Exploring the non-linear association between BMI and mortality in adults with and without diabetes: the US National Health Interview Survey

Weight-adjusted waist index is not superior to conventional anthropometric indices for predicting type 2 diabetes: a secondary analysis of a retrospective cohort study

BACKGROUND

Weight-adjusted waist index (WWI) is a new anthropometric indicator to assess adiposity. Current knowledge regarding its association with type 2 diabetes mellitus (T2DM) is limited. This present study aims to evaluate the association of WWI with the risk of T2DM in the Japanese population, and to compare its predictive ability with body mass index (BMI) and waist circumference (WC).

METHODS

This was a secondary analysis of a retrospective cohort study involving 15,464 participants. Participants were divided into quartiles based on baseline WWI levels. Cox regression model, Kaplan-Meier curve, and smooth curve fitting were used to explore the relationship between WWI and T2DM. The discriminative ability of obesity indices in predicting T2DM was compared by the receiver operating characteristic (ROC) curve.

RESULTS

After a mean follow-up of 6.05 years, 373 participants were diagnosed with T2DM. In fully adjusted models, the risk of incident T2DM was 1.96 times higher for each 1-unit increment in WWI levels (95% CI: 1.61-2.39, P < 0.001). Smooth curve fitting analysis showed a linear positive association between baseline WWI and new-onset T2DM. Subgroup analysis showed consistent results which subjects in the 4th WWI quartile had the highest risk of developing T2DM in different age, gender, and BMI groups. WWI did not exhibit better predictive ability compared with BMI and WC in the results of ROC curve.

CONCLUSION

WWI, a new metabolic index, can be used to predict new-onset T2DM in the Japanese population. However, its predictive capability was not superior to conventional anthropometric indices.

Body mass index versus surrogate measures of central adiposity as independent predictors of mortality in type 2 diabetes

BACKGROUND

An "obesity paradox" for mortality has been shown in chronic disorders such as diabetes, and attributed to methodological bias, including the use of body mass index (BMI) for obesity definition. This analysis investigated the independent association of BMI versus surrogate measures of central adiposity with all-cause mortality in individuals with type 2 diabetes.

METHODS

The Renal Insufficiency And Cardiovascular Events Italian Multicentre Study is a prospective cohort study that enrolled 15,773 patients in 19 Italian centres in 2006-2008. Exposures were BMI and the surrogate measures of central adiposity waist circumference (WC), waist-to-height ratio (WHtR), and A Body Shape Index (ABSI). Vital status was retrieved on 31 October 2015 for 15,656 patients (99.3%), RESULTS: Age- and sex-adjusted hazard ratios and 95% confidence intervals were significantly higher in BMI-based underweight (1.729 [1.193-2.505), P = 0.004), moderately obese (1.214 [1.058-1.392), P = 0.006) and severely obese (1.703 [1.402-2.068), P < 0.0001), lower in overweight (0.842 [0.775-0.915), P < 0.0001) and similar in mildly obese (0.950 [0.864-1.045), P = 0.292), compared to normal-weight individuals. When further adjusting for smoking, physical activity (PA), and comorbidities, risk was lower also in mildly obese versus normal-weight patients. The BMI-mortality relationship did not change after sequentially excluding ever smokers, individuals with comorbidities, and those died within two years from enrollment and when analyzing separately participants below and above the median age. Conversely, a paradox relationship was observed among inactive/moderately inactive, but not moderately/highly active patients. Mortality risk adjusted for age, gender, smoking, PA and comorbidities was significantly higher in the highest tertile of WC (1.279 [1.089-1.501], P = 0.003), WHtR (1.372 [1.165-1.615], P < 0.0001), and ABSI (1.263 [1.067-1.495], P = 0.007) versus the lowest tertile. However, risk was lower in the intermediate versus lowest tertile for WC (0.823 [0.693-0.979], P = 0.028), similar for WHtR, and higher, though not significantly, for ABSI.

CONCLUSIONS

An "overweight paradox" remained after controlling for age, smoking, and comorbidities, arguing against a collider bias or reverse causation. However, it could be partly explained by confounding from PA level, possibly through its impact on lean mass and cardiorespiratory fitness. No obesity paradox was observed with WHtR and especially ABSI, which predicted mortality risk associated with central adiposity better than WC. Trial registration ClinicalTrials.gov, NCT00715481, 15 July, 2008.

Sex differences in the non-linear association between BMI and LDL cholesterol in middle-aged and older adults: findings from two nationally representative surveys in China

BACKGROUND

The relationship between body mass index (BMI) and low-density lipoprotein cholesterol (LDL-C) has not been clearly elucidated in middle-aged and older adults. This study aimed to evaluate the non-linear dose-response relationship between BMI and LDL-C in males and females.

METHODS

Data was obtained from two nationally representative surveys in China-the China Health and Nutrition Survey (CHNS, 2009) and China Health and Retirement Longitudinal Study (CHARLS, 2011-2012). To evaluate the sex differences in the association between BMI and LDL-C, the generalized additive models with a smooth function for continuous BMI and smooth-factor interaction for sexes with BMI were used. Segmented regressions were fitted to calculate the slopes with different estimated breakpoints among females and males.

RESULTS

A total of 12,273 participants (47.1% male) aged 45 to 75 years were included. The generalized additive models revealed that a non-linear relationship between BMI and LDL-C level in both sexes after adjustment for age, residence, education levels, marital status, drinking, smoking status, and cohort (CHNS or CHARLS). Slopes of the association between BMI and LDL-C association changed at BMI 20.3 kg/m2 (95% CI: 18.8 to 21.8) in females and 27.1 kg/m2 (95% CI: 25. 8 to 28.4) in males. Below these BMI breakpoints, LDL-C levels increased 1.84 (95% CI: 1.45 to 2.31) in males and 3.49 (95% CI: 1.54 to 5.45) mg/dL per kg/m2 in females. However, LDL-C levels declined - 1.50 (95% CI: - 2.92 to - 0.09) mg/dL per kg/m2 above BMI of 27.1 kg/m2 in males. The non-linear association BMI and LDL-C in males and females was varied by cohort source, age groups, and the number of metabolic syndrome criteria.

CONCLUSIONS

In the Chinese middle aged and older adults, the BMI and LDL-C relationship was inverted U-shaped with a high level of LDL-C at a BMI of 27.1 kg/m2 in males, and an approximately linear association was observed in females.

Long-term trends of BMI and cardiometabolic risk factors among adults with type 1 diabetes: An observational study from the German/Austrian DPV registry

AIMS

To analyse time-trends in BMI, obesity and cardiometabolic risk in adults with type 1 diabetes (T1DM) from the Diabetes Prospective Follow-up registry DPV.

METHODS

Data from 62,519 individuals with T1DM (age ≥ 18 years, BMI ≥ 18.5 kg/m²) were analysed. Multivariable regression models were used to determine time-trends in BMI, obesity and cardiometabolic risk and to identify predictors for increasing BMI. Results were compared to the NCD Risk Factor Collaboration (NCD-RisC) data for Germany.

RESULTS

Between 1999 and 2018 mean BMI increased from 25.0 kg/m² to 26.2 kg/m² in individuals with T1DM. This trend was most pronounced in young and middle-aged individuals (>21-55 years of age) and in those with higher baseline BMI. Insulin dose and diabetes duration were associated with increasing BMI. Between 1999 and 2016, the prevalence of obesity increased 1.8-fold in individuals with T1DM and 1.4-fold among the German population, respectively (NCD-RisC). Approximately 50-70% of individuals with obesity were insufficiently treated for hypertension and/or dyslipidaemia.

CONCLUSION

In adults with T1DM the prevalence of obesity is increasing at a faster pace than in the German population. BMI needs to be closely monitored, particularly during young adulthood, and cardiovascular risk factors need to be controlled better to prevent CVD and premature death.

Inflammation and Insulin Resistance as Risk Factors and Potential Therapeutic Targets for Alzheimer's Disease

Overnutrition and modern diets containing high proportions of saturated fat are among the major factors contributing to a low-grade state of inflammation, hyperglycemia and dyslipidemia. In the last decades, the global rise of type 2 diabetes and obesity prevalence has elicited a great interest in understanding how changes in metabolic function lead to an increased risk for premature brain aging and the development of neurodegenerative disorders such as Alzheimer's disease (AD). Cognitive impairment and decreased neurogenic capacity could be a consequence of metabolic disturbances. In these scenarios, the interplay between inflammation and insulin resistance could represent a potential therapeutic target to prevent or ameliorate neurodegeneration and cognitive impairment. The present review aims to provide an update on the impact of metabolic stress pathways on AD with a focus on inflammation and insulin resistance as risk factors and therapeutic targets.

Burden and Consequences of Financial Hardship From Medical Bills Among Nonelderly Adults With Diabetes Mellitus in the United States

Background:

The trend of increasing total and out-of-pocket expenditure among patients with diabetes mellitus represents a risk of financial hardship for Americans and a threat to medical and nonmedical needs. We aimed to describe the national scope and associated tradeoffs of financial hardship from medical bills among nonelderly individuals with diabetes mellitus.

Methods and Results:

We used the National Health Interview Survey data from 2013 to 2017, including adults ≤64 years old with a self-reported diagnosis of diabetes mellitus. Among 164 696 surveyed individuals, 8967 adults ≤64 years old reported having diabetes mellitus, representing 13.1 million individuals annually across the United States. The mean age was 51.6 years (SD 10.3), and 49.1% were female. A total of 41.1% were part of families that reported having financial hardship from medical bills, with 15.6% reporting an inability to pay medical bills at all. In multivariate analyses, individuals who lacked insurance, were non-Hispanic black, had low income, or had high-comorbidity burden were at higher odds of being in families with financial hardship from medical bills. When comparing the graded categories of financial hardship, there was a stepwise increase in the prevalence of high financial distress, food insecurity, cost-related nonadherence, and foregone/delayed medical care, reaching 70.5%, 49.4%, 49.5%, and 74% among those unable to pay bills, respectively. Compared with those without diabetes mellitus, individuals with diabetes mellitus had higher odds of financial hardship from medical bills (adjusted odds ratio [aOR], 1.27 [95% CI, 1.18–1.36]) or any of its consequences, including high financial distress (aOR, 1.14 [95% CI, 1.05–1.24]), food insecurity (aOR, 1.27 [95% CI, 1.16–1.40]), cost-related medication nonadherence (aOR, 1.43 [95% CI, 1.30–1.57]), and foregone/delayed medical care (aOR, 1.30 [95% CI, 1.20–1.40]).

Conclusions:

Nonelderly patients with diabetes mellitus have a high prevalence of financial hardship from medical bills, with deleterious consequences.

Differential relationship between waist circumference and mortality according to age, sex, and body mass index in Korean with age of 30-90 years; a nationwide health insurance database study

BACKGROUND

A recent concept is that obesity, assessed by body mass index (BMI), is not always a sign of poor health. Thus, in order to use obesity metrics in clinical decision making, it is important to clarify the relationship between waist circumference (WC), a proxy for abdominal obesity, and mortality.

METHODS

Data were used from 8,796,759 subjects aged between 30 and 90 years, who had participated in the Korea National Health Screening Examination between January 1, 2009 and December 31, 2009 and survived at least 1 year post screening. Data from a mean follow-up time of an additional 5.3 years (time at risk) were analyzed for the relationship between WC and mortality according to age, sex, and BMI category.

RESULTS

An increased WC of more than 90 cm in men and 85 cm in women showed a definite negative influence on mortality. However, the detailed relationship between WC and mortality was J-shaped or U-shaped according to age, sex, and BMI category. In the normal BMI group, the optimal WC range with the lowest mortality was < 70 cm in men and 70-75 cm in women, whereas in obese individuals a WC between 80 and 90 cm in men and 75 and 85 cm in women showed the lowest mortality. The association between increased WC and higher mortality tended to be more obvious in normal-weight women than in normal-weight men or obese women. Furthermore, in normal-weight and obese women, the effect of increased WC on mortality was more critical for subjects aged < 60 years rather than those aged ≥ 60 years.

CONCLUSIONS

Abdominal obesity, as measured by WC, showed a significant negative association on mortality, and its association with mortality was different according to age, sex, and BMI category. Therefore, WC should be considered in the assessment of obesity-related health risks, and individualized cut-off points for the definition of a healthy WC according to age, sex, and BMI category are necessary.

Sitting Time in Adults 65 Years and Over: Behavior, Knowledge, and Intentions to Change

This study examined sitting time, knowledge, and intentions to change sitting time in older adults. An online survey was completed by 494 Australians aged 65+. Average daily sitting was high (9.0 hr). Daily sitting time was the highest during TV (3.3 hr), computer (2.1 hr), and leisure (1.7 hr). A regression analysis demonstrated that women were more knowledgeable about the health risks of sitting compared to men. The percentage of older adults intending to sit less were the highest for TV (24%), leisure (24%), and computer (19%) sitting time. Regression analyses demonstrated that intentions varied by gender (for TV sitting), education (leisure and work sitting), body mass index (computer, leisure, and transport sitting), and physical activity (TV, computer, and leisure sitting). Interventions should target older adults' TV, computer, and leisure time sitting, with a focus on intentions in older males and older adults with low education, those who are active, and those with a normal weight.

BMI, Waist Circumference and All-Cause Mortality in a Middle-Aged and Elderly Chinese Population

OBJECTIVE

To investigate the association of obesity and all-cause mortality in a sample of middle-aged and elderly population.

DESIGN AND SETTING

Information of participants was collected in the Dongfeng-Tongji study, a perspective cohort study of Chinese occupational population. The main outcome was risk of death after 8.5 years of follow-up.

PARTICIPANTS AND MEASUREMENTS

We examined the association of BMI, waist circumference (WC, and waist-height ratio (WHtR) with all-cause mortality in the Dongfeng-Tongji cohort study (n=26,143). Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CI) for all-cause mortality. Area under the receiver operating characteristic curves and net reclassification improvement (NRI) were used to calculate the power of prediction models.

RESULTS

During a mean of 8.5 years of follow-up, 2,246 deaths were identified. There is a U-shaped association of BMI with all-cause mortality in the middle-aged and elderly Chinese population. Compared with individuals with normal BMI, underweight was positively (HR=2.16, 95% CI: 1.73, 2.69) while overweight (HR=0.75, 95% CI: 0.67, 0.84) and obesity (HR=0.67, 95% CI: 0.56, 0.79) were negatively associated with all-cause mortality after adjustment for potential confounders including WC. In contrast, WC (Q5 vs. Q1, HR=1.55, 95% CI: 1.29, 1.86) and WHtR (Q5 vs.Q1, HR=1.69, 95% CI: 1.40, 2.04) were positively associated with mortality after further adjustment for BMI (P trend < 0.001). Addition of both BMI and WC into the all-cause mortality predictive model significantly increased AUC (P =0.0002) and NRI (NRI = 2.57%, P = 0.0007).

CONCLUSIONS

BMI and WC/WHtR were independently associated with all-cause mortality after mutual adjustment. Combination of BMI and WC/WHtR improved the predictive ability of all-cause mortality risk in the middle-aged and elderly population.

Body mass index and all-cause mortality among type 2 diabetes mellitus patients: Findings from the 5-year follow-up of the MADIABETES cohort

PURPOSE

To analyse the association between body mass index (BMI) and all-cause mortality in a 5-year follow-up study with Spanish type 2 diabetes mellitus (T2DM) patients, seeking gender differences.

METHODS

3443 T2DM outpatients were studied. At baseline and annually, patients were subjected to anamnesis, a physical examination, and biochemical tests. Data about demographic and clinical characteristics was also recorded, as was the treatment each patient had been prescribed. Mortality records were obtained from the Spanish National Institute of Statistics. Survival curves for BMI categories (Gehan-Wilcoxon test) and a multivariate Cox proportional hazard analysis were performed to identify adjusted Hazard Ratios (HRs) of mortality.

RESULTS

Mortality rate was 26.38 cases per 1000patient-years (95% CI, 23.92-29.01), with higher rates in men (28.43 per 1000patient-years; 95% CI, 24.87-32.36) than in women (24.31 per 1000patient-years; 95% CI, 21.02-27.98) (p=0.079). Mortality rates according to BMI categories were: 56.7 (95% CI, 40.8-76.6), 28.4 (95% CI, 22.9-34.9), 24.8 (95% CI, 21.5-28.5), 21 (95% CI, 16.3-26.6) and 23.7 (95% CI, 14.3-37) per 1000person-years for participants with a BMI of <23, 23-26.8, 26.9-33.1, 33.2-39.4, and >39.4kg/m², respectively. The BMI values associated with the highest all-cause mortality were <23kg/m², but only in males [HR: 2.78 (95% CI, 1.72-4.49; p<0.001)], since in females this association was not significant [HR: 1.14 (95% CI, 0.64-2.04; p=0.666)] (reference category for BMI: 23.0-26.8kg/m²). Higher BMIs were not associated with higher mortality rates.

CONCLUSIONS

In an outpatient T2DM Mediterranean population sample, low BMI predicted all-cause mortality only in males.

Body Mass Index and Mortality

Although the prevalence of obesity, a well-known risk factor for various chronic diseases such as hypertension, type 2 diabetes and dyslipidemia, is rapidly increasing worldwide, the association of obesity with all-cause mortality remains controversial. Many previous epidemiologic studies have demonstrated a U-shaped relationship between obesity and mortality, suggesting that there is an obesity paradox. However, recent large-scale meta-analyses found contradictory results that both overweight and obese subjects exhibited a significant increase in all-cause mortality. This review summarizes the key epidemiologic studies on the association of obesity with mortality and thoroughly examines the causes of the obesity paradox and the precautions needed in the interpretation of this clinical evidence.