Exploring the association between BMI and mortality in Australian women and men with and without diabetes: the AusDiab study

Impact of Body Mass Index on All-Cause Mortality in Adults: A Systematic Review and Meta-Analysis

Background: Obesity is a risk factor for many diseases, diagnosed by calculating body mass index (BMI). Methods: To find an association between BMI and mortality in adults, we searched PubMed for articles published in the 21st century. Our review included 82 original studies, comprising 2.7 million patients and 23.4 million patient years. Results: The meta-analysis showed a U-shaped relationship between BMI and all-cause mortality risk, with the lowest mortality in the BMI range of 25-30 kg/m2. Subgroup analysis showed a J-shaped relationship, with greater risk in the highest BMI range (>35 kg/m2). Among the elderly, BMI values <20 kg/m2 were associated with the highest risk. Among diabetic patients, a U-shaped relationship was noticed, again with the highest risk in the lowest (<20 kg/m2) and highest BMI range (>35 kg/m2). Among patients with cardiovascular disease, the risk increased with BMI values <25 kg/m2 but did not noticeably change for BMI exceeding that value. Among cancer patients, the relationship was less pronounced than in other subgroups, with a slightly higher risk (>35 kg/m2). Conclusions: Our results show that the lowest mortality is observed among patients with BMI 25-30 kg/m2. Reduction of body mass should not be a universal recommendation in clinical practice, but it should be individualized.

The impact of obesity on different glucose tolerance status with incident cardiovascular disease and mortality events over 15 years of follow-up: a pooled cohort analysis

BACKGROUND

The effect of obesity in different glucose tolerance statuses i.e. normoglycemia (NGT), pre-diabetes, and type 2 diabetes (T2DM) on cardiovascular disease (CVD) and mortality has been an area of ongoing debate and uncertainty. In the present study, we aimed to examine the impact of being obese, whether general or central separately, in comparison with non-obese in different glucose tolerance statuses on the above outcomes.

METHODS

The study population included 18,184 participants aged 30-60 years (9927 women) from three longitudinal studies, including Atherosclerosis Risk in Communities, Multi-Ethnic Study of Atherosclerosis, and Tehran Lipid and Glucose Study. Glucose tolerance status was defined as NGT (fasting plasma glucose < 5.55 mmol/L), pre-diabetes (5.55-7.00 mmol/L), and T2DM (≥ 7 mmol/L or taking any medication for diabetes). Moreover, general and central obesity were defined based on body mass index and waist circumference (WC), respectively. Multivariable stratified Cox regression analysis was used to estimate hazard ratios (HRs (95% CI)) for CVD and mortality events.

RESULTS

During a 16-year follow-up, 2733 CVD events, 1101 CV mortality, and 3678 all-cause mortality events were recorded. We observed that being generally obese in comparison with non-obese increased the risk of CV and all-cause mortality in all glucose tolerance statuses; while considering CVD events, only among individuals with T2DM, the presence of general obesity was associated with marginally significant higher risk [1.19 (0.98-1.43); p-value = 0.07]. Regarding central adiposity, multivariate analysis revealed that elevated WC in NGT participants is associated with incident CVD [1.27(1.12-1.46)] and all-cause mortality [1.13(1.00-1.28)]. Moreover, central adiposity increased the risk of CV mortality in pre-diabetes individuals [1.47 (1.11-1.95)].

CONCLUSION

Findings from this pooled prospective cohort studies provide evidence that general obesity shows an unfavorable association with CV and all-cause mortality among the general population irrespective of their glucose tolerance statusThe findings imply that it's important to take into account the requirement and magnitude of weight reduction in people who are obese when offering guidance.

Obesity in heart failure with preserved ejection fraction with and without diabetes: risk factor or innocent bystander?

AIMS

Heart failure with preserved ejection fraction (HFpEF) is a condition that commonly coexists with type 2 diabetes mellitus (T2DM) and obesity. Whether the obesity-related survival benefit generally observed in HFpEF extends to individuals with concomitant T2DM is unclear. This study sought to examine the prognostic role of overweight and obesity in a large cohort of HFpEF with and without T2DM.

METHODS AND RESULTS

This large-scale cohort study included patients with HFpEF enrolled between 2010 and 2020. The relationship between body mass index (BMI), T2DM, and survival was assessed. A total of 6744 individuals with HFpEF were included, of which 1702 (25%) had T2DM. Patients with T2DM had higher BMI values (29.4 kg/m2 vs. 27.1 kg/m2, P < 0.001), higher N-terminal pro-brain natriuretic peptide values (864 mg/dL vs. 724 mg/dL, P < 0.001), and a higher prevalence of numerous risk factors/comorbidities than those without T2DM. During a median follow-up time of 47 months (Q1-Q3: 20-80), 2014 (30%) patients died. Patients with T2DM had a higher incidence of fatal events compared with those without T2DM, with a mortality rate of 39.2% and 26.7%, respectively (P < 0.001). In the overall cohort, using the BMI category 22.5-24.9 kg/m2 as the reference group, the unadjusted hazard ratio (HR) for all-cause death was increased in patients with BMI <22.5 kg/m2 [HR: 1.27 (confidence interval 1.09-1.48), P = 0.003] and decreased in BMI categories ≥25 kg/m2. After multivariate adjustment, BMI remained significantly inversely associated with survival in non-T2DM, whereas survival was unaltered at a wide range of BMI in patients with T2DM.

CONCLUSION

Among the various phenotypes of HFpEF, the T2DM phenotype is specifically associated with a greater disease burden. Higher BMI is linked to improved survival in HFpEF overall, while this effect neutralises in patients with concomitant T2DM. Advising BMI-based weight targets and weight loss may be pursued with different intensity in the management of HFpEF, particularly in the presence of T2DM.

Associations of BMI with all-cause mortality in normoglycemia, impaired fasting glucose and type 2 diabetes mellitus among an elderly Chinese population: a cohort study

Aim

To explore the associations of body mass index (BMI) and mortality among people with normal fasting glucose (NFG), impaired fasting glucose (IFG), and type 2 diabetes mellitus (T2DM) in an elderly Chinese population. 

Methods

A retrospective cohort study was conducted that included 59,874 elderly people who were aged 60 and older at baseline. Data for the study came from a health check-up program in China between 2011 and 2019. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using multivariable Cox proportional hazard models of BMI categories by glycemic status.

Results

During the median of 5.96 years of follow-up, 7928 participants died (6457/49057 with NFG, 712/5898 with IFG and 759/4919 with T2DM). In adjusted Cox models, risk of mortality showed a decreasing trend with BMI < 18.5 kg/m², 24 ≤ BMI < 28 kg/m², and BMI ≥ 28 kg/m² compared to 18.5 ≤ BMI < 24 kg/m²: HR (95% CI): 1.33 (1.18 to 1.49), 0.88 (0.83 to 0.93), and 0.90 (0.82 to 0.98), respectively, for NFG; 0.89 (0.55 to 1.46), 0.84 (0.71 to 0.99), and 0.88 (0.70 to 1.11), respectively, for IFG; and 1.42 (0.88 to 2.29), 0.75 (0.64 to 0.89), and 0.76 (0.62 to 0.93), respectively, for T2DM. There were curvilinear-shaped associations between BMI and mortality in the NFG and T2DM groups (P overall < 0.001 and P overall < 0.001, respectively; P nonlinearity < 0.001 and P nonlinearity = 0.027, respectively) and no significantly association between BMI and all-cause mortality was observed in the IFG group (P overall = 0.170).

Conclusion

High BMI compared to normal BMI was associated with decreased mortality, especially in the old populations with NFG and T2DM. Future studies are needed to explain the obesity paradox in elderly patients with T2DM.

The obesity paradox and diabetes

BACKGROUND

Obesity has been proven to be a risk factor for type 2 diabetes mellitus (T2DM) through numerous pathogenetic mechanisms. Unexpectedly, some studies suggest that subjects with overweight/obesity and T2DM have better clinical outcome than their normal weight peers. This finding is described as "obesity paradox" and calls into question the importance of weight loss in this specific population.

OBJECTIVE

This article is a narrative overview on the obesity and type 2 diabetes mellitus, particularly regarding the obesity paradox in T2DM patients.

METHODS

We used as sources MEDLINE/PubMed, CINAHL, EMBASE, and Cochrane Library, from inception to March 2020; we chose 30 relevant papers regarding the association of obesity with clinical outcome and mortality of patients affected by T2DM.

RESULTS

Many studies report that in patients with T2DM, overweight and obesity are associated with a better prognosis than underweight or normal weight, suggesting the presence of an obesity paradox. However, these studies have numerous limitations due to their mainly retrospective nature and to numerous confounding factors, such as associated pathologies, antidiabetic treatments, smoking habit, lack of data about distribution of body fat or weight history.

CONCLUSION

Literature data regarding the phenomenon of obesity paradox in T2DM patients are controversial due to the several limitations of the studies; therefore in the management of patients with overweight/obesity and T2DM is recommended referring to the established guidelines, which indicate diet and physical activity as the cornerstone of the treatment.

LEVEL OF EVIDENCE

Level V: narrative review.

Association between sleep duration and mortality risk among adults with type 2 diabetes: a prospective cohort study

AIMS/HYPOTHESIS

This study aimed to investigate whether the effects of sleep duration interacted with the presence of diabetes. We specifically sought to examine the relationship between sleep duration and all-cause and cause-specific mortality in people with type 2 diabetes across sex, age at diagnosis, duration of diabetes and treatment type.

METHODS

The sample consisted of 273,029 adults, including 248,817 without diabetes and 24,212 with type 2 diabetes, who participated in the National Health Interview Survey from 2004 to 2013 and whose data were linked to a mortality database up to 31 December 2015. Sleep duration was measured using self-report, whereby participants were asked 'on average how long do you sleep each day (≤5, 6, 7, 8, 9 or ≥10 h/day)?' The relationship between sleep duration and mortality risk was investigated using Cox proportional hazards regression model, with adjustments for demographics, BMI, lifestyle behaviours and clinical variables.

RESULTS

Absolute mortality rate was higher in adults with diabetes and extremes of sleep duration (≤5 h/day, 215.0 per 10,000 person-years; ≥10 h/day, 363.5 per 10,000 person-years). There was a non-significant interaction between sleep duration and the presence of diabetes (p for interaction = 0.08). A J-shaped relationship existed between sleep duration and all-cause mortality risk in people with type 2 diabetes. Compared with the reference group (7 h/day), both shorter and longer sleep durations were associated with increased risk of all-cause mortality (≤5 h/day, HR 1.24 [95% CI 1.09, 1.40]; 6 h/day, HR 1.13 [1.01, 1.28]; 8 h/day, HR 1.17 [1.06, 1.30]; ≥10 h/day, HR 1.83 [1.61, 2.08]). Similar associations were also observed for mortality risk from CVD, cancer, kidney disease, Alzheimer's disease and chronic lower respiratory diseases. Longer sleep duration in those with a younger age at diabetes onset was associated with greater risks of all-cause and CVD mortality. Shorter sleep duration in individuals treated with both insulin and oral glucose-lowering medication was also associated with higher risks of all-cause and CVD mortality.

CONCLUSIONS/INTERPRETATION

The associations between sleep duration and mortality risk may be different between diabetic and non-diabetic individuals. In people with type 2 diabetes, sleeping less or more than 7 h/day was associated with increased risk of all-cause and condition-specific mortality. The association was more prominent in those with a younger age at diabetes onset and receiving treatment with both oral glucose-lowering medication and insulin. This population may benefit from targeted sleep-related interventions to reduce the risks of adverse health outcomes. Graphical abstract.

Association of BMI, Fitness, and Mortality in Patients With Diabetes: Evaluating the Obesity Paradox in the Henry Ford Exercise Testing Project (FIT Project) Cohort

OBJECTIVE

To determine the effect of fitness on the association between BMI and mortality among patients with diabetes.

RESEARCH DESIGN AND METHODS

We identified 8,528 patients with diabetes (self-report, medication use, or electronic medical record diagnosis) from the Henry Ford Exercise Testing Project (FIT Project). Patients with a BMI <18.5 kg/m² or cancer were excluded. Fitness was measured as the METs achieved during a physician-referred treadmill stress test and categorized as low (<6), moderate (6-9.9), or high (≥10). Adjusted hazard ratios for mortality were calculated using standard BMI (kilograms per meter squared) cutoffs of normal (18.5-24.9), overweight (25-29.9), and obese (≥30). Adjusted splines centered at 22.5 kg/m² were used to examine BMI as a continuous variable.

RESULTS

Patients had a mean age of 58 ± 11 years (49% women) with 1,319 deaths over a mean follow-up of 10.0 ± 4.1 years. Overall, obese patients had a 30% lower mortality hazard (P < 0.001) compared with normal-weight patients. In adjusted spline modeling, higher BMI as a continuous variable was predominantly associated with a lower mortality risk in the lowest fitness group and among patients with moderate fitness and BMI ≥30 kg/m². Compared with the lowest fitness group, patients with higher fitness had an ∼50% (6-9.9 METs) and 70% (≥10 METs) lower mortality hazard regardless of BMI (P < 0.001).

CONCLUSIONS

Among patients with diabetes, the obesity paradox was less pronounced for patients with the highest fitness level, and these patients also had the lowest risk of mortality.