8 – Activity Snacking to Increase Time in Range for T1D

Click here for Episode 8: Activity Snacking to Increase TIR for T1D

For a fun summary: 99 Problems But Highs Aint One (click if you want to download it, use it, share it!)

In this episode, John Pemberton explores how physical activity can supercharge insulin and significantly improve time in range. He explains the latest research, practical strategies, and how small movements throughout the day can help stabilise blood glucose levels. If you’ve ever struggled with post-meal spikes, found insulin corrections too slow, or wondered how to optimise your glucose control, this episode is for you.

At 02:14, John outlines the purpose of this episode, which serves as a preview of his upcoming ATTD presentation on the role of activity in improving time in range. He highlights that this topic is rarely discussed in standard diabetes education and aims to provide insights into how movement can help regulate glucose levels beyond simply using insulin.

At 04:28, John discusses the current exercise recommendations, which advise adults to do at least 30 minutes of moderate activity per day, with two additional strength-based sessions per week. For young people, the recommendation is an hour of daily activity with two to three intense sessions per week. However, he acknowledges the challenges of fitting this into modern life, where technology and convenience often encourage inactivity. He also addresses the common barriers to exercise, such as time, accessibility, and the fear of hypoglycaemia, particularly for people with type 1 diabetes.

At 06:37, John explains why insulin alone often isn’t enough to manage glucose levels effectively. He describes the issue of slow insulin absorption, explaining that, unlike in people without diabetes, injected insulin does not enter the portal vein, meaning that glucose is not efficiently stored in the liver. He also highlights how sitting for long periods reduces blood flow to the skin, slowing insulin absorption, and increases blood flow to the kidneys, leading to faster insulin clearance.

At 08:54, John introduces the concept of using activity to improve glucose control. He explains that movement increases blood flow to the skin, leading to faster insulin absorption, and directs more insulin to the muscles rather than the kidneys, making it more effective. Additionally, exercise promotes non-insulin mediated glucose uptake, meaning muscles can absorb glucose even without insulin.

At 11:12, John discusses key research studies that support activity snacking as a strategy for improving time in range. A 2012 study found that simply walking around for a few minutes every 30 minutes significantly reduced post-meal glucose levels in both people with and without diabetes.

Lauren Turner’s research demonstrated that walking 20 minutes before a meal could reduce post-meal glucose rises.

Matthew Campbell’s SIT-LESS study in the UK showed that just three minutes of movement every 30 minutes improved time in range by 14%.

At 13:35, John shifts focus to what people can do if they are already experiencing a high glucose level after eating. He explains that waiting for correction doses to take effect can be frustrating and often results in glucose rollercoasters. Instead, he introduces the “15 by 2” rule—15 minutes of movement can reduce glucose by approximately 2 mmol/L (40 mg/dL).

He shares seminal research by Professor Riddell (top bloke), Dr Zaharieva (absolute legend of a human being!), Dr Zoey Li (Awesome analyst) and colleagues’ analysis of 120 youth with T1D from four studies. A secondary and often overlooked analysis reported that 45-60 minutes of walking or cycling 2-4 hours after a meal with full insulin could bring glucose levels back to target without causing too much hypoglycaemia (<10%).

At 15:57, John expands on the “15 by 2” rule as a practical tool for daily diabetes management. If glucose is above 10 mmol/L (180 mg/dL), 15 minutes of movement can lower it by 2 mmol/L (40 mg/dL), while 30 minutes can bring it back to target. This approach provides a faster and more effective alternative to stacking correction doses and waiting hours for insulin to take effect. He states, taken a step further, activity after-meals can be used to optimise time in tight range (3.9-7.8 mmol/L or 70-140 mg/dL), by applying the below algorithm. However, there is a balance to be drawn, and this should dominate daily thoughts.

At 17:19, John discusses a large real-world studes called T1DEXI and DEXIP, which examined over 10,000 activity events in adults and adolescents with type 1 diabetes. This is when John “Semi-Stalked” Professor Mike Riddell, insisting on a secondary analysis for events with a starting glucose above 10.0 mmol/L (180 mg/dL).

After three months, Mike gave in and agreed!

The secondary analysis had over 1,900 events, over 1500 for adults and over 300 for adolescents.

The results confirmed that movement consistently lowers glucose levels, regardless of the type of exercise performed. Crucially, the study found that this strategy works only if insulin has been given within the past four hours—if there is no insulin on board, activity alone will not be effective. Dr Zoey Li’s analysis is, well, awesome!

But what about a matched pair analysis?

Say hello to Data Scientist Extraordinaire, Dr. Cat Russon, who is under the supervision of the legend, Professor Rob Andrews of EXTOD fame! This data was just shown at Diabetes UK 2025 and will soon be published. Well, it will if Cat and I stop fighting about the finer details of the analysis!

Tagline:

“20 minutes of activity = 20% drop in glucose”

The data confirms that 15 minutes of physical activity can lower glucose by ~2 mmol/L (40 mg/dL). However, due to CGM lag, the effect becomes fully visible about 20 minutes later. This strategy can also help increase Time in Tight Range (3.9 – 7.8 mmol/L or 70-140 mg/dL) if you start the activity when above 7.8 mmol/L or 140 mg/dL instead of above 10.0 mmol/L or 180 mg/dL).

Also, check out the graph, it extends two hours post-activity. Look at the reduction in the glucose area under the curve vs. matched pair analysis!!!!! That reduction in glucose exposure is very important for future health!

At 22:04, John summarises the key takeaways from the episode.

He reinforces that small, frequent movements throughout the day can help regulate glucose levels. Strategies such as “3 every 30” (three minutes of movement every 30 minutes), 20 minutes of walking before or after meals, and the “15 by 2” rule or “15 by 40” for reducing high glucose levels can be incredibly effective.

He also highlights that these approaches should be taught from the time of diagnosis and encourages families to adopt activity as part of everyday life, rather than seeing it as a diabetes-specific task.

At 24:23, John provides some important caveats. If glucose is above 14 mmol/L (250 mg/dL), ketones should be checked before using activity to lower glucose. If ketones are present, insulin should be given instead. He also stresses that movement should always be the individual’s choice and should not be enforced as a requirement. Instead, it should be framed as a valuable tool that can help improve glucose control and overall well-being.

Finally, John teases the next episode, which will focus on continuous glucose monitoring (CGM). He will be discussing CGM accuracy, how different systems compare, and how to select the right CGM based on personal needs. He encourages listeners to check out the show notes for research references, infographics, and practical tools to help implement activity snacking in daily life.

Check out this rap: 99 Problems, But Highs Ain’t One (click if you want to download it!)

Key Takeaways

  • Small movements can significantly improve glucose control.
  • “3 every 30” (three minutes of movement every 30 minutes) helps keep glucose in range.
  • Walking for 20 minutes before or after meals can reduce post-meal spikes.
  • If glucose is above 10 mmol/L (180 mg/dL), 15 minutes of movement can lower it by ~2 mmol/L (40 mg/dL).
  • Movement should be an option, not an obligation—everyone benefits from increased activity, not just people with diabetes.

Additional Resources

📄 Research Studies Referenced:

📌 Practical Tools & Guides:

Next Episode Series: The CGM Deep Dive!

John will be discussing the accuracy of CGM systems, how different devices compare, and how to select the best CGM for your needs.

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