Heart Problems associated with having ow blood glucoses

[crazyhenlady]

I just wondered if anyone has any evidence that keeping your blood sugars low end of normal and sometimes dipping below 4mmol/l is harmful to your heart.

My DSN is obsessed with this and yet has no evidence other than the ACCORD study.

I am type 1 and have been for 44 years . I have recently been given the libre monitoring system on trial for 6 months on the NHS and hence now having to see a nurse designated experienced enough to monitor readings etc.
I eat lchf and am on insulin and am a keen runner. I have average daily hba1c estimations of 6mmol/l with the libre. I do occasionally have a libre reading of 3.5 to 4mmol/l which I correct with Lucozade ( it works nicely for me) . I never get unable to function or feel bad when readings are this low. In fact I feel worse when they go over 8mmol/l .

However DSN is not happy about this and is insistent I'm damaging my heart?? I would like reassurance that this is not likely and thinking long term I'd rather take my chances than risk neuropathy complications.
Has anyone else experienced any professionals telling them this? Or know any evidence other than the flawed ACCORD ? Study

 

[kitedoc]

Hi @crazyhenlady, from my reading as a T1D, not as professional advice or opinion.
As you infer the ACCORD study seems to have made a strong impression on health professionals.
The mantra has become, keep HBA1cs between 6 and 7 % ( 42 to 53 mmol/l) though I have heard this creep up to 7.5 % (58 mmol/mol). (for T1Ds anyway). No one appears sure about why below 6 (42) that cardio-vascular problems incidence increased.
Of course, there is the fact that the majority of subjects were T2D, which adds in the confounder of unknown time with high BSLs and who knows what HBA1Cs before diabetes diagnosis.
Yes hypos are an obvious 'cause' of increased mortality to latch on to for patients with HBA1Cs below 6 (42).
The other is conjecture that to achieve lower HBA1Cs requires either larger doses of insulin in the T1Ds and those T2Ds on insulin or maybe larger doses or exposure to sulphonylurea drugs with their propensity to increase heart problems. (and assuming that subjects may have been adhering to the 'good, old' high carb ADA diet).
But to pontificate in a study report on such a diet as a potential cause or contributor to adverse findings might harm the reputation of the ADA, and that would never do!!
And, as you note, these studies/review were conducted before wider spread use of CGM and likely with few being on low carb high fat diets.
It would be wonderful to quote Dr Richard Bernstein's personal experience as a foil against the "too low HBA1C" mantra, but his example is reduced by the 'power of statistics' to a figure of one.
And studies which for statistical purposes, divide up study groups into intervals of %age HBA1Cs, e.g. 6 to 7 % etc do not tell us whether it is better to be nearer the 6%(42) or the 7 % (53) and if the risk, on their analysis, is the same if your HBA1C were 5 .9 (40)or say, 5.4 (36). And the actual ranges of BSL variation are dismissed in adherence to using the averaging measurement of HBA1C.
Nor do we know whether variability in haemoglobulin type and other causes of inaccurate HBA1C estimation were taken into account.
Hopefully, with better monitoring and lower incidence of hypos, and more acceptance of lower carb intake diets, HCPs can be persuaded, cajoled into accepting lower HBA1Cs.
But who has the courage to undertake a new study ? Or will it take the persistence of those who pursue lower HBA1Cs to show whether the ACCORD study is not the "gold standard"? But that could take years !!!

 

[hankjam]

I'm no physiologist and can't really offer an opinion but I would be interested to know how the DSN comes to her conclusion...
low blood sugars is generally a "good thing".

Do you finger test to check that the lows really are that low?

Good luck

 

[EllieM]

No one appears sure about why below 6 (42) that cardio-vascular problems incidence increased.

I would have thought that death through an extreme hypo would be a pretty extrem cardiovascular problem? But presumably with the advent of cgms you can set alarms so that extreme hypos don't happen....?
I'd be very cautious about comparing outcomes for T1s and T2s as though some of the symptoms (high blood sugars) are the same, the causes and treatments seem to be so different....

 

[desidiabulum]

My heart surgeon is emphatic that keeping BGs low is more important than anything else I can do. I would have thought that control is key, keeping numbers steady and avoiding hypos (it makes sense that massively fluctuating BGs and lost of hypos would damage the heart). The ACCORD study has been utterly discredited. I would follow advice of DSN on topics they seem well informed about, and politely ignore on topics where they are ignorant.

 

[kitedoc]

I would have thought that death through an extreme hypo would be a pretty extrem cardiovascular problem? But presumably with the advent of cgms you can set alarms so that extreme hypos don't happen....?
I'd be very cautious about comparing outcomes for T1s and T2s as though some of the symptoms (high blood sugars) are the same, the causes and treatments seem to be so different....

Hi @EllieM, That is my point, that having a mix of of T1D and T2D confounds the findings. And an extreme hypo causing death is an obvious cause but that could still happen to someone with a HBA1C above 42.

 

[crazyhenlady]

Hi @crazyhenlady, from my reading as a T1D, not as professional advice or opinion.
As you infer the ACCORD study seems to have made a strong impression on health professionals.
The mantra has become, keep HBA1cs between 6 and 7 % ( 42 to 53 mmol/l) though I have heard this creep up to 7.5 % (58 mmol/mol). (for T1Ds anyway). No one appears sure about why below 6 (42) that cardio-vascular problems incidence increased.
Of course, there is the fact that the majority of subjects were T2D, which adds in the confounder of unknown time with high BSLs and who knows what HBA1Cs before diabetes diagnosis.
Yes hypos are an obvious 'cause' of increased mortality to latch on to for patients with HBA1Cs below 6 (42).
The other is conjecture that to achieve lower HBA1Cs requires either larger doses of insulin in the T1Ds and those T2Ds on insulin or maybe larger doses or exposure to sulphonylurea drugs with their propensity to increase heart problems. (and assuming that subjects may have been adhering to the 'good, old' high carb ADA diet).
But to pontificate in a study report on such a diet as a potential cause or contributor to adverse findings might harm the reputation of the ADA, and that would never do!!
And, as you note, these studies/review were conducted before wider spread use of CGM and likely with few being on low carb high fat diets.
It would be wonderful to quote Dr Richard Bernstein's personal experience as a foil against the "too low HBA1C" mantra, but his example is reduced by the 'power of statistics' to a figure of one.
And studies which for statistical purposes, divide up study groups into intervals of %age HBA1Cs, e.g. 6 to 7 % etc do not tell us whether it is better to be nearer the 6%(42) or the 7 % (53) and if the risk, on their analysis, is the same if your HBA1C were 5 .9 (40)or say, 5.4 (36). And the actual ranges of BSL variation are dismissed in adherence to using the averaging measurement of HBA1C.
Nor do we know whether variability in haemoglobulin type and other causes of inaccurate HBA1C estimation were taken into account.
Hopefully, with better monitoring and lower incidence of hypos, and more acceptance of lower carb intake diets, HCPs can be persuaded, cajoled into accepting lower HBA1Cs.
But who has the courage to undertake a new study ? Or will it take the persistence of those who pursue lower HBA1Cs to show whether the ACCORD study is not the "gold standard"? But that could take years !!!

Thank you for your detailed reply. kitedoc.
I agree that this study has so many variable and none really relevant to T1 diabetics.
Let's us hope that as individuals we can prove that keeping in as near as normal BG range as possible and using sensible lchf diets and monitoring to adjust medication that we are reducing the risk heart disease!!

 

[crazyhenlady]

I'm no physiologist and can't really offer an opinion but I would be interested to know how the DSN comes to her conclusion...
low blood sugars is generally a "good thing".

Do you finger test to check that the lows really are that low?

Good luck

Yes. In fact a 3.5 reading last night on libre was 4.2 mmol/l on blood test so although low was quite a way off. I did test again after10 mins to see if interstitial levels were delayed but came out as same readings!

 

[EllieM]

Yes. In fact a 3.5 reading last night on libre was 4.2 mmol/l on blood test so although low was quite a way off. I did test again after10 mins to see if interstitial levels were delayed but came out as same readings!

The libre is useful, but I'd trust glucometer readings over its ones any day (or night). It reads well for some people but for others it can be very inaccurate, and under reading at low blood sugars is definitely a thing. It sounds like your control is excellent. If your low readings are off by even 10% then you could never be reaching true hypo levels. (Plenty of non diabetics get readings of 3.8 when fasting, it's not a problem because they're not at risk of going lower....)

 

[crazyhenlady]

The libre is useful, but I'd trust glucometer readings over its ones any day (or night). It reads well for some people but for others it can be very inaccurate, and under reading at low blood sugars is definitely a thing. It sounds like your control is excellent. If your low readings are off by even 10% then you could never be reaching true hypo levels. (Plenty of non diabetics get readings of 3.8 when fasting, it's not a problem because they're not at risk of going lower....)

Thank you. That is reassuring. I will go by the blood glucose readings then and not worry so much.

 

[Mbaker]

I am not sure, but there might be heart disease / risk numbers in the Type 1 Grit trial. It would potentially satisfy your question as this is exclusively Type 1's. The difference to your diet may just be that their version of low carb, leans more towards increased protein than fat. May even be worth you joining and posing the same question.

 

[slip]

I read your post crazyhenlady and wasn't going to reply as you've had some great responses anyway, but obviously I am responding now in part because of your name (do you keep chickens? I do).

I wanted to also say that you chose your words careful when describing your nurse as she obviously isn't an expert - if you can backup with blood tests that the libre reads lower especially at the low end of the scale and she should already be aware of this if she was and that this throws her argument out the windows straight off. Never mind that T0s can and do drop below 4mmol, and with that in mind I'd ask her is she would be willing to wear a Libre to see how much damage she is doing to her own heart before she makes any further comments!

 

[NicoleC1971]

I just wondered if anyone has any evidence that keeping your blood sugars low end of normal and sometimes dipping below 4mmol/l is harmful to your heart.

My DSN is obsessed with this and yet has no evidence other than the ACCORD study.

I am type 1 and have been for 44 years . I have recently been given the libre monitoring system on trial for 6 months on the NHS and hence now having to see a nurse designated experienced enough to monitor readings etc.
I eat lchf and am on insulin and am a keen runner. I have average daily hba1c estimations of 6mmol/l with the libre. I do occasionally have a libre reading of 3.5 to 4mmol/l which I correct with Lucozade ( it works nicely for me) . I never get unable to function or feel bad when readings are this low. In fact I feel worse when they go over 8mmol/l .

However DSN is not happy about this and is insistent I'm damaging my heart?? I would like reassurance that this is not likely and thinking long term I'd rather take my chances than risk neuropathy complications.
Has anyone else experienced any professionals telling them this? Or know any evidence other than the flawed ACCORD ? Study

Briefly I went to a diabetes education course in order to get my FSL and asked the consultant if there was any physiological damage caused by having too low blood sugars. She mentioned that it is associated with some heart problems but also that going to low may lead to lack of hypo warnings.
I do not think she knew how this works for heart issues (she mentioned an associated with abnormal heart rythmns) in the context of a low carb diet in which insulin is also low; if you believe that too much insulin as well as high bgs (glycation) is a risk factor as many do then this is important.
Re hypos, I think Volek and Phinney did keto experiments on athletes in which they tolerated much lower bgs without having symptoms of hypos. I certainly notice that if my control improves my threshold for tolerating a low gets lower i.e. when running high I notice a hypo at 5 and when achieving good control, that goes down to 3.5 or so.
However clinicians treating with insulin are going to be cautious about hypos and assume that in having great blood glucose control you are on a roller coaster. Hopefully the fsl will allow you to show plenty of time in the correct range!
Here's a google scholar link for what it is worth (I just typed in hypoglycemia and cardivascular risk)
https://scholar.google.co.uk/schola...a+and+cardiovascular+risk&oq=hypoglycemia+and

 

[crazyhenlady]

Briefly I went to a diabetes education course in order to get my FSL and asked the consultant if there was any physiological damage caused by having too low blood sugars. She mentioned that it is associated with some heart problems but also that going to low may lead to lack of hypo warnings.
I do not think she knew how this works for heart issues (she mentioned an associated with abnormal heart rythmns) in the context of a low carb diet in which insulin is also low; if you believe that too much insulin as well as high bgs (glycation) is a risk factor as many do then this is important.
Re hypos, I think Volek and Phinney did keto experiments on athletes in which they tolerated much lower bgs without having symptoms of hypos. I certainly notice that if my control improves my threshold for tolerating a low gets lower i.e. when running high I notice a hypo at 5 and when achieving good control, that goes down to 3.5 or so.
However clinicians treating with insulin are going to be cautious about hypos and assume that in having great blood glucose control you are on a roller coaster. Hopefully the fsl will allow you to show plenty of time in the correct range!
Here's a google scholar link for what it is worth (I just typed in hypoglycemia and cardivascular risk)
https://scholar.google.co.uk/schola...a+and+cardiovascular+risk&oq=hypoglycemia+and

Thank you Nicole . That I can tolerate much lower blood glucose levels when I have tight control is definetely true. I will continue to investigate any studies that are harmful for heart health in relation to running low blood glucose levels and post on here.

 

[crazyhenlady]

I read your post crazyhenlady and wasn't going to reply as you've had some great responses anyway, but obviously I am responding now in part because of your name (do you keep chickens? I do).

I wanted to also say that you chose your words careful when describing your nurse as she obviously isn't an expert - if you can backup with blood tests that the libre reads lower especially at the low end of the scale and she should already be aware of this if she was and that this throws her argument out the windows straight off. Never mind that T0s can and do drop below 4mmol, and with that in mind I'd ask her is she would be willing to wear a Libre to see how much damage she is doing to her own heart before she makes any further comments!

Yes slip...I have 8 ex caged hens at the moment who I adore. I volunteer with British Hen Welfare Trust rescues and always come away with at least one hen who needs extra tlc. They are so lovely natured. What hens do you have?
I think my dsn should be less obsessive about my lows and be positive that I have tight control ...grrr she seems to think that 8 to 12mmol/l are fine short term even though I told her I feel dreadful when reading are that high. Wish she would leave me to it as I know me better than anyone

 

[slip]

Currently have 6 hens, a cornish game, a welsumer, a red white and blue french breed I can't remember the name of, and 3 various hybrids - started about 11 years ago with a mix of 3 light and red sussex, the cornish, welsumer and french we hatched at various times and the most I've had is 9 at any one point - I'd have more but.....space! (the run and house could take more but I don't like to stock them anywhere near as dense as 'they' say). And besides with more hens I'd spend more time just watching them instead of doing other things - they are total time wasters!

Remember you're unique, your DSN has to 'go with the majority' and on the whole most T1Ds can and do hit the 8-12mmol mark without issue, you on the other hand don't, I think her comments could be marked as '*delete where appropriate' as far as you're concerned

 

[crazyhenlady]

Just made some delicious psyllium husk pancakes with their eggs too. I know what you mean about time wasters...but I always think they make me keep things in perspective. Going to
* delete where appropriate her comments myself

 

[NicoleC1971]

Thank you Nicole . That I can tolerate much lower blood glucose levels when I have tight control is definetely true. I will continue to investigate any studies that are harmful for heart health in relation to running low blood glucose levels and post on here.

Let us know what you find. I am trying to keep my bgs tight on the basis that higher sugars are more damaging to my heart than lower 'hypo' ones. Not that I am anywhere near your levels so kudos to you.

 

[SimonCrox]

I think there are several factors here.

Glucose levels in the normal range are probably better than gluocse values in the higher range for the heart, but in effect UKPDS, ACCORD, Veterans study did not show this. DCCT trial really did not show harm from hypos. Most of the work is in type 2's

With hypos, it is probably more the speed of drop of gluocse than the low value per se.
DeSouza et al 2006 put CGMs and continuous ECG monitors on T2DM folk and found that when the gluocse dropped 5.5 mmol/L or more in 60 minutes, this was assoicated with ECG changes or symptoms of coronary ischaemia.
As folk say, the ACCORD study really highlighted this, in the BMJ 2010 paper, if one had intensive treatment, one was more likely to go hypo, but on less intensive treatment, a hypo was more likely to be fatal than a hypo on intensive treatment. But there will always be the problem that perhaps the subject was at risk and that is why they had the hypo and the adverse event
In ADVANCE, Zoungas 2010, severe hypos were assoicaed with heart attacks and mortality, but the authors concluded that the hypos and MIs and deaths were all due to frailty.

But in T2DM, also the class of drugs may (or may not) be beneficial for the heart via mechanisms other than glucose lowering eg pioglitazone, the SGLT-2 inhibitors and liraaglutide/semaglutide avoid heart attacks.

And there are always the dead in bed stories and the ECG findings in hypoglycaemia which I am not very familiar with, but are generally in marked hypoglycaemia

At the end of the day, one wants to avoid hypos for various reasons, but running on low normal levels and being used to them and only dropping a bit into the hypo range and having hypo awareness looks OK to me..

Best wishes

 

[crazyhenlady]

I think there are several factors here.

Glucose levels in the normal range are probably better than gluocse values in the higher range for the heart, but in effect UKPDS, ACCORD, Veterans study did not show this. DCCT trial really did not show harm from hypos. Most of the work is in type 2's

With hypos, it is probably more the speed of drop of gluocse than the low value per se.
DeSouza et al 2006 put CGMs and continuous ECG monitors on T2DM folk and found that when the gluocse dropped 5.5 mmol/L or more in 60 minutes, this was assoicated with ECG changes or symptoms of coronary ischaemia.
As folk say, the ACCORD study really highlighted this, in the BMJ 2010 paper, if one had intensive treatment, one was more likely to go hypo, but on less intensive treatment, a hypo was more likely to be fatal than a hypo on intensive treatment. But there will always be the problem that perhaps the subject was at risk and that is why they had the hypo and the adverse event
In ADVANCE, Zoungas 2010, severe hypos were assoicaed with heart attacks and mortality, but the authors concluded that the hypos and MIs and deaths were all due to frailty.

But in T2DM, also the class of drugs may (or may not) be beneficial for the heart via mechanisms other than glucose lowering eg pioglitazone, the SGLT-2 inhibitors and liraaglutide/semaglutide avoid heart attacks.

And there are always the dead in bed stories and the ECG findings in hypoglycaemia which I am not very familiar with, but are generally in marked hypoglycaemia

At the end of the day, one wants to avoid hypos for various reasons, but running on low normal levels and being used to them and only dropping a bit into the hypo range and having hypo awareness looks OK to me..

Best wishes

Thank you SimonCrox . I have read the various studies done and come to the same conclusion. My hypos are infrequent and not severe. I am aware of them and can correct them easily. I cannot feel my heart significantly change rate so i'm not going to change things at the moment .