What are Normal Blood Sugars? What are Antibody Tests?
Recently somebody ask the following 2 great questions: Please tell me what the numbers are for normal BS levels in your country. In Canada we use a different scale and would like to compare the two. I am also curious to know about the antibody tests that seem to be standard practice down there and not in Canada.
Blood Sugar Levels
What constitutes normal blood sugars in not as cut and dry as it may seem. There are disagreements between the various institutions as to how to define normal blood glucose levels. Of course there are politics involved in determining some of these numbers. Factors such as age and genetics can also affect normal ranges.
With that said, I think the chart below is one of the better charts for showing the range of blood glucose levels from normal to established diabetes.
This chart is in the U.S. unit of measure, which is mg/dL, and the blood glucose values are for plasma blood glucose. There is an easy to use Blood Sugar Convertor that helps you to get your blood sugar conversion results either in mg/dL (U.S. system) or in mmol/L (European system).
Glucose vs. Plasma Glucose
Glucose levels in plasma (one of the components of blood) are generally 10%–15% higher than glucose measurements in whole blood (and even more after eating). Glucose is dissolved in water. The plasma phase of blood has a higher concentration of water (~93%) compared to that of red blood cells (~71%). Therefore plasma has a higher glucose concentration than that of whole blood.
This is important to know because home blood glucose meters measure the glucose in whole blood while most lab tests measure the glucose in plasma (may also be called serum glucose). Currently, there are many meters on the market that give results as "plasma equivalent," even though they are measuring whole blood glucose. The plasma equivalent is calculated from the whole blood glucose reading using an equation built into the glucose meter. This allows you easily to compare your glucose measurements in a lab test and at home. It is important for you (and your health care provider) to know whether your meter gives its results as "whole blood equivalent" or "plasma equivalent."
Click here for a great resource that demonstrates how these two numbers map to each other by inputting your latest A1c.
The next chart shows how the American Diabetes Association (ADA) determines a diagnosis for diabetes, and it contains both the U.S. unit of measure and the European unit of measure:
You will notice they have a footnote that says A1c does not apply to diagnosis of type 1 diabetes. That is because type 1 diabetes is typically diagnosed in the hospital with high blood glucose levels that have come on quite rapidly. This makes using an A1c to diagnose it unnecessary, but it still may provide valuable information.
Speaking of A1c, A hemoglobin A1C test is primarily used to measure average glucose over prolonged periods of time. The test measures the buildup of glycated hemoglobin (a type of advanced glycation end product, or AGE) within the red blood cells. This measurement reflects the average level of glucose the cell has been exposed during its life cycle which is approximately 10-12 weeks.
There are many conversion tables available, and most of them do not agree. I know of at least three formulas for converting from an A1c to an average blood sugar level or vice versa. The chart below is based on the conversion formula of Dr. Richard Bernstein. In my opinion this is the most accurate conversion correlation chart.
According to Dr. Richard Bernstein a normal, healthy, thin, non-diabetic A1C will be within the range of 4.2-4.6. He also believes every diabetic can and should target, attain and sustain these normal levels.
The American Diabetes Association (ADA) states an A1C of less than 6.0 is normal and recommends an A1C less than 7.0 in diabetics.
The American College of Endocrinology (ACE) and the American Association of Clinical Endocrinologists (AACE) adopted a target A1C of less than 6.5 percent at their diabetes treatment consensus conference in 2001.
Although the diabetes experts disagree on the definition of a normal A1C and a target A1C for diabetics, they do agree that lowering A1C has been associated with a reduction in microvascular and neuropathic complications of diabetes and possibly macrovascular disease.
The ADA states "More stringent goals (i.e., a normal A1C less than 6 percent) should be considered in individual patients based on epidemiological analyses suggesting that there is no lower limit of A1C at which further lowering does not reduce the risk of complications…(particularly in those with type 1 diabetes)."
We believe targeting an A1c below 5.6 is best, because that is supposedly the threshold above which microvascular and macrovascular disease is most likely to occur.
Most people who develop type 1 diabetes have immune markers in their blood such as antibodies against insulin, islets, or the enzymes glutamic acid decarboxylase (GAD) and IA2 (also known as ICA512). By measuring these markers and conducting metabolic tests, scientists can now gauge the risk for developing type 1 diabetes in relatives of people with the disease. Tests include:
People who are treated with insulin injections may begin to develop antibodies directed against the exogenous insulin. The IAA test does not distinguish between these types of antibodies and the autoantibodies directed against endogenous insulin. Therefore, this test is not valid for someone who has already been treated with injections of insulin. For example, someone who was thought to be a type 2 diabetic and who was treated with insulin injections cannot then have this test done to determine if they are actually a type 1 diabetic.
The autoantibodies seen in children are often different than those seen in adults. IAA is usually the first marker to appear in young children. As the disease evolves, this may disappear and ICA, GADA and IA-2A become more important. IA-2A is less commonly positive at the onset of type 1 diabetes than either GADA or ICA. Whereas about 50% of children with new-onset type 1 diabetes will be IAA positive, IAA positivity is not common in adults.
Not everyone with autoantibodies progress to diabetes type 1, but the risk increases with the number of antibody types, with three to four antibody types giving a risk of progressing to diabetes type 1 of 60%-100%.
If ICA, GADA, and/or IA-2A are present in a person with symptoms of diabetes, the diagnosis of type 1 diabetes is confirmed. Likewise, if IAA is present in a child with diabetes who is not insulin-treated, type 1 diabetes is the cause.
If no diabetes-related autoantibodies are present, then it is less likely that the diabetes is type 1. Some people who have type 1 diabetes will never develop detectable amounts of islet autoantibodies, but this is rare. The majority of people, 85% or more, with new-onset type 1 diabetes will have at least one islet autoantibody.