Ask a DCES: How Do I Keep High and Low Numbers in Perspective?


Do you ever wish you could ask a diabetes care and education specialist (DCES) anything about type 2 diabetes?

In our new monthly Ask a DCES column, you can get your most burning questions answered from a DCES professional on various topics, including diet, medication, exercise and mental health. Want to submit a question to us? Email us at!

Dear DCES:  Sometimes I see high blood glucose numbers and at other times, low ones. It feels sporadic to me and I’m not sure how to evaluate them to learn what needs to be changed in my routine. How do I keep things in perspective when I see numbers that I am not expecting?

Dear Reader: We all know that measurements and numbers are a major part of managing diabetes.  But with all of that data, how do you figure out what to do with it and what it means?

Multiple factors affect blood sugar levels and not all are in your control. These make your numbers unpredictable at times. Your diabetes is unique and your body’s response to food, activity, medication, stress and other lifestyle factors is unique. But there are general guidelines based on research with thousands of people like you with type 2 diabetes that help put the numbers in context.  

When you put together what the guidelines recommend with your own experiments, you will begin to be able to make more sense of the numbers and know what to do with them.

Pro tip: Focus on overall trends and patterns and work on one problem area at a time.

What do the guidelines say?

The A1C test (also known as HbA1c or hemoglobinA1c) reflects your average blood sugar levels over the previous two to three months. National guidelines recommend most people should aim for an A1C between 6.5 percent and 7 percent, but also to customize it based on other factors. Having an A1C above 8 percent is considered a trigger for additional action or treatment.

The guidelines also recommend specific targets for blood sugar levels at different times of the day that correlate with the desired A1C targets above. 

  • Before meals: 80-130mg/dl 
  • Two hours after meals: <180mg/dl. 

Anything below 70 mg/dl is considered low (called hypoglycemia) and less than 54 mg/dl is considered very low. Both should be treated promptly with a simple source of sugar such as four glucose tablets you can buy at most drug stores.

More recently, due to the increased use of continuous glucose monitoring (CGM), guidelines recommend aiming for results from CGM devices to be in range (70-180 mg/dl) for at least 17 hours each day. If you use a CGM, you can leverage the increase in data and data analysis tools to focus on time in range rather than A1C. Since A1C is an average, it doesn’t tell you any specific information about high or low blood sugars you may have experienced.    

What is the Best Way for Me to Experiment? Bring Out Your Inner Detective

Time to put your detective hat on and get started. Think about your own diabetes management as a series of experiments, or actions you try that lead to learning. They are not a pass or fail exercise and do not have good or bad judgments associated with them. By experimenting, you learn more about YOUR diabetes and what gets you the results you want; that’s where the detective part comes in.

  • When experimenting, keep track of your notes in either a journal or an app on your phone to help you pinpoint patterns and trends. Although there are multiple things that could affect your blood sugar, the four main areas that you should include in your journal are activity level, food and beverage intake, medications and stress level. 
  • Pair your testing when trying to see the effects of a behavior. In other words, do a test before and after the behavior. Some examples of paired testing are:
    • Try a physical activity that you enjoy at the same time of day for a few days. Test your blood sugar before and at the same amount of time after the activity each day. The results for the days you experimented should reveal a pattern.  
    • Check your blood sugar before and two hours after you eat to see how different foods affect it. Try each food for a few days to see if there is a pattern.

Use available technology reports to help you identify patterns or trends. Many meters give information about highs and lows and offer software that reports out the data in a way to show where problem areas occur. CGMs offer sophisticated reports that compile all the data into actionable terms.

You are not alone when it comes to designing your experiments and comparing results to guidelines. A diabetes care and education specialist is trained to guide and support you in all your efforts. Click here to learn more

This content was created in partnership with the Association of Diabetes Care and Education Specialists (ADCES), a Founding Partner of Beyond Type 2. 


Jodi Lavin-Tompkins is a North Carolina native and a Master’s prepared nurse with over 30 years’ experience in diabetes care. She is currently the director of accreditation/content development at the Association of Diabetes Care & Education Specialists. Jodi’s career has spanned working in academic settings as a nurse practitioner to positions in the pharmaceutical and medical device industries, to managing a diabetes self-management education and support program in a large midwestern health system. She is passionate about making sure people with diabetes have the knowledge and skills they need to manage diabetes to best of their abilities. To Jodi, diabetes is personal; her mother, father, brother, niece, cousin, aunt and uncle all have diabetes.