Abstract
The possible association of habitual physical activity (PA) and the risk of pre-diabetes (Pre-DM) progression to type 2 diabetes (T2D) or the chance of returning to normoglycemia was investigated. This cohort study included 1167 Pre-DM individuals (mean age of 53.5 years, and 45.3% men) who participated in the third phase of the Tehran Lipid and Glucose Study (2006-2008) and followed up to a median of 9 years. PA, including leisure time and job activities, was measured using a reliable and validated Iranian version of the Modifiable Activity Questionnaire and reported as metabolic equivalent (MET)-minutes per week. The odds ratios (ORs) and 95% confidence intervals (CIs) of incident T2D and returning to normoglycemia were estimated in relation to PA levels (i.e., per every 500 MET-minutes/week, or across categories of PA levels < 600 as a reference, 600-1500 and > 1500 MET-minutes/week). During the study follow-up, 39.0 % progressed to T2D, and 37.8% returned to normoglycemia. Compared to subjects with a PA < 600 MET-minutes/week, the chance of regression to normoglycemia increased by 58% [OR = 1.58, 95% CI = 1.03-2.40 ∼ relative risk (RR) = 1.32, 95% CI = 1.02-1.63] among the participants who had a PA > 1500 MET-minutes/week. We further noted that each 500 MET-min/week activity corresponded to an elevated chance of returning to normoglycemia by 5% (OR = 1.05, 95% CI = 1.01-1.11). The study's findings provided evidence that higher daily PA levels may facilitate Pre-DM regression to normoglycemia. The beneficial effect of PA in Pre-DM subjects needs to exceed the recommended levels (i.e., 600 MET-minutes/week).