Disclaimer: The following guide is my best guess on what content will be on the exam. I do not know what exactly will be on the exam but I have helped over a thousand health care professionals pass the exam.

Please note there is a 2021 update to this chapter that can be found at the end of the Study Guide. If there is a conflict of information in the literature, the update supersedes previous guidelines. You want to memorize the figures and tables in the update instead of the ones in this chapter. However, there is information in this chapter that is not in the update (such as factors that affect A1c) so you should still review this chapter. The importance of this chapter is now medium.

Chapter 9- Monitoring Glycemic Control
Importance: Now Medium- Read at least twice
Approximate time recommended: 45 min

I have highlighted what I think will be important for the exam. However you should read the entire chapter. All areas in grey (key messages and recommendations) are also important for the exam.

Under the heading of: A1c Testing

I want to explain how Table 1 works in the hopes that you will need to memorize less if you can understand the mechanisms behind altered A1cs. Hemoglycated A1c is a form of hemoglobin that can be found in red blood cells that is chemically linked to glucose. Glucose from the blood slowly binds to the hemoglobin over the life of the red blood cell (3-4 months) in a process called glycoslation. The higher the amount of glucose in the blood the faster this occurs leading to more hemoglycated A1c in people with higher sugars. Even in people without diabetes this is occurring because people without diabetes still has glucose in their blood binding to the hemoglobin in their red blood cells. That is why a normal A1c is 4-6% (0.04-0.06). However in people with diabetes their sugars are higher which glycosylates faster leading to more glycated hemoglobin which shows up as a higher A1c. I explain it to my patients like so: pretend that the red blood cells are like 90 day old doughnuts and as they swim in your blood the more sugar there is in the blood the more of a glaze there is on the doughnut. Your A1c is the thickness of the glaze on that doughnut.

So what can falsely lower the glaze? Let’s say a patient gets into a car accident and loses a lot of blood and requires a transfusion. If they go for an A1c in a few weeks well those new doughnuts haven’t collected their 90 day glaze leading to a falsely decreased A1c. Same if they have a hemoglobinopathy (like sickle cell anemia) that destroys the doughnut after a few weeks.

So what can falsely increase the glaze? Let’s say a patient has anemia and can’t create new doughnuts forcing the body to use the old ones for longer. That means the doughnuts swim for longer collecting more glaze resulting a a falsely elevated A1c. Same thing if there is chronic renal failure and the  kidneys cannot secrete adequate erythropoiesis to stimulate new red blood cells.

For some more details on why certain factors affect A1c please see table 2 of the following study- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3912281/

Under the heading of: Self Monitoring of Blood Glucose (SMBG)

The recommendations for individualized SMBG can be found in Appendix 5. However with the 2021 SMBG update there are newer recommendations so you should be familiar with the updated recommendations.

 

Practice Questions (press show answer to reveal answer)

Which of the following statements are all true?

A) Hemoglobin A1c can be used to diagnose diabetes, represents the mean plasma glucose of the past 12-16 weeks and can be affected by disruptions to white blood cell turnover
B) Hemoglobin A1c should not be used to diagnose diabetes, represents the mean plasma glucose of the past 8-12 weeks and can be affected by disruptions to red blood cell turnover
C) Hemoglobin A1c can be used to diagnose diabetes, represents the mean plasma glucose of the past 8-12 weeks and can be affected by disruptions to red blood cell turnover
D) Hemoglobin A1c should not used to diagnose diabetes, represents the mean plasma glucose of the past 6-8 weeks and can be affected by disruptions to white blood cell turnover

You have a patient with type 1 diabetes who hates testing his sugars. He is currently taking Tresiba (degludec) once daily and Apidra (glulisine) three times daily. He has not had any episodes of hypoglycemia for many years. His A1c is currently at target at 6.8% (0.068) What is the minimum amount of SMBG he should be doing daily?

A) Once daily as he is on target
B) Twice daily as he has not had any episodes of hypoglycemia for a long time
C) Three times daily as he is on rapid acting insulin
D) Four times daily as he takes insulin four times a day

To get samples of the Libre sensor for either yourself of your patients either you or your patients can attend a webinar and get a free sensor.