Hemoglobin A1c may become a valuable test for identifying diabetic patients. Luckily, there is a Hemoglobin A1c test that is available for home use from some pharmacies and online home health screening companies so it is available for all.

The trouble with the A1c test is that there is great confusion in interpreting its value. There is strong evidence that diabetic complications result if the post-meal glucose level exceeds 140 mg/dl. If peak blood glucose is kept below 140 mg/dl, the average value must be appreciably less, certainly no greater than 120 mg/dl. A 3-month average blood glucose of 120 mg/dl corresponds to an A1c value of 5.6%. Hence I conclude that A1c must be kept below 5.6% to avoid diabetic complications.

Nevertheless, the American Diabetes Association recommends 7.0% as a healthy A1c goal, and the American Assoociation of Clinical Endocrinoloogists recommends an A1c goal of 6.5%. How do we reconcioe these apparently lax goals with the 5.6% A1c limit given above?

The A1C is a good test but how reliable is it when a glucose tolerance test is normal for someone who has a higher A1C. Is that person diabetic or is there some other reason where the A1C is higher than normal?

Great point seashore! In the work we do via the healthy babies program at mygluco.com with diabetes in pregnancy, the cut off for referral is actually 5.7% since that's where complications begin including neural tube defects, fetal demise and premature birth.
Kevin McMahon - Diabetech

Seashore, I know the topic of this article is to help diagnose type 2 diabetes in the general public and I agree that A1C interpretation varies, but please remember that there are type 1s also reading these articles. To say that 6.5 or 7.0 A1C goals are "lax" is insulting to type 1s like me. Because we are dependent on injecting our own insulin, we are subject to the lows that occur with tight control. Of course, lower than the ADA recommendation is better, but I do not know of a fellow type 1 anywhere near "your" recommended A1C of 5.6 who doesn't frequently end up in the hospital because they slip too low (and have subsequently lost the ability to sense a low coming because of their consistent low readings). It is a very fine line to manage, and hard for anyone else (type 2 or nondiabetic) to understand. Get educated, differentiate type 2 from type 1 when making a strong point and don't condescend.

A1c can help identify people, but it can't rule people out. You can have a great a1c and have large swings in blood sugar that are just as harmful. It also doesn't take into account hemoglobinopathies or anemia.

As to how to reconcile one's target A1c with the official recommendations...I personally don't try. DM1 is a condition requiring self-management (and self-monitoring, including that of the A1c values), and therefore it is (in my opinion) up to me as a person with DM1 to take the facts, understand them, educate myself, and finally arrive at a treatment goal that makes sense in terms of my BG control and ability to avoid diabetic complications (both those of hyperglycemia and those of hypoglycemia).

In other words, the person without DM1 is unlikely to have diabetic complications (retinopathy, neuropathy, nephropathy, cardiopathy) probably precisely BECAUSE they are unlikely to have A1c's of more than around 5%. Hence, that is my (in my mind) a rational) personal, individual goal.

I have patients with DM1 who prefer to maintain their A1c around 4.8%, and they are able to do so, WITHOUT ever having ended up in the hospital because of severe hypoglycemia. In contrast to what "Anonymous" above writes, I find it insulting to a person with DM1 or DM2 especially to say, "Hey, settle for 6.5% or 7% A1c because that is all that you can safely achieve." The matter resides in information, knowledge, and a lowered CHO meal plan with associated lowered doses of basal and prandial insulins. Maybe such control was nearly impossible in the 1940's or 1960's or 1980's, before the new insulin analogues and the home BG monitors were available...but today, such control is indeed possible and, if the published information on diabetic complications is believable, recommendable.

At over 60 years of age, I have had DM1 for over 40 years and have always used insulins. Of course I have had hyperglycemia AND hypoglycemia (18 mg/dL once while using Regular insulin and Ultralente). However, never have I been hospitalized (or even unconscious) from severe hypoglycemia...mainly, in my opinion, because I practice what I (and Bernstein and many others) preach. The role of genetics is still undefined but perhaps some people are better protected genetically from the hospitalizable effects of low BG. But, in the vast majority of my experience and practice, the individual's treatment and control of BG contributes the major part in the long- or short-term complications of DM and its treatment.

Being hospitalized for severe hypoglycemia is a short-term complication of DM insulin treatment, to be sure. Both short- and long-term complications can be a pain in the **s and are worth learning to avoid.

As far as the usefulness of A1c in diagnosis of DM2 or DM1, I think it is useful in pointing to a metabolic abnormality or dysfunction. An A1c result of above 5% (more or less) indicates that all is not well with the endocrine system and metabolic control. After finding such a result, it is up to the physician, Certified Diabetes Educator, and person affected to figure out (that is, to rule out) the possible but not real causes of the aberration. Even with the FBG (fasting blood glucose) value, one has to be careful because it can be affected by various factors. It is the TOTAL clinical picture that is useful in diagnosis, not just a single serum blood value, whether A1c or FBG.

cde, You quoted me as saying "Hey, settle for 6.5% or 7% A1c because that is all that you can safely achieve." That is not what I said, nor what I implied in my previous post. Please be careful in the future when quoting someone. In fact, what I said was "of course, lower than the ADA recommendation is better ..." I think everybody knows that. It is just a slipperly slope for type 1s.
The point of my post was that it is misleading when people lump type 1s and type 2s under the same diabetic umbrella when making statements. Although my A1Cs are below the ADA recommended and I have not landed in the hospital either, many type 1s have a very hard time acheiving these goals to begin with. And to refer to them as "lax" was offensive to me (and probably discouraging to those who struggle to reach them). Staying below a 5.6 A1C is an aggressive goal FOR A TYPE 1 and not without risk. My point was simply to differentiate that.
I am on CGM and have talked to many type 1s trying to acheive A1Cs in the mid to low 5s who have repeatedly ended up in the hospital. That type of "short-term complication" sounds like scary stuff to me (as I know it is for their families who make the 911 call to get them there).
Diabetes, both type 1 and type 2, is complicated at best and hard to categorize in sweeping, general statements. I think it ends up being quite individual (given other personal hormonal, genetic, health factors ...), and each one of us should strive to do our personal best given the hands we are dealt.
My best wishes for your continued good health.

This is just a couple of comments on cde's comments. I am 61 years old and have had very labile dm1 for over 55 years. I had many occasions of unconsciousness and hospital visits for insulin shock. Now I do an average of 15 blood glucoses a day and am very happy with A1c's in the 6's. If I tried for 4.8 I think I would be in real trouble. I think that even within the volatile dm1's there are many variations in individual tolerance and individual degree of volatility. Perhaps genetics do play a part.

In regard to Anonomymous' comment on Type 1 and Type 2, I couldn't agree more. They're like apples and oranges. Most health news segments on TV, don't differentiate between the two sufficiently when presenting a new drug or other report
on "diabetes". Years ago, they should have been given different names because they are 2 very different diseases with a few similar symptoms.

From a Florida MD:
CDE says most of it. It needs to emphasized that it is the WHOLE PICTURE not just one test that is important.
The A1c is far from a perfect test. Hemoglobinopathies, transfusions, patients using erythtropteitin stimulating factors, even patients with early type 1 DM could have "normal A1c" values and present in DKA. Unfortunately continued variability in the method all effect the test test.
Screening blood sugars are also severely flawed, a person with type 2 DM presenting with either a hepatic defect or muscular defect in sugar metabolism may have either abnormal fasting or only post prandial sugars.
Touching on control people with sugars with sugars between 110 and 130, 100 and 140, 90 and 150, 50 and 190 will all have the same A1c and it will be around 6.
THERE IS NO ONE TEST AND THE ENTIRE PATIENT / PERSON THEIR HISTORY, FAMILY HISTORY, SYMPTOMS AND FINALY TESTS NEED TO BE USED TO MAKE THE DIAGNOSIS. We need to re-evaulate the what we are treating, a relative or absolute deficiency in insulin, not a sugar number.
REMEMBER THE PATIENT.

Just a reminder to everyone:
The ADA does not state a hemoglobin A1c of 7% is the target goal, its official guidelines state "...the A1C goal for nonpregnant adults in general is

The WebMD magazine, Nov/Dec 2007, page 86 gives a figure that shows A1c guidelines, which designates 5 to 7 % A1c as “Target” goals, 8 to 10 % A1c as “Suboptimal” glucose control, and 10 to 12 % as “Poor” glucose control. These guidelines are dangerously lax, yet are apparently given to many diabetics.

Anonymous stated on 7 Aug that, “To say that 7.0 % A1c is lax is insulting to type I’s like me”. Blood glucose guidelines should be based on levels that cause diabetic complications, not on levels that are achieved by most diabetics. Of course it is much easier for a type II to achieve healthy blood glucose control than a type I diabetic, but the damage to the body produced by excessive blood glucose does not vary with diabetes type. All diabetics need honest blood glucose guidelines to protect their health.

A low-carb diet is essential for any diabetic (type I or II) to achieve healthy blood glucose control. The primary reason that many diabetics cannot achieve healthy blood glucose control is that they are following the misguided advice of diabetic authorities insisting that they eat a low-fat diet in order to minimize coronary heart disease. These authorities also insist that protein be limited, because diabetics often develop kidney disease, and a low-protein diet is commonly recommended for kidney disease patients. With these restrictions of dietary fat and protein, the diabetic is forced to eat a high-carb diet, and with such a diet he generally cannot properly control his blood glucose.

This dilemma can be remedied by recognizing that a low-fat diet and low blood cholesterol do not reduce heart disease. The claim that they do is a myth, which has been debunked in recent books by Gary Taubes, Malcolm Kendrick, Anthony Colpo, Duane Graveline, and Uffe Ravnskov. These books are readily available on Amazon.com. With a low-carb diet, the diabetic will not develop kidney disease, and so dietary protein need not be limited.

In short, a low-carb diet should be readily obtainable by all diabetics to achieve a healthy A1c value and a healthy heart.