Activity Snacking to Increase Time in Range

The ATTD presentation and video

This episode previews John’s presentation at the Advanced Technologies and Treatments for Diabetes (ATTD) 2025 conference. The full video is below.

The presentation slides are also available: download the PowerPoint or download the PDF.

Why insulin alone is often not enough

Current exercise guidance recommends at least 30 minutes of moderate activity daily, plus two strength sessions per week for adults. For young people, the recommendation is one hour of daily activity. In practice, modern life makes this genuinely difficult — and for people with type 1 diabetes, the fear of hypoglycaemia adds a further barrier.

But the mechanism problem runs deeper. Injected insulin does not enter the portal vein — it is absorbed subcutaneously and reaches peripheral tissues first. When someone sits for long periods, blood flow to the skin slows, reducing insulin absorption. Blood flow to the kidneys increases, accelerating insulin clearance. The net effect is that subcutaneous insulin acts more slowly and less predictably when a person is sedentary.

How movement changes the picture

Physical activity increases blood flow to the skin, accelerating insulin absorption from the injection or infusion site. It also redirects blood flow towards muscle rather than the kidneys, directing more insulin to the tissues where it is needed. Additionally, exercise promotes non-insulin-mediated glucose uptake: muscles can absorb glucose directly without insulin as a mediator. All three effects work simultaneously.

The research: three key findings

3 every 30: the SIT-LESS study

Matthew Campbell’s SIT-LESS study found that just three minutes of movement every 30 minutes improved time in range by 14 percentage points. This is one of the most accessible strategies in all of diabetes management — it requires no equipment, no gym, and no dedicated exercise time.

Walking before meals

Lauren Turner’s research in Canada demonstrated that 20 minutes of walking before a meal reduces post-meal glucose rises. This is consistent with the mechanism above: pre-meal activity primes insulin absorption and increases muscle glucose uptake before the meal arrives.

Post-meal walking

A 2012 study found that walking for a few minutes every 30 minutes significantly reduced post-meal glucose levels in both people with and without diabetes.

The 15-by-2 rule and the T1DEXI evidence

When glucose is already elevated after a meal, waiting for a correction dose to take effect can mean hours of frustration and a glucose rollercoaster. The 15-by-2 rule describes what tends to happen on average in published research: 15 minutes of movement lowers glucose by approximately 2 mmol/L (40 mg/dL).

This is supported by a secondary analysis of the T1DEXI and DEXIP studies, which examined over 1,900 activity events in adults and adolescents with type 1 diabetes starting above 10 mmol/L (180 mg/dL). The analysis confirmed that movement consistently lowers glucose, regardless of exercise type, provided insulin has been given within the previous four hours. Without insulin on board, activity alone does not produce the same effect.

Matched pair analysis: 20 minutes, 20% drop

Unpublished data presented at Diabetes UK 2025 by Dr Cat Russon, under the supervision of Professor Rob Andrews at EXTOD, confirms the pattern in a matched pair design. The headline finding: 20 minutes of activity correlates with approximately a 20% drop in glucose. Due to CGM lag, the full effect becomes visible around 20 minutes after activity ends. The glucose area under the curve improvement extends for approximately two hours post-activity.