Long-term BMI change trajectories in Chinese adults and its association with the hazard of type 2 diabetes: evidence from a 20-year China Health and Nutrition Survey

Abstract

IntroductionTo investigate the relationship between long-term change trajectory in body mass index (BMI) and the hazard of type 2 diabetes among Chinese adults.Research design and methodsData were obtained from the China Health and Nutrition Survey (CHNS). Type 2 diabetes was reported by participants themselves in each survey wave. The duration of follow-up was defined as the period from the first visit to the first time self-reported type 2 diabetes, death, or other loss to follow-up from CHNS. The patterns of change trajectories in BMI were derived by latent class trajectory analysis method. The Fine and Gray regression model was used to estimate HRs with corresponding 95% CIs for type 2 diabetes.ResultsFour patterns of the trajectories of change in BMI were identified among Chinese adults, 42.7% of participants had stable BMI change, 40.8% for moderate BMI gain, 8.9% for substantial BMI gain and 7.7% for weight loss. During the follow-up with mean 11.2 years (158 637 person-years contributed by 14 185 participants), 498 people with type 2 diabetes (3.7%) occurred. Risk of type 2 diabetes was increased by 47% among people who gained BMI more substantially and rapidly (HR: 1.47, 95% CI 1.08 to 2.02, p=0.016) and increased by 20% among those in people with the moderate BMI gain (HR: 1.20, 95% CI 0.98 to 1.48, p=0.078), compared with those with stable BMI change.ConclusionsLong-term substantial gain of BMI was significantly associated with an increased risk of type 2 diabetes in the Chinese adults.

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“…Many studies have shown that obesity or overweight in childhood is likely to persist into adulthood [3][4][5][6][7]. Childhood obesity can lead to various health problems, even premature death [8][9][10]. Obesity and overweight have imposed a heavy economic burden on China and induces considerable medical expenditures each year [11][12][13].…”

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“…Evidence from large-scale prospective studies suggested that population with stable weight tended to have higher socioeconomic position, healthier lifestyle factors and consumed a healthier diet than those in weight change groups 26 , 30 . According to these studies and a priori knowledge about our data (results from the association between weight change pattern and risk of type 2 diabetes) 36 , a set of covariates were considered as potential confounders.…”

“…Participants were asked to report their current status of smoking in each wave, and were assigned to never or current smoker according to their answer to the question “Have you ever smoked cigarettes (including hand-rolled or device-rolled)” 36 , 37 . Alcohol consumption was classified into never or current, similar to smoking.…”

“…Amongst these variables, PA, smoking and drinking status and energy intake were predisposed as time-variant variables in large-scale cohort studies 36 , 42 . Therefore, in current analysis, the participant were assigned into 4 categories according to their changes smoking and alcohol consumption during follow-up period: (1) never to never (never smoking/drinking at baseline or the last survey wave), (2) never to current (begin smoking/drinking), (3) current to former (quit smoking/drinking), (4) current to current (keep smoking/drinking).…”

“…We also evaluated this assumption by visual inspection of log–log plots, which were consistent with proportional hazards. We completed the main analysis by assuming that variables were assumed to be missing completely at random (MCAR), consistent with pervious study 36 .…”