Can A Low Carb Diet Cause A False Negative Hba1c Test?

bookworm01

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Hi everyone,

I've been feeling quite run-down (tired and achy, can't focus, constantly thirsty, headache, having to get up at night 5-10 times to urinate) for a good year or so now, although my symptoms have worsened in the last couple of months to the point that I'm really worried about how I'll cope at school (starting year 13 (Upper 6th) in a fortnight, so the important A-level year).

Whenever I eat within half an hour I feel very headachy, tired and dizzy, irritable and I find it really hard to think and concentrate, as if I've taken a sleeping pill. This post-prandial fatigue state used to only bother me after something like a panini, a bowl of pasta or fruit juice, so I started a low carbohydrate diet a few months ago in the hope that I'd feel better. But in the last month or so it has started happening every time I eat. Plus even though I've increased my fat and protein intake I've lost a couple of kilograms which has clearly come from muscle, as you can see a difference in my triceps and quads and I feel weaker. I can't win!

I have a GP appointment tomorrow to speak about this, and hopefully they'll be willing to test my thyroid hormones, fasting glucose, c-peptide and HbA1C. Have I missed any other important tests that should be run to exclude the various causes of my symptoms? Does anyone know if a urine test for glucose would be positive if someone has LADA, and whether the result of that could be affected by a low carb diet?

Finally, as alluded to in the title, I was wondering if anyone is aware of whether having been on a low carbohydrate (thus high fat) diet for a few months could result in my HbA1C or fasting glucose result being low enough to not indicate diabetes type 1.5/LADA (I think this most closely matches my symptoms, but please let me know if you think otherwise!) even if I actually have the condition? I'm worried that the low carb diet will mask the signs of an underlying problem and mean that I have to spend longer feeling unwell before we work out why.

Edit: Can type 1.5 diabetes occur in adolescence and can it come on over a period of a year or two, as my symptoms have, without any significant event (e.g. ketoacidosis)? Or am I more likely getting myself anxious unnecessarily? Could I be suffering from reactive hypoglycaemia and if so, how is one tested and treated for that?
 
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Mr_Pot

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Firstly I would say that until you are diagnosed you don't know that your symptoms are diabetes related although they sound like it. If your symptoms are related to your blood glucose level and you still have the symptoms it seems unlikely that it will not be reflected in your HbA1c.
 
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Juicyj

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Hello @bookworm01 and welcome.

Firstly your diet will not influence your HbA1c result as this result is a measure of your glycated haemoglobin and indicates what your average blood glucose reading is over 4 months, so if it's low that's fine there's no need to worry about diabetes.

However from reading your message you appear to be quite stressed about this, being anxious can affect all areas of your life, so finding a way to relax such as exercise, talking to others, meditation, getting fresh air and sleep will all help contribute to your well being. As long as your GP has ruled out any other probable causes then try and find ways to relax and hopefully your symptoms will ease, best wishes.
 

Mr_Pot

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Firstly your diet will not influence your HbA1c result
I don't think diet controlled type 2's would agree.
The OP has been on a low carb diet for a few months .
My point was that he still has the symptoms, so if they are glucose level related he still has the glucose level.
 

Guzzler

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It has been said that it is the last 4-6 weeks before the test draw is taken that influences the result most.
 

Juicyj

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I don't think diet controlled type 2's would agree.
The OP has been on a low carb diet for a few months .
My point was that he still has the symptoms, so if they are glucose level related he still has the glucose level.

My response was in relation to type 1 diabetes, as the OP is still young and has alluded to type 1.5 indicating this isn't type 2 then I would suggest otherwise, therefore a HbA1C would show an elevated result regardless of diet.

Just also to add that type 1 is diagnosed after feeling very unwell over a short period of time, around 1-2 weeks, other symptoms would include pear breath, presence of high ketones in urine, blurred vision, loss of weight, excessive thirst and peeing (insatiable thirst), other symptoms include dry skin, thrush.

Also I am not a GP I speak only from experience, any symptoms must be checked with a GP.
 

KK123

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Hi there, in answer to your question about could type 1 come on in a year or two, all I know is that I staggered on for a good 8 months or more steadfastly ignoring the excessive thirst. I'm guessing that I must have been 'honeymooning' to some extent, ie my body was still managing to produce insulin of my own.
 

zand

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My response was in relation to type 1 diabetes, as the OP is still young and has alluded to type 1.5 indicating this isn't type 2 then I would suggest otherwise, therefore a HbA1C would show an elevated result regardless of diet.

Just also to add that type 1 is diagnosed after feeling very unwell over a short period of time, around 1-2 weeks, other symptoms would include pear breath, presence of high ketones in urine, blurred vision, loss of weight, excessive thirst and peeing (insatiable thirst), other symptoms include dry skin, thrush.

Also I am not a GP I speak only from experience, any symptoms must be checked with a GP.
Some folks on here have controlled LADA in the early days with diet alone though? So wouldn't this indicate that diet could influence the HbA1c result?
 

Juicyj

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Hi @zand My response is purely in relation to the OP who is a teenager and based the fact that LADA affects adults: https://www.diabetes.co.uk/diabetes_lada.html So if anything, this would indicate the possibility for type 1 being more relevant if this indeed was indicated by the HbA1c result.

Sorry I can't speak from experience in regards to LADA and diet.
 
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EllieM

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I'm pretty sure that if the OP has symptoms of diabetes (thirst, weight loss etc etc) then her hbA1C will be up. The only thing the low carb diet will do is extend the honeymoon period when she can cope without insulin - the symptoms are caused by high blood sugar and if she has high blood sugar then her hbA1C will be up. Having said that, it's possible that the symptoms aren't caused by diabetes at all, but if the doctor does a full set of bloods they should pick up the problem.

I've got to say it, because my daughter had similar issues at the same age (though without the thirst which is why I hope this option is unlikely), restrictive diets for teenagers (particularly but not exclusively girls) and weight loss can result in eating disorders which have nothing to do with anorexia, bulimia or any desire to lose weight. And once your weight goes below a critical level it can become hard to think rationally about food and diet. So I'm a little concerned about whether the low carb diet has enough calories for a growing 17 year old, particularly since I know some of the T2 low carbers on here have trouble keeping their weight up.

In any case, no use theorising on what she has, the GP visit will hopefully clear it up.
Good luck
 
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