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How to interpret your glucose reports: highlights from a Masterclass

Earlier this year, we were lucky enough to sit down with endocrinologist Prof. David Segal for a Masterclass on how to interpret your glucose reports. It was fascinating! Here’s what we learnt…

What are glucose reports?

First of all, let’s look at what exactly we mean when we say glucose reports. They’re the detailed reports you get from your FreeStyle Libre or CGM, that give a picture of what your blood glucose has been doing. You can set a time frame for them, and there are various aspects within the reports to focus on: time in range, glucose variability, hypo events, etc. Prof. Segal gave us so much to think about, but there were a few key points that we wanted to highlight.

glucose report

Glucose variability

Glucose variability – also called the ‘coefficient of variation’ is an important number to look at. High variability means you’re having lots of highs and lows, and not a lot of steady blood glucose in between. High variability is not good, both for your health and for your quality of life – we all know how awful it feels to have a rollercoaster day! Prof. Segal said to aim for below 30% glucose variability if possible.

Set a target

It’s so important to have a target goal to work towards. A target range of of 4mmol/l to 10mmol/l is realistic, says Prof. Segal, and then you can work towards a percentage time in range that feels achievable to you. The recommended time in range is 70%.

Your time in range goal is a personal matter: it depends on your age, health, diet, medication, and risk of hypoglycemia (low blood glucose). There are general guidelines though:

  • 70% of the day in target: 3.9mmol/l to 10mmol/l
  • Less than 4% of the day below 3.9mmol/l
  • Minimise the time spent above 10mmol/l

Insulin timing and dose

Because we were specifically talking about Type 1 diabetes, we were also able to discuss insulin. Prof. Segal said that the very best insulin works differently every day by 30% – whether it’s short- or long-acting. A 30% difference day to day! Other insulins can be up to 50% difference. So it’s inevitable that your blood glucose results will vary from one day to the next.

When it comes to insulin injection timing, it’s a good idea to inject 30 minutes before a meal, if you are higher than you’d like to be. If you’re in your target range, it can be 15 minutes before.

Remember: the bigger the dose, the longer it lasts. Whether it is  short- or long-acting insulin. So if you’re taking a big dose of insulin to cover a high carb meal, it’s going to be active in your body for a longer time.

agp ambulatory glucose profile

Reading the Ambulatory Glucose Profile

When you’re looking at your Ambulatory Glucose Profile (AGP), it’s important to recognise that the dark blue line is your average over the period you’re looking at (1 day, 1 week, 2 weeks, 1 month, 3 months etc).

If you want to fix the slope of a curve (a recurring spike at a certain time of day, for example), you don’t change the dose to fix the curve. If you get back to where you started (a similar blood glucose reading) 4 hours later, that means your dosage was right. You change the curve by changing the timing of your insulin dose.

Food choices

Food choices also obviously play a huge role in blood glucose control – and can be seen in your glucose reports. Did you know that white bread has a higher GI than table sugar?! (Here’s what GI is, if you need a reminder.)

Prof. Segal said that if you eat more than 60g of carbs in one meal (that’s 4 x 15g carb portions), it is not possible to get a normal blood glucose reading. 4 servings of carbs at one time is too much. Here’s how to carb count, so that you know what that looks like.

how to eat pizza with type 1 diabetes

We also talked about the Pizza Conundrum, and how it’s virtually impossible for people with Type 1 diabetes to eat pizza without having crazy blood sugar afterwards. Prof. Segal explained that it’s because you can’t burn two fuel sources at the same time. So a high carb high fat meal (like pizza) doesn’t work. The body won’t metabolise carbs while burning fat at the same time. The fat will hang on for longer and cause insulin resistance and it will need a higher insulin intake.

His tips? Eat the protein part of your meal first, before your carbs – that will give you better blood glucose than starting with the carbs. (Here’s a reminder of the different food groups, if you need it!)

He also said that if you have one glass of wine  before supper (or other alcohol without sugary mixes), that will result in better blood glucose because alcohol slows down the amount of sugar coming out of your liver. If you’d rather not drink alcohol, then adding some vinegar to your food has a similar result.

Life hacks for living with diabetes

Finally, we discussed some of Prof. Segal’s most helpful life hacks for living with diabetes.

Routine is key to controlling diabetes.

Prof. David Segal

The importance of routine came through loud and clear. He suggested that, ideally, you want to have:

  1. A low carb breakfast because you are most insulin resistant in the mornings.
  2. A more interesting lunch, because you’re more insulin sensitive at this time, and have the afternoon to make any necessary adjustments if you calculated wrong.
  3. A good supper so that your blood glucose remains constant while you sleep.

Prof. Segal’s last word of advice when it comes to glucose reports? Understanding your day graph is better than having a perfect HbA1c. Knowledge is power!

You can watch the full recording of the Masterclass here.

Photo by Ivan Torres on Unsplash

What to read next?

7 day low carb meal plans: If you want to eat low carb, these are exactly the meal plans you’re looking for.

Everything you need to know about the FreeStyle Libre: We gathered all your questions and answered them – here’s all you need to know about the Libre.

What is a CGM? Flash glucose monitoring and CGM: Not sure what the difference is, or what these words mean? Read this article.

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Sweet Life is a registered NPO/PBO (220-984) with a single goal: to improve diabetes in South Africa. We are funded by sponsorships and donations from aligned companies and organisations who believe in our work. We only share information that we believe benefits our community. While some of this information is linked to specific brands, it is not an official endorsement of that brand. We believe in empowering people with diabetes to make the best decisions they can, to live a healthy, happy life with diabetes.