As continuous glucose monitoring (CGM) becomes the new standard of care for type 1 diabetes patients, experts are focusing more on “time in (target) range” as a tool for measuring diabetes control. For most people a CGM improves the time people with diabetes spend in the target range. Target range is usually defined as between 70 - 180 mg/dL. The goal is to spend less time below 70 mg/dL or above 180 mg/dL.

Different versions of the Ambulatory Glucose Profile (AGP) are available from our meters, CGMs and insulin pumps. These reports may have the target range and show the shows the percentage of time spent in target range and time spent above and below target range.

You don’t need to be on CGM to focus on improving your time in range. People who are using blood glucose meters can see the distribution of their blood glucose readings, but not everyone on insulin needs a CGM.

AGP also give an average glucose and some measures of how much you are cycling from high to low and back again. And many of the reports show this as a cloud-like graph to help you spot the times of your day where you tend to be high or low. It can also and show the individual day to day ranges that can reveal days that might be learning experiences or worth celebrating!

The A1c is still the best validated tool for predicting outcomes. The however it can also be skewed by wide swings with periods of time in dangerously low glucose levels and can mask the existence of high glucose spikes that may be contributing to the risk of complications.


Looking at the individual days above, the wider glucose swings on the 17th and moderate variations on the 22nd can produce similar A1c reports although the person with the mild ups and downs in the target time in range will feel much better. This why time in range can more useful than A1c in determining day to day diabetes control.

Tips from Mary Rose Deraco RN, BSN, Certified Diabetes Educator at USC Westside Center for Diabetes, for improving your time in range:

·   Ask your diabetes practitioner for your personal target glucose range. The lowest premeal target and the highest post meal number are used to set your glucose range. Most CGM reports come with a preset range target of 70-180 but your doctor might adjust your range depending on your age and other health conditions. It is normal to hit the top number of your range up to 2 hours after eating and to return to the mid to lower levels of your range in between meals and overnight. If you are not on CGM test your 2-hour post meal glucose levels to get a better picture of your highest glucose levels after meals.

·   Stay in range as often as you can without causing additional low blood sugars. Make slow and gradual improvements such as increasing your time in range by 10% over a 1 to 2-week period of time.

·   Match your insulin peak to your carbohydrate glucose rise. Time your bolus 15-20 min prior to eating. Most rapid acting insulins work at their greatest intensity peak 60-90 min after injecting. Carbohydrates peak as sugar in the blood 15-90 minutes after eating them.

·   Know how foods effect your glucose. When you combine high fiber complex carbohydrates with vegetables, protein and fat, the glucose peak matches up better with the insulin peak for improved post meal blood sugar control. Accurate carbohydrate counting is key to keeping glucose levels in range. There are great mobile apps such as MyFitnessPal and Calorie King or use Siri to look up your carbs before dosing. Make an appointment to see the diabetes educator if you feel you need carb ratios adjusted or a review of carb counting.

·   If blousing 15-20 minutes before eating is a challenge for you, ask your practitioner if you are a candidate for Fiasp or Afrezza which are faster acting insulins that launched this year.

·   If you see up arrows 30-90 min after a meal, it is normal. If you went beyond your target range, it is most likely that your food reached the blood stream quicker than the insulin peak or you didn’t get enough insulin to match your intake. Try not to stack multiple insulin doses top of each other, it can cause hypoglycemia and knock you out of range. Ask your healthcare team when and how to safely correct highs.

·   Look at your CGM 10-20 times per day. Before meals, 2 hours after meals, when you have symptoms, before driving and during times of increased activity or stress. Make observations at first and try to change behaviors like walking after meals, administering insulin earlier and choosing more complex carbohydrates instead of changing insulin doses.

·   Learn how to use trend arrows, temporary basal rates and correction dosing. Your diabetes team will give you individualized instruction for using trend arrows.

·   Learn how to read you CGM reports. The time is range value is found in the AGP report. You can’t manage data that you don’t see, so be sure to learn how to read your data. Seeing improvements will really motivate you to focus a little bit more time on diabetes management and achieve much more “time in range”.

If you feel you need more instruction on “time in range”, CGM or advanced insulin management, Mary Rose is available for individual diabetes instruction at USC Westside Center for Diabetes contact her at for an appointment

Mark also recorded a video of Richard Berganstal, MD, one of the creators of the AGP report at the 79th ADA Scientific Sessions. Watch our Facebook page and Twitter stream for a link to the video on Medscape to hear his tips as well.