Ethnic-specific criteria for the metabolic syndrome: evidence from China

Metabolic effects of fructose and the worldwide increase in obesity

While virtually absent in our diet a few hundred years ago, fructose has now become a major constituent of our modern diet. Our main sources of fructose are sucrose from beet or cane, high fructose corn syrup, fruits, and honey. Fructose has the same chemical formula as glucose (C(6)H(12)O(6)), but its metabolism differs markedly from that of glucose due to its almost complete hepatic extraction and rapid hepatic conversion into glucose, glycogen, lactate, and fat. Fructose was initially thought to be advisable for patients with diabetes due to its low glycemic index. However, chronically high consumption of fructose in rodents leads to hepatic and extrahepatic insulin resistance, obesity, type 2 diabetes mellitus, and high blood pressure. The evidence is less compelling in humans, but high fructose intake has indeed been shown to cause dyslipidemia and to impair hepatic insulin sensitivity. Hepatic de novo lipogenesis and lipotoxicity, oxidative stress, and hyperuricemia have all been proposed as mechanisms responsible for these adverse metabolic effects of fructose. Although there is compelling evidence that very high fructose intake can have deleterious metabolic effects in humans as in rodents, the role of fructose in the development of the current epidemic of metabolic disorders remains controversial. Epidemiological studies show growing evidence that consumption of sweetened beverages (containing either sucrose or a mixture of glucose and fructose) is associated with a high energy intake, increased body weight, and the occurrence of metabolic and cardiovascular disorders. There is, however, no unequivocal evidence that fructose intake at moderate doses is directly related with adverse metabolic effects. There has also been much concern that consumption of free fructose, as provided in high fructose corn syrup, may cause more adverse effects than consumption of fructose consumed with sucrose. There is, however, no direct evidence for more serious metabolic consequences of high fructose corn syrup versus sucrose consumption.

Metabolic syndrome increases the risk of stroke: a 5-year follow-up study in a Chinese population

Limited information is available on the relationship between metabolic syndrome and stroke in the Chinese population. The aim of this study was to establish the prevalence of metabolic syndrome in the Chinese population and the relationship between stroke and metabolic syndrome in that population. 2,173 subjects aged 45 years and above without a history of stroke were recruited from six communities in Chongqing city, China. The participants were followed for incident stroke events (ischemic stroke and hemorrhagic stroke) for 5 years. Incidence rates and hazard ratios (HRs) for both subtypes of stroke were stratified by the presence or absence of metabolic syndrome and by each component. Among the subjects, women had a higher prevalence rate of metabolic syndrome than men (26 vs. 19%). As the number of metabolic syndrome components increased, HRs increased significantly, up to 5.1 (95% CI, 1.9-7.4) for ischemic stroke and 3.3 (95% CI, 1.7-5.7) for hemorrhagic stroke. We found that abdominal obesity had the highest HR (2.12, P < 0.001) for ischemic stroke, followed by metabolic syndrome (HR 1.65, P < 0.001). For hemorrhagic stroke, high blood pressure had the highest HR (2.17, P < 0.001), followed by abdominal obesity (HR 1.83, P < 0.001). After 5-year follow-up, the survival rates of stroke events were 94.2% among those with metabolic syndrome and 96.9% among those without. As the number of metabolic syndrome components increased, survival rates decreased progressively, from 99.6% for individuals with none of the components to 90.1% for those with four to five components. The results showed that metabolic syndrome is highly prevalent among the Chinese adult population and is associated with an increased risk for both ischemic stroke and hemorrhagic stroke.

All-cause and cardiovascular disease mortality increased with metabolic syndrome in Taiwanese

OBJECTIVE

This study aimed to investigate the relationship between mortality and metabolic syndrome using the America Heart Association/National Heart Lung Blood Institute (AHA/NHLBI) and International Diabetes Federation (IDF) definitions in a Taiwanese cohort.

METHODS AND PROCEDURES

A total of 124,513 participants, aged 20-94 years, from four nationwide health centers in Taiwan were recruited from 1998 to 1999. Cox proportional hazard regression analyses were used to estimate the relative risks (RRs) for all-cause and cardiovascular disease (CVD) mortality for those with metabolic syndrome compared to those without metabolic syndrome over 8 years of follow-up.

RESULTS

The baseline prevalence of metabolic syndrome was 22.4% by the AHA/NHLBI and 13.9% by the IDF definition. A total of 2,762 deaths (527 CVD) occurred. Using the AHA/NHLBI definition, the RRs (95% confidence intervals) of all-cause and CVD mortality were 1.21 (1.09-1.34) and 1.77 (1.40-2.24), respectively, in men and 1.30 (1.12-1.49) and 1.69 (1.19-2.42), respectively, in women. The association between metabolic syndrome and mortality was attenuated when using the IDF definition. Excluding subjects with diabetes or CVD at baseline, the RRs for CVD mortality still remained significant using the two definitions.

DISCUSSION

Metabolic syndrome, using either the AHA/NHLBI or IDF definitions, is a common disorder in Taiwanese adults and is similarly associated with an increase in all-cause and CVD mortality as found in Western populations. Our study suggests that Asians with metabolic syndrome are also at higher risk for death.

Development of diabetes in Chinese with the metabolic syndrome: a 6-year prospective study

OBJECTIVE

We investigated the association of the metabolic syndrome with new-onset diabetes in the Hong Kong Cardiovascular Risk Factor Prevalence Study cohort.

RESEARCH DESIGN AND METHODS

We followed up on 1,679 subjects without diabetes at baseline. Those with a previous diagnosis of diabetes or those who were receiving drug treatment were considered to be diabetic. The remaining subjects underwent a 75-g oral glucose tolerance test (OGTT). Diabetes was defined by plasma glucose > or =7.0 mmol/l with fasting and/or > or =11.1 mmol/l at 2 h.

RESULTS

The prevalences of the metabolic syndrome at baseline were 14.5 and 11.4%, respectively, according to U.S. National Cholesterol Education Program (NCEP) and International Diabetes Federation (IDF) criteria. After a median of 6.4 years, there were 66 and 54 new cases of diabetes in men and women, respectively. The metabolic syndrome at baseline predicted incident diabetes. Hazard ratios (HRs) for the NCEP and IDF definitions of the syndrome were 4.1 [95% CI 2.8-6.0] and 3.5 [2.3-5.2], respectively. HRs for fasting plasma glucose (FPG) > or =6.1 or 5.6 mmol/l were 6.9 [4.1-11.5] and 4.1 [2.8-6.0], respectively. The NCEP and IDF criteria had 41.9 and 31.7% sensitivity and 87.5 and 90.2% specificity, respectively. Their positive predictive values were low, approximately 20%, but their negative predictive values were approximately 95%.

CONCLUSIONS

The metabolic syndrome, particularly its component, elevated FPG, predicts diabetes in Chinese. An individual without the metabolic syndrome is unlikely to develop diabetes, but one who has it should practice therapeutic lifestyle changes and have periodic FPG measurements to detect new-onset diabetes.

Distributions of C-Reactive Protein and its Association With Metabolic Syndrome in Middle-Aged and Older Chinese People

OBJECTIVES

We evaluated the distributions of C-reactive protein (CRP) and its association with metabolic syndrome (MetS) in middle-aged and older Chinese people.

BACKGROUND

Several studies have suggested that CRP is a risk factor of MetS. However, it remains unclear how CRP levels are distributed and whether they are associated with MetS in Chinese people.

METHODS

We conducted a population-based cross-sectional survey in 2005 in Beijing and Shanghai, with a total of 1,458 men and 1,831 women age 50 to 70 years. Metabolic syndrome was defined according to the updated National Cholesterol Education Program Adult Treatment Panel III criteria for Asian Americans.

RESULTS

The median CRP level was 0.68 mg/l among the study population. The CRP levels were significantly higher among participants from Beijing or from urban areas than those in participants from Shanghai or from rural areas (p < 0.01). No gender difference in CRP levels was observed. The prevalence of MetS progressively increased with elevated CRP levels (p < 0.0001 for trend). In the highest quartile of CRP levels (>1.50 mg/l), the risk for MetS was substantially higher (odds ratio 5.97; 95% confidence interval 4.75 to 7.51) compared with that in the lowest quartile of CRP levels (< or =0.33 mg/l) after adjustment for age, gender, geographic location, lifestyle factors, educational attainment, and family history of chronic diseases. This association was observed in both obese and nonobese participants.

CONCLUSIONS

The overall plasma level of CRP is low but highly associated with the MetS among the middle-aged and elderly Chinese population. Prospective studies are needed to investigate the role of CRP in the development of MetS and related chronic diseases among Chinese people.

Regular alcohol consumption improves insulin resistance in healthy Japanese men independent of obesity

BACKGROUND

There is a great deal of controversy surrounding the relationship between alcohol consumption and insulin resistance. This association may be further confounded by the presence of obesity. We aimed to clarify whether regular alcohol consumption improves insulin resistance in healthy Japanese men and whether obesity affects this relationship.

METHODS

We examined 1029 men (ages 24 to 87 y) who had undergone medical checkups. They were divided into non-obese (body mass index (BMI) <25 kg/m(2)) or obese subjects (BMI > or =25 kg/m(2)) and further classified into non-regular drinkers (NRD), moderate drinkers (MD; 1-6 days/week), and daily drinkers (DD; 7 days/week). The homeostasis model assessment of insulin resistance (HOMA-IR) and other cardiac risk factors were compared between the groups.

RESULTS

In both non-obese and obese men, alcohol consumption decreased HOMA-IR in a dose-dependent manner, although HOMA-IR was about 2 times greater in obese men compared to non-obese men in any category (p<0.001). Stepwise logistic regression analysis revealed that alcohol consumption was the independent negative risk factor for HOMA-IR [OR, 0.576 (95% C.I. 0.402-0.824), p=0.003] after adjusting for age, BMI, systolic blood pressure, smoking status, LDL-cholesterol, HDL-cholesterol, and liver dysfunction.

CONCLUSIONS

Regular alcohol consumption improves insulin resistance in healthy Japanese men independent of obesity.

Ten-year risk of cardiovascular incidence related to diabetes, prediabetes, and the metabolic syndrome

BACKGROUND

The relative contributions of the metabolic syndrome (MetS) and dysglycemia on the risk of cardiovascular disease (CVD) have not been dissected. We aimed to compare MetS with dysglycemia in their association with the 10-year incidence risk of CVD.

METHODS

A total of 30,378 subjects were recruited from 11 provinces in the CMCS and followed-up for new coronary heart disease (CHD) and stroke events (ischemic stroke and hemorrhagic stroke) for 10 years. Incidence rates and HRs were estimated by the presence or absence of MetS, impaired fasting glucose (IFG) and diabetes, and by the various traits of MetS.

RESULTS

Among the subjects, 18.2% were defined as having MetS; 21.1% had IFG, and 6.8% had diabetes. Metabolic syndrome prevalence in IFG and diabetes was 38.1% and 48.7%, respectively, and the prevalence of IFG and diabetes in MetS was 44.1% and 18.3%, respectively. After adjusting for nonmetabolic risk factors, HRs of total CVD, CHD, and ischemic stroke in MetS were significant and higher than those in non-MetS, regardless of glycemic status. In the absence of MetS, the impact of dysglycemia was found only in IFG to CHD and diabetes to ischemic stroke. Hyperglycemia without any concomitant disorders was not associated with significantly higher risk of CVD.

CONCLUSIONS

The increased CVD risk in individuals with IFG or diabetes was largely driven by the coexistence of multiple metabolic disorders rather than hyperglycemia per se. Identification of clustering of metabolic abnormalities should be given more consideration in CVD prevention.