate amount of physical activity was able to basically ameliorate the negative effects found in people not doing the moderate activity.
In my cohort, we are extreme outliers for sugar consumption. I smiled when I read the grams of CHO in your article. It would not be unusual for us to consume 500g of carbs (nearly all sugars) on a big day of training. When racing events, such as Ironman, the larger males will eat (mostly by drinking) up to 1,000g across the day.
There’s an old school paper about dietary intake in Tour De France cyclists and they were having something like 400-500g of simple (as we called them in those days) sugars - most of it was liquid. That didn’t include starches. So yeah in total it was about 6000kcal and nearly a kg of carb. Us mere mortals have NO IDEA. lol.
I take from this that extreme diets (keto) are not good and the best thing is fibre, protein, whole foods, three meals a day, portion control, don’t binge on sugar too often. Very unexciting but kind of reassuring. Thank you for the work.
Fascinating, thanks. What about carbohydrate restriction as a treatment for people who already have T2D? The Guardian gave a relatively favourable review to Gary Taubes' recent book which made the argument that diabetes treatment has not been sufficiently focused on carb restriction, but Taubes's previous books have not been well-received by nutrition scientists:
https://www.theguardian.com/society/2024/jan/14/unlocking-the-truth-about-diabetes-is-it-time-for-a-diet-based-treatment
It’s an interesting question and perhaps more nuanced than you think. The evidence suggests that in most cases a reductions of carbs in the absence of weight change don’t change plasma glucose concentrations much if at all - unless protein increases too! This is actually research that I run myself. so one of my trials showed that reductions in carb from 30 to 10% of calories made no difference to glucose concentrations with protein kept at 15%. my recent trial that we’ve submitted for publication looked at what happens if we keep carbohydrate constant at 20% of calories and double the protein from 15 to 30% of calories - and what we see is that glucose significantly reduces. In practice (in the real world) when people cut carbs, they tend to also increase protein, and in fact anecdotally when I talk to people who’ve had great success from a nominal low carbohydrate diet, they actually consume a lot more protein and I think it’s the protein that’s the “active ingredient”.
But there is a bit more nuance here in that if people go low-carb, they tend to lose weight, which is obviously good for type 2 diabetes management. The other bit of nuance is that if you cut carbs low enough such that you are now generating ketones, it seems that the ketones themselves suppress glucose output, without weight loss or extra protein.
This is interesting! Would these different mechanisms be at play in all T2D or are there subgroups where each or a combination of mechanisms predominate? So many more questions! As a primary care doctor I see very individual responses for different people with pre-diabetes and T2D.
This is great 👍
Cheers mate
I don’t have a medical background but can readily follow your articles. Im 69 years old and a heavy exerciser. Most of your articles are of keen interest to me. Keep up the excellent work.
Thank you very much! I’m really glad. I never want to oversimplify things because physiology is not straightforward (!) but I always worry might be too jargon-y for some. So I am glad you find the articles useful!
I love your work! So informative, easy to understand, & super interesting! I'm a huge fan! Would love to meet you one day!
Thank you very very much!
Great article! Also this: "30 mins cycling twice a day at 120W". Sounds like a bike commute to me! (Although my bike commute is more like 50 mins riding time each way.)
Yes exactly!, And it’s pretty low intensity so a brisk 30 minute walk to work or college and back again would also fit the bill, I would imagine.
Thank you for this! Your posts regarding athletes and glucose issues have helped me find a more informed way forward as a life-long (50+ years at it!) long distance runner, vegetarian, with very low BMI, and yet a recent A1c-based prediabetes diagnosis.
Wondering if you have any thoughts regarding the latest research on the Triglyceride-Glucose Index as an alternative to the A1c test?
My husband is a past marathon runner and 68 years old. He's continued to bike long rides, hike many miles and do other cardio often. He's lean and fit. He was eating pumpernickel bread, lots of dried apricots, oats and soy milk, and otherwise very whole food diet. His A1C was 5.8 and his CAC over 300. What's a lean person to do? Their small fat stores fill and spill into visceral. He chose Keto. A1C is now 5.4. We'll have to track CAC or get a CCTA. I've seen this in friends, especially Asian. Lean people.
Hi Dr. Guess! First off, really want to thank you for putting out such high quality science-based content on diabetes (especially for free on the blog). I've read most of your work and have certainly learned a lot! There's 2 particular things that I'm quite curious about that don't seem to be covered on other resources online (or in your blog) so I'm curious if you could share your thoughts on them.
The two things are:
1. Is there a good explanation for why the pre-diabetic and diabetic cutoffs for both fasting glucose and a1c between the US and UK/WHO/AUS are so different? If I were to interpret my own data to inform my health decisions -- which would make more sense to use?
2. I've read your article on why atheletes may have pre-diabetes (despite being healthy) and may result in a high fasting glucose but normal a1c. But are there reasons why somebody might have artificially inflated A1C and still have normal glucose tolerance and control? I'm consistently getting a 5.7% a1c readings with fasting glucose around 80 from my routine blood and lab work. However, after a few months of data gathering via CGM, I'm seeing 2 hour post prandials under 140 mg/dl (which is a good indicator of healthy glucose function from my readings of your blogs), fasting glucoses of 75-85 mg/dl, and my average glucose for the entire 1 day, 7 day, 14 day, and 29 day durations of 90 mg/dl.
Is there any reasonable explanation for 2)? The only thing I can think of is red blood cell life span being very high (as I understand the variability between individuals can be very high), leading to more blood glucose accumulation in the blood cells and causing elevated a1c.
Any comments on these, and thank you Dr. Guess!
I'm a cardiologist not an endocrinologist so my info on this is as a lay person. I have prediabetes apparently with an A1c of 6.1. That suggests a higher than normal average blood glucose. Several studies have shown that this increases risk for cardiovascular disease. So I'm trying to lower my average glucose with reduced carbs intake. I'm also an athlete (running, cycling). I'm 75, 140 lbs and 5ft 8in. I have a calcium score of ZERO. Taking a statin anyway. My internist put me on Jardiance which didn't budge my mean glucose or A1c. Now I'm on metformin 1000mg a day. We'll see what that does. Your article makes me wonder if I should just stop everything.
A handful of questions:
- What's your logic for being on a statin?
- What's your fasted blood glucose?
- What's your general eating pattern (times and foods?)
Question, and I'm out of my wheelhouse for sure, but I'm going to ask anyway.
"Sugar" causes inflammation. I found this out when I was diagnosed with Psoriatic Arthritis. I have done myself a favor my removing added sugars from my diet.
You do mention inflammation in your article, and how inflammation can be a part of T2D "forming".
Is there a way to look at how much inflammation is forming in the body due to ingesting "sugars" for athletes?
With everything you said about whole foods, I can't see 10-20 years of ingesting gels and bars good for the longevity of an athlete. Maybe performance on a day of competition is worth it, but the way most weekend warriors consume supplements seems to be excessive.
Thanks for the article. This is a topic I want to see more discussions and studies around.
If you eat too many carbs do they not increase one's calories?
Sci Rep. 2022 Feb 15;12:2491. doi: 10.1038/s41598-022-06212-9
Systematic Review and Meta-Analysis:
This comprehensive analysis encompassed 18 cohort studies with a total of 607,882 participants and 29,228 T2D cases. The study concluded that carbohydrate intake within the recommended range of 45% to 65% of total caloric intake was not linked to an increased risk of T2D. However, when carbohydrate consumption exceeded 70% of total calories, a significant increase in T2D risk was observed, particularly in Asian populations where such dietary patterns are more prevalent. The authors noted that these findings are based on observational data, which cannot establish causality, and emphasized the need for further research in regions with high carbohydrate consumption.
I would be cautious about these observational studies particularly in Asian populations. Typically a very high carbohydrate intake is more common in poor or rural areas - and accordingly their diet tends to be low or deficient in foods like meat, dairy, legumes and some micronutrients.
Similarly the very high carbohydrate diets tend to be more commonly consumed in older populations who themselves are at higher risk of type two diabetes anyway. While you can adjust somewhat in observational studies for these factors (I am not an epidemiologist!) I don’t think you can completely.
So I’m sceptical that it’s the high carbohydrate here that’s having the effect, I think it’s more likely to be a combination of malnutrition, poverty and perhaps aging.
I also struggle with what the mechanism could be given that we have good control trials which gave people up to 80% of calories from glucose with 15% of calories from Protein, with no change in blood glucose compared to 60% of calories from glucose for example. What we think happens is there as starch or glucose intake goes up, insulin sensitivity increases in turn. There’s definitely a bit of grey here in terms of people with existing metabolic syndrome or insulin resistant respond to carbs, and for reasons we don’t fully understand yet people from Asian and South Asian ethnic backgrounds are at greater risk of type two diabetes. So maybe there is something in some populations that could mean that a high carbohydrate diet could promote type to Diabetes development but I’m pretty sceptical.
Thanks for your lengthy response. As they say “as clear as mud.”
The only endurance athlete I've seen with potential metabolic problems regarding this is Lachlan: https://www.youtube.com/watch?v=sFGP847dGxE (6.6 mmol / L fasting in the morning)
His previous diet was 100% processed carbs, he has a video on it as well.
Very interesting, thank you. I think one of the challenges with knowing what is causing type 2 diabetes in different individuals is that it’s such a heterogeneous disease. The stuff that can go wrong depends on a lot of genetics and Epigenetics which might affect the beta cells and/or the liver and/or the muscle in different ways. Like I laid out in this piece, I think athletes are really protected from type 2 diabetes, but in some people the genetics is so “strong” that no matter what they do in terms of diet and exercise their glucose goes up anyway. It’s also worth mentioning that we recognise different kinds of diabetes that aren’t Type 1 or type two diabetes, and this is a fairly new field. Many people may think they have or be diagnosed with type 2 diabetes and actually have monogenic diabetes: eg https://www.diabetes.org.uk/about-diabetes/other-types-of-diabetes/mody
I love how clear and precise you are.
Thanks for writing this.
When you write "pretty lean" in the context of an endurance athlete, would you link to a healthy BMI?
Or do you evaluate using different metrics?
Thanks,
G
Great question and I don’t think we know. Of course I would say it’s more about adiposity particularly central adiposity so I would imagine waist circumference is a much better measure of BMI, but it’s hard to know at what degree of central adiposity someone would start being at higher risk of insulin resistance from fructose or even high starch intake. However, I would tend towards being reassured by the Luc Tappy paper in which even in the face of a pretty large calorie excess and whacking amount of fructose that even such a moderate amount of physical activity was able to basically ameliorate the negative effects found in people not doing the moderate activity.
Thanks.
In my cohort, we are extreme outliers for sugar consumption. I smiled when I read the grams of CHO in your article. It would not be unusual for us to consume 500g of carbs (nearly all sugars) on a big day of training. When racing events, such as Ironman, the larger males will eat (mostly by drinking) up to 1,000g across the day.
g
There’s an old school paper about dietary intake in Tour De France cyclists and they were having something like 400-500g of simple (as we called them in those days) sugars - most of it was liquid. That didn’t include starches. So yeah in total it was about 6000kcal and nearly a kg of carb. Us mere mortals have NO IDEA. lol.
I take from this that extreme diets (keto) are not good and the best thing is fibre, protein, whole foods, three meals a day, portion control, don’t binge on sugar too often. Very unexciting but kind of reassuring. Thank you for the work.
in medio stat virtus