Introduction
There has been a rise in the prevalence of type 2 diabetes (T2D) in the USA, which may be correlated with the increasing levels of obesity, poor dietary habits, and physical inactivity.1 In fact, an estimated 29.1 million Americans are currently living with T2D, with 1.4 million new cases being diagnosed each year.2 Over 422 million cases of T2D have been diagnosed worldwide.1 Diabetes is reported to be the 7th leading cause of death in the USA, and if left untreated, can lead to numerous health complications such as blindness, neuropathy, and infection. Through a combination of medication and healthy lifestyle behaviors (diet, physical activity), however, T2D can be effectively managed and individuals can live a full and healthy life.2
In response to the increase in prevalence of T2D, public health recommendations have promoted increases in moderate-to-vigorous physical activity (MVPA).3 However, there is emerging evidence that attention should also be focused on sedentary behavior (SB), which is directly related to chronic disease, independent of physical activity.4 ,5 In fact, SB has been associated with obesity, abnormal glucose metabolism, and the metabolic syndrome.6 In addition, a recent meta-analysis by Biswas et al7 found a 34% higher risk for all-cause mortality for prolonged sedentary time, even after adjusting for MVPA. Another meta-analysis by Wilmot et al8 found similar results, reporting that greater levels of SB were associated with a twofold increase in relative risk of T2D (RR=2.12 (1.61–2.78)) as compared to the group with the lowest levels of SB.
In addition to the effects of total sedentary time, the manner in which it is accumulated may also be important. Single bouts of prolonged, uninterrupted SB has been shown to decrease insulin sensitivity in adults, while additional evidence shows that breaking up bouts of SB may lead to improved metabolic profiles, however, few studies have examined these associations in individuals with T2D.3 ,9
In addition to physiological outcomes, evidence suggests that psychological outcomes may be connected to activity behavior, such that increases in MVPA may be associated with improved mood and psychological well-being in adults.10 Although the literature on SB and psychological well-being is less known, there have been a few studies suggesting that increases in SB may be associated with adverse behavioral outcomes such as depression.11 Poorer psychological health may be associated with poorer prognosis in individuals with T2D.12 Therefore, the purpose of this study was to examine the association between changes/improvements in MVPA and SB over a period of 6 months with physiological and psychological health outcomes for individuals recently diagnosed with T2D.