There’s a revolution in the way diabetes is being diagnosed, and if you are someone considered at high risk of developing diabetes, the medical providers you come in contact with are going to want to test you for diabetes, so it’s valuable information to have. And let me say right now that I’m not a doctor, and this is no substitute for appropriate medical advice for you by a professional, so please, if you are worried about something, see a professional. My expertise comes from having diabetes and studying it, and working in the field of diabetes public health.
The article I’m going to be talking about can be downloaded here, so you can follow along at home. Also, people who measure blood glucose in mmol/l will need to look up the numbers themselves in this article. Sorry!
An International Expert Committee with members appointed by the American Diabetes Association, the European Association for the Study of Diabetes, and the International Diabetes Federation was convened in 2008 to consider the current and future means of diagnosing diabetes (outside of pregnancy). A statement from this committee was released online June 5, 2009. This statement was meant to promote discussion of using the A1C test, rather than the current diagnostic criteria, to diagnose diabetes.
There are differences between how type 1 and type 2 are diagnosed, as the statement says “Type 1 diabetes has a sufficiently characteristic clinical onset,” meaning that the symptoms are usually sufficient to identify it, with blood levels serving as confirmation, but “type 2 diabetes has a more gradual onset, with slowly rising glucose levels over time, and its diagnosis has required specified glucose values to distinguish pathologic glucose concentrations from the distribution of glucose concentrations in the nondiabetic population.” In other words, there has been a need for measuring blood glucose levels, not only reported symptoms, to diagnose it. The problem comes in because the tests used to diagnose diabetes are “snapshots” — they are a point in time measurement that don’t show if glucose levels have been elevated for a length of time.
A quick run-down of the tests used usually used to diagnose diabetes:
Fasting plasma glucose – a test of blood drawn from a vein after an overnight fast. A value over 125 mg/dl has been considered sufficient for a diagnosis of diabetes. Values in the range of 100-125 mg/dl are considered prediabetes.
Casual plasma glucose – a test of blood drawn from a vein at any time. A value of 200 mg/dl or higher is considered diagnostic of diabetes.
Oral Glucose Tolerance Test – a test of blood drawn before and after consuming a beverage containing 75-grams of glucose. A value of higher than 200 mg/dl at a point in the test is considered diabetes, and a value of between 140 mg/dl and 200 is considered prediabetes. (This test is the one most often used in pregnancy to detect and diagnose gestational diabetes. It’s also regarded by most people as a highly unpleasant test.)
I’ll mention here that home monitoring of blood sugar isn’t diagnostic — but it is used to monitor and measure blood sugar, and to see what the impact is of food, activity and medications on blood sugar levels.
Until now, A1C wasn’t considered a diagnostic test, as there were concerns that the cutoff values weren’t know or correlated with what diabetes is.
The A1C test, rather than measuring blood glucose at one point in time, measures the amount of glucose that has “gotten stuck” to the hemoglobin in a person’s blood, and it measures blood sugar levels over the past 2-3 months (as long as the red blood cells live). It doesn’t require fasting to be accurate. An A1C in the 4-6% range is considered normal. An A1C of 6% corresponds to an average blood glucose of 126 mg/dl, and an A1C of 7% corresponds to an average blood glucose of 154 mg/dl. Usually, people with diabetes are encouraged to have an A1C level of less than 7% (or less than 6.5% in some cases). The highest A1C I’ve ever had has been over 9% (corresponding to an average blood glucose of more than 200 mg/dl), but in recent years, it’s been consistently around 6% (lower when I was pregnant — which can be in part due to the higher blood volume during pregnancy).
You can use this application to convert an A1C value into an estimated average glucose number, if you are curious.
So, back to diagnosing diabetes… it sounds like A1C would be a better way to go, doesn’t it? But consider for a moment what type 2 diabetes is. The idea behind identifying people who have it is to prevent the damage that unmitigated high blood sugar does to the body — the large and small blood vessels, in particular. Diabetes complications are epic and scary, but they come down to damage caused by the body’s insulin not doing what it does in people who don’t have diabetes, or a lack of insulin altogether. There are other metabolic irregularities at play, having to do not only with blood sugar, but blood fats, too, that play a role. The experts who released this statement compared the other tests with A1C to see which were best able to predict diabetes complications. A1C did just as well as the other tests when they looked at three different populations. In particular, “the prevalence of retinopathy increases substantially at A1C values between 6.0 and 7.0%”.
So, what do you need to know right now?
- This is not yet the norm, it’s being talked about.
- A1C is a test that can be done at any time, not only fasting, and it appears to be at least as good as other methods for diagnosing diabetes.
- Some people may not be able to use an A1C test, or may need a special type of A1C test (“there are patient conditions that either will require a specific A1C assay method or will preclude A1C testing”).
- An A1C of 6.5% or higher (corresponding to an estimated average blood glucose of 140 mg/dl) is what is being recommended for the diagnostic cutoff for diabetes, type 2 in particular.
Next, I’ll write about what this means in terms of prediabetes (maybe it will go away as a term), what this may mean for diabetes treatment, especially for those with newly diagnosed diabetes.
Any questions? Comments? Were you bored? Riveted? On the edge of your seat? Infuriated? Feedback is appreciated!
Oooo… neat post! As I know very little about diabetes, my only comment at this time is that I am looking forward to your pre-diabetic post. In the past, some docs have tried to pin this diagnosis on me… however, this was always during times when I was binging a lot (and perhaps purging as well via exercise), so my sugar levels of course were way out of whack. Back in those days, I’d try to use the pre-diabetes bit to scare and hate myself into finally getting thin… of course, that caused more binges and so on. Sigh…
Nowadays, I have no symptoms of pre-diabetes and docs no longer give me the label… I think pre-diabetes and diabetes are facinating subjects, because they affect so many of us.
Thanks so much. I also look forward to reading your next installment. I worry about my blood sugar too. I have been doing IE for almost 4 years and I still eat large amounts of sugar almost daily. Before IE I restricted sugar intake quite a bit. I cannot tell if my cravings are hormonal/blood sugar related or that I have not fully give myself permission to eat it. I really don’t know.
My sugar intake worries me but I just don’t want to return to restricting. It seems like I prefer less nutritious foods. I thought I was supposed to return to eating a wide array of foods that satisfy my body and my need to eat. I wonder if after so long that it will ever happen.
I was diagnosed with type 2 diabetes almost 4 years ago. It took over 3 years for me to convince the endocrinologist that the A1C test wasn’t accurate for me. I would show him my records of morning and after-meal glucose tests, and show how I should have an A1C of over 7, given my glucometer readings. But my A1C was never over 4.6.
For whatever reason, my A1C never budged from a range of 4.4 to 4.6, even though my morning blood sugars would be anywhere between 130 and 170, and they would be in the high 200s after meals. I was starting to get diabetes symptoms (having to pee a lot, tingling in my feet, irritability), but the endo was reluctant to do anything because he kept saying the A1C was fine.
Finally, after showing him my records of a month of morning blood sugars over 150, he did some different blood test, looking at my hemoglobin. He said the results showed that I have anomalous hemoglobin, and that it explained why my A1C results would be wrong for me.
I don’t know how common this is, but my endo was making bad decisions about how much treatment I needed based on the A1C, and ignoring my glucometer results. I felt he really dismissed me and it took years to get him to listen. So it worries me to hear that A1C might become the standard for diagnosis. Like I said, I don’t know how common it is to have funny hemoglobin, but it just worries me when doctors rely too much on any one number or test, and ignore what their patients are telling them.
HairyLegs, I’m so sorry your Endo wasn’t paying closer attention to your blood sugar logs. Your comment makes me really glad that I included that caveat about the tests. I don’t know how common atypical hemoglobin is, but it isn’t completely uncommon, so your endo should have been paying closer attention. Also, not all endos wait until A1C is high to act. Most people would have seen that an A1C of 4.6 wouldn’t match up with fasting blood sugars of 130s unless you were experiencing lots of lows, too.
I’m also sorry your blood sugar ran high during that time.
So, what do you use now to measure your longer-range control? Do you feel like you can tell by how you feel?
You may want to contact the authors in the article I linked to with your story — they may not realize this could be a widespread consequence and that they need to propose a protocol for determining anomalous hemoglobin (A1C low, with diabetes symptoms). I don’t think the fasting blood sugar test is going to go away, if people are fasting anyway for blood lipids tests, providers are probably going to continue to order it. I would worry about people in your situation who would go undiagnosed (or misdiagnosed) for a long time.
Thank you so much for telling your story here.
“So, what do you use now to measure your longer-range control? Do you feel like you can tell by how you feel?”
Wow, this is a really good question. Since the endo finally stopped using the A1C, we’ve just looked at my logs of morning blood sugars, and he ordered fasting fructosamine test for the next visit. But I think the fructosamine only reflects the last 1-3 weeks. So I guess I don’t really have a plan to measure long-range control. Hmm…
One of the frustrations I’ve had with my endo is that he is primarily focused on my weight, and seems only secondarily focused on my blood sugar levels. He has mentioned the research that shows that very tight blood sugar control doesn’t provide much benefit, so he isn’t aiming for super tight control. But I don’t have a sense of what my blood sugar numbers would have to look like before he would try more medications or insulin. His almost total focus on my weight makes me very, very angry with him. I need to talk to my insurance about seeing if I can change doctors, I think.
Thank you for your reply to my question. I was wondering if a fructosamine test would be indicated.
I don’t know if it’s necessary to have an every-three-months type picture of blood sugar control. Maybe multiple systems.
If you can change doctors, it sounds like it would be a good idea — anger isn’t really helpful.
I take the maximum amount of metformin, and right now, long-acting insulin once a day, and this provides me with really good control — my fasting blood sugars are where I like them to be, and I don’t have any hypoglycemia.
There’s some research to support the idea of tight control being not totally helpful, but it really depends on the person and their goals. When it comes to preventing complications, an average blood glucose of 130 or less (about the same as an A1C of 6.5) seems to be the range to aim for.
One thing that you might see if your insurance company would pay for would be continuous glucose monitoring. If you aren’t able to change doctors, and you log your activity, food and blood glucose levels, your doctor might see what is happening in a more “objective” light.
I wish you could see my endo — he appears to be overall very “fat friendly” — we only talk about weight when I bring it up.
I’ve been thinking lately about what my longer-term goals are, and I think it’s not totally unreasonable that I would need to manage my diabetes for another 30-40 years (I’m 40 now), so I’m trying to figure out what is in my best interest, overall. What it comes down to for me is, I’m not afraid to take insulin, I’m not afraid to add medications, if needed, but I want to be as active I can for as long as I can.
Some internal medicine doctors are just as good or better than some endocrinologists at managing diabetes, you don’t have to see an endocrinologist.
[…] 23, 2009 by wellroundedtype2 In part 1, I talked about the potential switch to the A1C test for the diagnosis of diabetes, in particular, […]
I feel far more men and women will need to read this, really great info.