Abdominal visceral and subcutaneous adipose tissue and associations with cardiometabolic risk in Inuit, Africans and Europeans: a cross-sectional study.
Abdominal fat has been identified as a risk marker of cardiometabolic disease independent of overall adiposity. However, it is not clear whether there are ethnic disparities in this risk. We investigated the associations of visceral adipose tissue (VAT) and abdominal subcutaneous adipose tissue (SAT) with cardiometabolic risk factors in three ethnic diverse populations of Inuit, Africans and Europeans.
Cross-sectional pooled study.
Greenland, Kenya and Denmark.
A total of 5113 participants (2933 Inuit, 1397 Africans and 783 Europeans) from three studies in Greenland, Kenya and Denmark were included. Measurements included abdominal fat distribution assessed by ultrasound, oral glucose tolerance test, hepatic insulin resistance, blood pressure and lipids. The associations were analysed using multiple linear regressions.
Across ethnic group and gender, an increase in VAT of 1 SD was associated with higher levels of hepatic insulin resistance (ranging from 14% to 28%), triglycerides (8% to 16%) and lower high-density lipoprotein cholesterol (HDL-C, -1.0 to -0.05 mmol/L) independent of body mass index. VAT showed positive associations with most of the other cardiometabolic risk factors in Inuit and Europeans, but not in Africans. In contrast, SAT was mainly associated with the outcomes in Inuit and Africans. Of notice was that higher SAT was associated with higher HDL-C in African men (0.11?mmol/L, 95% CI: 0.03 to 0.18) and with lower HDL-C in Inuit (-0.07?mmol/L, 95% CI: -0.12 to -0.02), but not in European men (-0.02?mmol/L, 95% CI: -0.09 to 0.05). Generally weaker associations were observed for women. Furthermore, the absolute levels of several of the cardiometabolic outcomes differed between the ethnic groups.
VAT and SAT were associated with several of the cardiometabolic risk factors beyond overall adiposity. Some of these associations were specific to ethnicity, suggesting that ethnicity plays a role in the pathway from abdominal fat to selected cardiometabolic risk factors.
We studied the association and agreement between questionnaire data and biomarkers of marine food among Greenland Inuit.
Cross sectional study.
The study population comprised 2,224 Inuit, age 18+ (43% men); data collected 2005-2008 in Greenland. Using a food frequency questionnaire (FFQ), we calculated consumption of seal, whale, and fish (g/day) and as meals/month, intake of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), total N3, and mercury. We measured erythrocyte membrane fatty acids (FA) and whole blood mercury (Hg). Associations were assessed by Pearson correlation and agreement between the 2 methods was assessed by Bland-Altman plots depicting mean difference between the methods. Using multiple linear regressions, the associations were studied between whole blood mercury, erythrocyte FA and frequency or gram per day of seal, whale, and fish.
To examine the association between birth weight and glucose intolerance in adult Greenlandic Inuit.
We examined 1429 participants aged 18-56?years from two population-based, cross-sectional studies in Greenland with information on birth weight. Oral glucose tolerance tests, anthropometric measures and ultrasound of abdominal tissue were performed. Associations of birth weight with glucose markers were analysed using linear or logistic regressions. Spline analyses were conducted to examine u-shaped associations. Adjustments were done for age, sex, birth place, family history of diabetes, genetic admixture, TBC1D4 p.Arg684Ter carrier status, BMI and visceral adipose tissue.
The median birthweight was 3300?g and 3.9% had type 2 diabetes, T2DM. Spline analyses indicated overall linear associations. In fully adjusted analyses, an increase in birth weight of 1?kg was associated with a change in fasting plasma glucose of -0.06?mmol/L (95%CI: -0.11, -0.01), 2-h plasma glucose of -0.16?mmol/L (95%CI: -0.35, 0.02), HOMA-IR of -5.45% (95%CI: -10.34, -0.29), insulin sensitivity index of 7.04% (95%CI: 1.88, 12.45) and a trend towards a reduced risk of hyperglycaemia and T2DM, although statistically insignificant.
Birth weight was inversely associated with hepatic and peripheral insulin resistance independently of adult adiposity. Thus, the findings support low birth weight as a contributing factor for glucose intolerance in adult Inuit in Greenland.
To examine the association between birth weight and glucose intolerance in adult Greenlandic Inuit.
We examined 1429 participants aged 18-56?years from two population-based, cross-sectional studies in Greenland with information on birth weight. Oral glucose tolerance tests, anthropometric measures and ultrasound of abdominal tissue were performed. Associations of birth weight with glucose markers were analysed using linear or logistic regressions. Spline analyses were conducted to examine u-shaped associations. Adjustments were done for age, sex, birth place, family history of diabetes, genetic admixture, TBC1D4 p.Arg684Ter carrier status, BMI and visceral adipose tissue.
The median birthweight was 3300?g and 3.9% had type 2 diabetes, T2DM. Spline analyses indicated overall linear associations. In fully adjusted analyses, an increase in birth weight of 1?kg was associated with a change in fasting plasma glucose of -0.06?mmol/L (95%CI: -0.11, -0.01), 2-h plasma glucose of -0.16?mmol/L (95%CI: -0.35, 0.02), HOMA-IR of -5.45% (95%CI: -10.34, -0.29), insulin sensitivity index of 7.04% (95%CI: 1.88, 12.45) and a trend towards a reduced risk of hyperglycaemia and T2DM, although statistically insignificant.
Birth weight was inversely associated with hepatic and peripheral insulin resistance independently of adult adiposity. Thus, the findings support low birth weight as a contributing factor for glucose intolerance in adult Inuit in Greenland.
The Inuit population in Greenland has undergone rapid socioeconomic and nutritional changes simultaneously with an increasing prevalence of obesity. Therefore, the objective was to examine fetal programming as part of the aetiology of obesity among Inuit in Greenland by investigating the association between birth weight and measures of body composition and fat distribution in adulthood.
The study was based on cross-sectional data from a total of 1,473 adults aged 18-61 years in two population-based surveys conducted in Greenland between 1999-2001 and 2005-2010. Information on birth weight was collected from birth records. Adiposity was assessed by anthropometry, fat mass index (FMI), fat-free mass index (FFMI), and visceral (VAT) and subcutaneous adipose tissue (SAT) estimated by ultrasound. The associations to birth weight were analyzed using linear regression models and quadratic splines. Analyses were stratified by sex, and adjusted for age, birthplace, ancestry and family history of obesity.
Spline analyses showed linear relations between birth weight and adult adiposity. In multiple regression analyses, birth weight was positively associated with BMI, waist circumference, FMI, FFMI and SAT with generally weaker associations among women compared to men. Birth weight was only associated with VAT after additional adjustment for waist circumference and appeared to be specific and inverse for men only.
Higher birth weight among Inuit was associated with adiposity in adulthood. More studies are needed to explore a potential inverse association between birth size and VAT.
Cardiovascular disease (CVD) is a major public health issue in indigenous populations in the Arctic. These diseases have emerged concomitantly with profound social changes over the past 60 years. The aim of this study was to summarize the literature on CVD risk among Arctic Inuit. Literature on prevalence, incidence, and time trends for CVD and its risk factors in Arctic Inuit populations was reviewed. Most evidence supports a similar incidence of coronary heart disease and a higher incidence of cerebrovascular disease among Arctic Inuit than seen in western populations. Factors that may increase CVD risk include aging of the population, genetic susceptibility, and a rapid increase in obesity, diabetes, and hypertension in parallel with decreasing physical activity and deterioration of the lipid profile. In contrast, and of great importance, there has been a decrease in smoking and alcohol intake (at least documented in Greenland), and contaminant levels are declining. Although there have been marked socioeconomic and dietary changes, it remains unsolved and to some extent controversial how this may have influenced cardiovascular risk among Arctic Inuit. The increase in life expectancy, in combination with improved prognosis for patients with manifest CVD, will inevitably lead to a large increase in absolute numbers of individuals affected by CVD in Arctic Inuit populations, exacerbated by the rise in most CVD risk factors over the past decades. For preventive purposes and for health care planning, it is crucial to carefully monitor disease incidence and trends in risk factors in these vulnerable Arctic populations.
Studies of diabetes in migrant populations have shown a higher prevalence compared to their respective countries of origin and to people natively born in the host country, but there is little population-based data on diabetes incidence and mortality in migrant populations. The aim of the current study was (1) to describe the incidence rates and prevalence of diabetes among first generation migrants in Denmark compared to the Danish background population, and (2) to compare standardised mortality rates (SMRs) for individuals with and without diabetes according to country of origin.
Information was obtained from linkage of the National Diabetes Register with mortality statistics and information from the Central Personal Register on country of origin. Age- and sex-specific estimates of prevalence, incidence rates, mortality rates and SMRs relative to the part of the population without diabetes were calculated based on follow up of the entire Danish population.
Compared with native born Danes, the incidence of diabetes was about 2.5 times higher among migrants from Africa, Asia, and the Middle East, and these migrant groups also showed significantly higher prevalence. The standardised mortality rates (SMR) were higher particularly above 50years of age among most migrant groups compared with native born Danes, and with a higher annual increase.
The highest diabetes incidence rates and prevalence estimates were observed among migrants from Africa, Asia, and the Middle East, and the annual increase in SMRs was higher in these groups compared to native born Danes.
Health changes in Greenland have evolved in association with rapid social changes, ageing of the population, urbanisation, changes in diet and physical activity. Two population-based studies found a notably high prevalence of diabetes (9%) and pre-diabetes (19%) among Greenland Inuit. Contrary to most other studies, the highest prevalence of diabetes and pre-diabetes was observed in the least urbanised areas, and the traditional Inuit diet was associated with a higher risk of glucose intolerance. A recent study identified a strong association of a common TBC1D4 nonsense variant with diabetes.
Cardiovascular disease (CVD) is a well-known complication of diabetes, but the association has not been studied among Inuit in Greenland. The aim was to examine the association between diabetes and incident CVD among Inuit in Greenland and determine if the common diabetogenic TBC1D4 variant confers increased risk of CVD. We followed an initial study population of 4127 adults in Greenland who had participated in at least one population-based health survey, in national registers. We used Poisson regression to calculate incidence rate ratios (IRR) of cardiovascular endpoints, comparing participants with and without diabetes and comparing homozygous TBC1D4 carriers with heterozygous carriers and non-carriers combined. Close to 10% had diabetes and age range was 18-96 years (45% male). Of the 3924 participants without prior CVD, 362 (~?9%) had CVD events during a median follow-up of 10 years. Multivariate IRR for the effect of diabetes on CVD was 1.12 (95% CI: 0.80, 1.57) p?=?0.50. Using a recessive genetic model, we compared homozygous TBC1D4 carriers with wildtype and heterozygous carriers combined, with a multivariate IRR of 1.20 (95% CI: 0.69, 2.11) p?=?0.52. Neither diabetes nor the TBC1D4 variant significantly increased CVD risk among Inuit in Greenland in adjusted models.
Cardiovascular disease (CVD) is a well-known complication of diabetes, but the association has not been studied among Inuit in Greenland. The aim was to examine the association between diabetes and incident CVD among Inuit in Greenland and determine if the common diabetogenic TBC1D4 variant confers increased risk of CVD. We followed an initial study population of 4127 adults in Greenland who had participated in at least one population-based health survey, in national registers. We used Poisson regression to calculate incidence rate ratios (IRR) of cardiovascular endpoints, comparing participants with and without diabetes and comparing homozygous TBC1D4 carriers with heterozygous carriers and non-carriers combined. Close to 10% had diabetes and age range was 18-96 years (45% male). Of the 3924 participants without prior CVD, 362 (~?9%) had CVD events during a median follow-up of 10 years. Multivariate IRR for the effect of diabetes on CVD was 1.12 (95% CI: 0.80, 1.57) p?=?0.50. Using a recessive genetic model, we compared homozygous TBC1D4 carriers with wildtype and heterozygous carriers combined, with a multivariate IRR of 1.20 (95% CI: 0.69, 2.11) p?=?0.52. Neither diabetes nor the TBC1D4 variant significantly increased CVD risk among Inuit in Greenland in adjusted models.
