The World Health Organization (WHO) 2020 guidelines stipulate that adults should undertake at least 150 min, ideally 300 min of moderate-intensity physical activity per week, as this variable is key to achieving minutes of moderate-intensity physical activity per week, as this variable is key to achieving both primary and secondary prevention of people’s health. The WHO defines physical activity as “any bodily movement produced by skeletal muscles that requires energy expenditure”. These recommendations proposed by the WHO are primarily aimed at preventing the onset of cardiovascular diseases, obesity, type 2 diabetes mellitus (T2DM) and some forms of cancer.1 However, despite the known benefits of achieving the physical activity targets proposed by international bodies, their attainment continues to pose a significant challenge, particularly for the prevention and treatment of T2DM.2, 3 This challenge is particularly complex in patients with T2DM and middle-aged people living with overweight and older adults, who are more likely to be inactive and/or sedentary and have a lower exercise tolerance than healthy individuals.4, 5 Prescribing moderate-to-vigorous intensity physical activity (intensity greater than 3 MET) in these subjects is usually not very feasible to achieve and, in many cases, unattainable.6

Moreover, population studies have found that more than half of people manifest high sedentary behaviour (SB) during a typical day, understanding SB to comprise all activities - while awake - that require energy expenditure of less than 1.5 MET, such as: watching TV or sitting in front of the computer, reclining or lying down.7 It has specifically been shown that people with T2DM spend approximately 64% of their awake time in SB.8 This lifestyle is a global trend of particular concern since research suggests that long periods of SB are very harmful to health, irrespective of whether or not physical activity recommendations are achieved.9

Since 2016, the American Diabetes Association has proposed breaks in sedentary behaviour (BSB) as part of a healthy lifestyle for people with T2DM. BSB are defined as SB interrupted by a short bout of light physical activity (between 1.5 and 3.0 MET). This type of physical activity includes, but is not limited to, walking, going up and down stairs or doing squats. The ADA recommends interrupting sedentary behaviour with at least 3-min bouts of light physical activity every 30 min for people with diabetes mellitus.10 The ADA’s proposal is based on the powerful beneficial effects of BSB on cardiorespiratory fitness; skeletal muscle contraction-mediated glucose uptake and insulin response.11

There is a growing trend to focus exclusively on intentional and structured moderate-to-vigorous physical exercise. Yet this approach has clear limitations in people with morbidities.12 In this context, replacing prolonged time in SB with brief and light-standing activities could be more effective strategies for behaviour change, particularly if performed in the workplace. This is where people often spend much of their time in SB. BSB implemented in this way could be a useful tool to introduce people to a more active lifestyle, enabling them to achieve the appropriate physical activity recommendations for their health later.

Moreover, it is now known that it is not only the degree of exposure to hyperglycaemia - traditionally measured by long-term HbA1c (glycated haemoglobin) - that contributes to the pathogenesis of diabetes complications, but also glycaemic variability (GV), which evaluates short-term daily variations in blood glucose levels (within a single day or over consecutive days).13 GV in T2DM is associated with a higher risk of complications, particularly macrovascular complications,14 by increasing oxidative stress, pro-inflammatory markers and advanced glycation end products.15, 16, 17 As such, it is important not only to identify changes in the classic blood glucose indicators, such as the incremental area under the curve (iAUC) for glucose, fasting blood glucose and post-prandial blood glucose, or the dawn phenomenon (DP), but also GV and its indicators, such as time in range, time in hyperglycaemia, glucose standard deviation (SD), the coefficient of variation (CV) of glucose, the mean amplitude of glucose excursion (MAGE) and continuous overall net glycaemic action (CONGA).16, 17

In light of the above, it is extremely important to understand the evidence on the benefits of BSB, evaluated by robust physiological parameters of blood glucose control, to help prevent long-term complications in people with T2DM. As a result, the aim of this study was to analyse the short-term effects of different BSB regimens on the physiological parameters of blood glucose control in patients with T2DM.