The A1C test is a blood test used to measure the average level of glucose in the blood over the last two to three months, and is used as a means of checking how well blood sugar levels are being controlled for a person with diabetes.ore detail and supporting information is in the body of this article. 1  A1C is an abbreviation for glycated hemoglobin, which forms when glucose attaches to a protein in red blood cells. 2  As blood glucose levels rise, so does the percentage of glycated hemoglobin, so A1C is used to measure diabetes control.
Note: To see if multiple ratios are proportional, you could write them as fractions, reduce them, and compare them. If the reduced fractions are all the same, then you have proportional ratios.
The above features are not supported. If either side of the proportion has a numerator and denominator that share a common factor with a variable, the calculator will report an erroneous solution. Example: 1/2 = x/x will cause the calculator to report 0 as a solution, even though there is no solution.