Redefining type 2 diabetes: 'diabesity' or 'obesity dependent diabetes mellitus'?

Development of diabesity in mice with neuronal deletion of Shp2 tyrosine phosphatase

Obesity and diabetes, termed "diabesity," are serious health problems that are increasing in frequency. However, the molecular mechanisms and neuronal regulation of these metabolic disorders are not fully understood. We show here that Shp2, a widely expressed Src homology 2-containing Tyr phosphatase, plays a critical role in the adult brain to control food intake, energy balance, and metabolism. Mice with a neuron-specific, conditional Shp2 deletion were generated by crossing a pan-neuronal Cre-line (CRE3) with Shp2(flox/flox) mice. These congenic mice, CRE3/Shp2-KO, developed obesity and diabetes and the associated pathophysiological complications that resemble those encountered in humans, including hyperglycemia, hyperinsulinemia, hyperleptinemia, insulin and leptin resistance, vasculitis, diabetic nephropathy, urinary bladder infections, prostatitis, gastric paresis, and impaired spermatogenesis. This mouse model may help to elucidate the molecular mechanisms that lead to the development of diabesity in humans and provide a tool to study the in vivo complications of uncontrolled diabetes.

Pathogenic potential of adipose tissue and metabolic consequences of adipocyte hypertrophy and increased visceral adiposity

When caloric intake exceeds caloric expenditure, the positive caloric balance and storage of energy in adipose tissue often causes adipocyte hypertrophy and visceral adipose tissue accumulation. These pathogenic anatomic abnormalities may incite metabolic and immune responses that promote Type 2 diabetes mellitus, hypertension and dyslipidemia. These are the most common metabolic diseases managed by clinicians and are all major cardiovascular disease risk factors. 'Disease' is traditionally characterized as anatomic and physiologic abnormalities of an organ or organ system that contributes to adverse health consequences. Using this definition, pathogenic adipose tissue is no less a disease than diseases of other body organs. This review describes the consequences of pathogenic fat cell hypertrophy and visceral adiposity, emphasizing the mechanistic contributions of genetic and environmental predispositions, adipogenesis, fat storage, free fatty acid metabolism, adipocyte factors and inflammation. Appreciating the full pathogenic potential of adipose tissue requires an integrated perspective, recognizing the importance of 'cross-talk' and interactions between adipose tissue and other body systems. Thus, the adverse metabolic consequences that accompany fat cell hypertrophy and visceral adiposity are best viewed as a pathologic partnership between the pathogenic potential adipose tissue and the inherited or acquired limitations and/or impairments of other body organs. A better understanding of the physiological and pathological interplay of pathogenic adipose tissue with other organs and organ systems may assist in developing better strategies in treating metabolic disease and reducing cardiovascular disease risk.

Evolutionary origins of obesity

Although it appeared relatively suddenly, the current obesity epidemic - largely manifest in industrialized societies but now spreading to the rest of the world - is the result of interaction between human biology and human culture over the long period of human evolution. As mammals and primates, humans have the capacity to store body fat when opportunities to consume excess energy arise. But during the millions of years of human evolution such opportunities were rare and transient. More commonly ancestral hominins and modern humans were confronted with food scarcity and had to engage in high levels of physical activity. In tandem with encephalization, humans evolved elaborate and complex genetic and physiological systems to protect against starvation and defend stored body fat. They also devised technological aids for increasing energy consumption and reducing physical effort. In the last century, industrialization provided access to great quantities of mass-produced, high-calorie foods and many labour-saving and transportation devices, virtually abolishing starvation and heavy manual work. In the modern obesogenic environment, individuals possessing the appropriate combination of ancestral energy-conserving genes are at greater risk for overweight and obesity and associated chronic diseases.

Tagatose, a new antidiabetic and obesity control drug

A potentially important new drug for treating type 2 diabetes, tagatose, is now in phase 3 clinical trial. The history, development, additional health benefits, mechanisms of action and the potential for the drug are presented in context with a review of the rapidly growing epidemic of type 2 diabetes and treatments for it. An epimer of fructose, the natural hexose tagatose was originally developed by Spherix Incorporated (formerly Biospherics Inc.) as a low-calorie sugar substitute. Only 20% of orally ingested tagatose is fully metabolized, principally in the liver, following a metabolic pathway identical to that of fructose. Following a decade of studies, tagatose became generally recognized as safe for use in foods and beverages under US FDA regulation. The simple sugar is commercially produced by isomerization of galactose, which is prepared from lactose. Early human studies suggested tagatose as a potential antidiabetic drug through its beneficial effects on postprandial hyperglycaemia and hyperinsulinaemia. A subsequent 14-month trial confirmed its potential for treating type 2 diabetes, and tagatose showed promise for inducing weight loss and raising high-density lipoprotein cholesterol, both important to the control of diabetes and constituting benefits independent of the disease. Furthermore, tagatose was shown to be an antioxidant and a prebiotic, both properties cited in the maintenance and promotion of health. No current therapies for type 2 diabetes provide these multiple health benefits. The predominant side effects of tagatose are gastrointestinal disturbances associated with excessive consumption, generally accommodated within 1- to 2-week period. The health and use potentials for tagatose (branded Naturlose((R)) for this use) are given with respect to current type 2 diabetes drugs and markets. Under an FDA-affirmed protocol, Spherix is currently conducting a phase 3 trial to evaluate a placebo-subtracted treatment effect based on a decrease in HbA(1c) levels. Side effects, contraindications and possibly beneficial new findings will be carefully monitored. It is hoped that early results of the trial may become available by mid-2008. If a subsequent NDA is successful, tagatose may fill a major health need.

An epidemiological overview of diabetes across the world

Once the Cinderella of chronic diseases, diabetes mellitus is now fast emerging as one of the biggest health catastrophes the world has ever witnessed. Almost 6% of the world's adult population now live with diabetes (Sicree et al, 2003; International Federation of Diabetes, 2006). It has been predicted that the total number of people with diabetes will rise to 366 million in less than 30 years if preventative action is not taken (Wild et al, 2004). Diabetes is no longer a concern of an individual country. It has huge global and societal implications, particularly in developing countries where the development of diabetes at an early age can lead to untoward human suffering, disability and socioeconomic cost. An internationally coordinated effort is required to improve human behaviour and lifestyle to halt the global diabetes epidemic and the development of such complications as retinopathy, nephropathy, neuropathy, cardiovascular diseases, peripheral vascular diseases and stroke. For such a formula to be successful, it is important for nurses to be proactive in their political role in ensuring that people with diabetes become expert in their condition. In so doing, healthcare systems and resources could be used more effectively to reduce real human and economic costs.

Postmenopausal women and the health consequences of obesity

The health consequences of obesity include increased risk of heart disease, hypertension, diabetes, sleep apnea, cancer, osteoarthritis, and mental health problems. Postmenopausal women have reached an age when the incidence of chronic health conditions becomes more prevalent. In addition to physical disease risks, a lifetime of ridicule and disrespect may seriously and adversely affect general and health-related quality of life. Thus, obese postmenopausal women stand at a crossroads between living the remainder of their lives in essentially good health or facing the likely onset of chronic diseases that might have been prevented. This article reviews the effects of obesity that have particular relevance for postmenopausal women.

Lysophosphatidic acid regulates blood glucose by stimulating myotube and adipocyte glucose uptake

Lysophosphatidic acid (LPA) is known to have diverse cellular effects, but although LPA is present in many biological fluids, including blood, its effects on glucose metabolism have not been elucidated. In this study, we investigated whether LPA stimulation is related to glucose regulation. LPA was found to enhance glucose uptake in a dose-dependent manner both in L6 GLUT4myc myotubes and 3T3-L1 adipocytes by triggering GLUT4 translocation to the plasma membrane. Moreover, the effect of LPA on glucose uptake was completely inhibited by pretreating both cells with LPA receptor antagonist Ki16425 and Gi inhibitor pertussis toxin. In addition, LPA increased the phosphorylation of AKT-1 with no effects on IRS-1, and LPA-induced glucose uptake was abrogated by pretreatment with the PI 3-kinase inhibitor LY294002. When low concentration of insulin and LPA were treated simultaneously, an additive effect on glucose uptake was observed in both cell types. In line with its cellular functions, LPA significantly lowered blood glucose levels in normal mice but did not affect insulin secretion. LPA also had a glucose-lowering effect in streptozotocin-treated type 1 diabetic mice. In combination, these results suggest that LPA is involved in the regulation of glucose homeostasis in muscle and adipose tissues.

Life course pathways to adult-onset diabetes

Early life conditions, such as socioeconomic status (SES) and health, have the potential to set in motion multiple and reinforcing pathways that shape both the prevalence and onset of diabetes among older adults. Using data from the Health and Retirement Study (1998-2002) for persons age 51 years and older, we investigated the core mediating mechanisms linking early life conditions with diabetes prevalence in 1998 and onset over a 4-year follow-up period, focusing on adult achievement processes and obesity as key mechanisms. We found that father's education is negatively associated with diabetes prevalence for older men and women. However, no markers of early life SES are directly associated with older men's and women's onset of diabetes, and the negative effects of adult SES on diabetes onset pertain only to women. Early life health affects the onset of diabetes among women--but not the prevalence--and no evidence of this association was found for men. We found no evidence that obesity is an important mechanism connecting either early life or adult SES with diabetes development in men or women. We speculate that early life SES may accelerate the development of diabetes at younger ages, and that the pathways linking life course SES, early life health, and diabetes are partly gender-specific and biological in nature.

Use of Insulin and Weight Gain: Optimizing Diabetes Nutrition Therapy

The prevalence of diabetes in the United States is increasing at epidemic levels, with over 20.8 million people, or approximately 7.0% of the population, affected. While diabetes is projected to increase by 165% in the next 50 years, many people with diabetes are unable to reach recommended glycemic targets. Although more intensive therapy, often incorporating insulin, is clearly required for many patients, potential side effects, such as weight gain, can deter patients from optimal therapy and undermine the efforts of registered dietitians to improve diabetes self-management. Weight gain occurs following insulin therapy for a number of reasons, including caloric retention because of improved glycemic control; excess caloric intake; decreased caloric expenditure; sedentary lifestyles; and unphysiologic action of conventional insulin formulations. However, weight gain with insulin therapy is not inevitable, and the downward spiral in diabetes management associated with weight gain can be avoided through education and careful attention to therapy regimen. Registered dietitians must be involved before and after initiation of insulin therapy to help patients avoid or minimize weight gain, maximize adherence and glycemic control, and avoid the long-term complications of diabetes.

Prevalence, awareness and control of diabetes in the Seychelles and relationship with excess body weight

Background

The evidence for a "diabesity" epidemic is accumulating worldwide but population-based data are still scarce in the African region. We assessed the prevalence, awareness and control of diabetes (DM) in the Seychelles, a rapidly developing country in the African region. We also examined the relationship between body mass index, fasting serum insulin and DM.

Methods

Examination survey in a sample representative of the entire population aged 25–64 of the Seychelles, attended by 1255 persons (participation rate of 80.2%). An oral glucose tolerance test (OGTT) was performed in individuals with fasting blood glucose between 5.6 and 6.9 mmol/l. Diabetes mellitus (DM), impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) were defined along criteria of the ADA. Prevalence estimates were standardized for age.

Results

The prevalence of DM was 11.5% and 54% of persons with DM were aware of having DM. Less than a quarter of all diabetic persons under treatment were well controlled for glycemia (HbA1c), blood pressure or LDL-cholesterol. The prevalence of IGT and IFG were respectively 10.4% and 24.2%. The prevalence of excess weight (BMI ≥ 25 kg/m²) and obesity (BMI ≥ 30 kg/m²) was respectively 60.1% and 25.0%. Half of all DM cases in the population could be attributed to excess weight.

Conclusion

We found a high prevalence of DM and pre-diabetes in a rapidly developing country in the African region. The strong association between overweight and DM emphasizes the importance of weight control measures to reduce the incidence of DM in the population. High rates of diabetic persons not aware of having DM in the population and insufficient cardiometabolic control among persons treated for DM stress the need for intensifying health care for diabetes.

Resolution of diabetes mellitus and metabolic syndrome following Roux-en-Y gastric bypass and a variant of biliopancreatic diversion in patients with morbid obesity

BACKGROUND

Obesity is associated with increased prevalence of type 2 diabetes mellitus (DM2) and metabolic syndrome and increased morbidity and mortality. Bariatric surgery results in significant and long-term weight loss. Two of the most effective and popular bariatric procedures are Roux-en-Y gastric bypass (RYGBP) and biliopancreatic diversion (BPD). The objective of this study was to investigate the effects of RYGBP and BPD-RYGBP, a variant of BPD with a lower rate of metabolic deficiencies than BPD, on DM2 and the major components of metabolic syndrome in patients with morbid obesity and DM2.

METHODS

The prospective database of our unit, from June 1994 until May 2006, was analyzed and 137 patients with DM2 were found. 26 underwent RYGBP (BMI 46.1 +/- 2.9 kg/m2) and 111 BPD-RYGBP (BMI 59.7 +/- 10.6 kg/m2). 7 of the patients were on insulin (4.90%) and 37 on oral hypoglycemic agents (25.87%). Pre- and postoperative medications, and clinical and biochemical parameters were considered in the analysis. The mean follow-up was 26.39 +/- 21.17 months.

RESULTS

Excess weight loss was approximately 70% after either procedure. DM2 resolved in 89% and 99% of the cases following RYGBP and BPD-RYGBP, respectively. 2 years after BPD-RYGBP all the patients had blood glucose < 110 mg/dl, 95% had normal cholesterol, 92% normal triglycerides and 82% normal blood pressure. The respective values following RYGBP were 66%, 33%, 78% and 44%. Uric acid decreased significantly only after BPD-RYGBP. Liver enzymes improved in both groups.

CONCLUSIONS

RYGBP and BPD-RYGBP are safe and lead to normalization of blood glucose, lipids, uric acid, liver enzymes and arterial pressure in the majority of patients, although this variant of BPD was more effective than RYGBP. We suggest that further studies should also investigate its usefulness in patients with milder degrees of obesity, DM2 and metabolic syndrome.

Adiposity, physical fitness and incident diabetes: the physical activity longitudinal study

AIMS/HYPOTHESIS

The purpose of this study was to investigate the relationships among adiposity, physical activity, physical fitness and the development of diabetes in a diverse sample of Canadians.

METHODS

The sample included 1,543 adults (709 men and 834 women) from the Canadian Physical Activity Longitudinal Study who were free of diabetes at baseline (1988). Several indicators of adiposity (BMI, waist circumference, WHR, sum of skinfold thicknesses), musculoskeletal fitness (sit-ups, push-ups, grip strength, trunk flexibility), cardiorespiratory fitness (maximal metabolic equivalents [METs]) and leisure-time physical activity levels were measured at baseline. Participants were followed until 2002-2004 for the ascertainment of new cases of diabetes.

RESULTS

The 15.5-year cumulative incidence of diabetes was 5.0% (5.2% in men, 4.9% in women). Adiposity and physical fitness, but not physical activity, were significant predictors of diabetes after adjustment for age, sex and several covariates. For each standard deviation of the indicators of adiposity, the risk of diabetes was 99-194% higher. Conversely, the risk was 70 and 61% lower for each standard deviation of maximal METs and composite musculoskeletal fitness score, respectively. Receiver operating characteristic curve analyses confirmed that neither adiposity nor physical fitness provided a superior prediction of incident diabetes.

CONCLUSIONS/INTERPRETATION

Adiposity and physical fitness were both important predictors of the development of diabetes in this cohort of Canadians.

Abdominal obesity and metabolic syndrome

Metabolic syndrome is associated with abdominal obesity, blood lipid disorders, inflammation, insulin resistance or full-blown diabetes, and increased risk of developing cardiovascular disease. Proposed criteria for identifying patients with metabolic syndrome have contributed greatly to preventive medicine, but the value of metabolic syndrome as a scientific concept remains controversial. The presence of metabolic syndrome alone cannot predict global cardiovascular disease risk. But abdominal obesity - the most prevalent manifestation of metabolic syndrome - is a marker of 'dysfunctional adipose tissue', and is of central importance in clinical diagnosis. Better risk assessment algorithms are needed to quantify diabetes and cardiovascular disease risk on a global scale.

Relationship between renal and cardiovascular changes in a murine model of glucose intolerance

Nutrition is an important variable which may affect the risk for renal disease. We previously showed that a high fructose diet in mice produced hypertension and sympathetic activation [8]. The purpose of this study was to determine if a fructose diet altered renal function. A high fructose diet for 12 weeks impaired glucose tolerance, but caused no change in body weight, blood glucose or plasma insulin. Impairment in renal function was documented by the almost two fold increase in urinary protein excretion (

CONTROL

6.6+/-0.6 vs. Fructose: 15.0+/-0.7 mmol protein/mmol creatinine; p<0.05) which was also accompanied by increases in urinary volume. The diet produced little change in renal histology, kidney weight or kidney weight/body weight ratio. Urinary excretion of angiotensin II/creatinine (

CONTROL

78.9+/-16.6 vs. Fructose: 80.5+/-14.2 pg/mmol) and renal angiotensin converting enzyme activity (

CONTROL

9.2+/-1.6 vs. Fructose: 7.6+/-1.0 ACE units) were not different between groups. There was a positive correlation between mean arterial pressure (r=0.7, p=0.01), blood pressure variability (BPV) (r=0.7, p=0.02), low frequency BPV component (r=0.677, p=0.03) and urinary protein excretion. Results show that consumption of a high fructose diet in mice had deleterious effects on renal function, which were correlated with cardiovascular changes.

Preventive Effect of Diabegon, a Polyherbal Preparation, During Progression of Diabetes Induced by High-Fructose Feeding in Rats

In the present study, the polyherbal preparation diabegon, containing 18 plant extracts with hypoglycemic activity, was evaluated for its preventive effect during progression of type 2 diabetes in high-fructose-diet-fed rats. Oral administration of diabegon (100 mg/kg body weight) delayed development of glucose intolerance for 4 weeks in comparison with the diabetic control group, and the effect of diabegon was compared to that of the standard insulin sensitizer drug rosiglitazone. Diabegon treatment also ameliorated the elevation of glycosylated haemoglobin, liver glycogen content, plasma insulin, homeostasis model assessment, free fatty acids, triglycerides, total cholesterol, LDL-cholesterol, and VLDL-cholesterol, whereas it increased HDL-cholesterol after 56 days of treatment (P<0.05). The mechanism of action by which diabegon attenuates insulin resistance and dyslipidemia may be through induction of peroxisome proliferator-activated receptor-gamma and lipoprotein lipase activity in peripheral tissues (muscles). Moreover, diabegon administration for 56 days also produced no alteration in liver and kidney function tests, which seems to indicate its non-toxicity during treatment. Our present results suggest that diabegon may be included in diabetes mellitus treatment regimens, as a drug with good antidiabetic actions but no toxic manifestations.

Beneficial associations of physical activity with 2-h but not fasting blood glucose in Australian adults: the AusDiab study

OBJECTIVE

We examined the associations of physical activity with fasting plasma glucose (FPG) and with 2-h postload plasma glucose (2-h PG) in men and women with low, moderate, and high waist circumference.

RESEARCH DESIGN AND METHODS

The Australian Diabetes, Obesity and Lifestyle (AusDiab) study provided data on a population-based cross-sectional sample of 4,108 men and 5,106 women aged >or=25 years without known diabetes or health conditions that could affect physical activity. FPG and 2-h PG were obtained from an oral glucose tolerance test. Self-reported physical activity level was defined according to the current public health guidelines as active (>or=150 min/week across five or more sessions) or inactive (<150 min/week and/or less than five sessions). Sex-specific quintiles of physical activity time were used to ascertain dose response.

RESULTS

Being physically active and total physical activity time were independently and negatively associated with 2-h PG. When physical activity level was considered within each waist circumference category, 2-h PG was significantly lower in active high-waist circumference women (beta -0.30 [95% CI -0.59 to -0.01], P = 0.044) and active low-waist circumference men (beta -0.25 [-0.49 to -0.02], P = 0.036) compared with their inactive counterparts. Considered across physical activity and waist circumference categories, 2-h PG levels were not significantly different between active moderate-waist circumference participants and active low-waist circumference participants. Associations between physical activity and FPG were nonsignificant.

CONCLUSIONS

There are important differences between 2-h PG and FPG related to physical activity. It appears that 2-h PG is more sensitive to the beneficial effects of physical activity, and these benefits occur across the waist circumference spectrum.

AMP-activated protein kinase: Role in metabolism and therapeutic implications

AMP-activated protein kinase (AMPK) is an enzyme that works as a fuel gauge which becomes activated in situations of energy consumption. AMPK functions to restore cellular ATP levels by modifying diverse metabolic and cellular pathways. In the skeletal muscle, AMPK is activated during exercise and is involved in contraction-stimulated glucose transport and fatty acid oxidation. In the heart, AMPK activity increases during ischaemia and functions to sustain ATP, cardiac function and myocardial viability. In the liver, AMPK inhibits the production of glucose, cholesterol and triglycerides and stimulates fatty acid oxidation. Recent studies have shown that AMPK is involved in the mechanism of action of metformin and thiazolidinediones, and the adipocytokines leptin and adiponectin. These data, along with evidence that pharmacological activation of AMPK in vivo improves blood glucose homeostasis, cholesterol concentrations and blood pressure in insulin-resistant rodents, make this enzyme an attractive pharmacological target for the treatment of type 2 diabetes, ischaemic heart disease and other metabolic diseases.

Body fat distribution and risk of type 2 diabetes in the general population: are there differences between men and women? The MONICA/KORA Augsburg cohort study

BACKGROUND

It remains controversial whether body mass index (BMI), waist circumference (WC), or waist-hip ratio (WHR) is a better risk predictor of type 2 diabetes.

OBJECTIVE

The objective was to examine the sex-specific relevance of WC, WHR, and BMI to the development of type 2 diabetes.

DESIGN

The prospective population-based cohort study was based on 3055 men and 2957 women aged 35-74 y who participated in the second (1989-1990) or third (1994-1995) MONICA (Monitoring Trends and Determinants on Cardiovascular Diseases) Augsburg survey. The subjects were free of diabetes at baseline. Hazard ratios (HRs) were estimated from Cox proportional hazards models.

RESULTS

During a mean follow-up of 9.2 y, 243 cases of incident type 2 diabetes occurred in men and 158 occurred in women. Multivariable-adjusted HRs across quartiles of BMI were 1.0, 1.37, 2.08, and 4.15 in men and 1.0, 3.77, 4.95, and 10.58 in women; those of WC were 1.0, 1.15, 1.57, and 3.40 in men and 1.0, 3.21, 3.98, and 10.70 in women; those of WHR were 1.0, 1.14, 1.80, and 2.84 in men and 1.0, 0.82, 2.06, and 3.51 in women. In joint analyses, the highest risk was observed in men and women with a high BMI in combination with a high WC and a high WHR.

CONCLUSIONS

Both overall and abdominal adiposity were strongly related to the development of type 2 diabetes. Because there was an additive effect of overall and abdominal obesity on risk prediction, WC should be measured in addition to BMI to assess the risk of type 2 diabetes in both sexes.

Moderately overweight and obese patients in general practice: a population based survey

Background

Obesity is a main threat to public health in the Western world and is associated with diseases such as diabetes mellitus and coronary heart diseases. Up to now a minority of research studied the relation between obesity and the use of primary health care. In the Netherlands the general practitioner (GP) is the main primary health care provider. The objective of this article is to evaluate GP consultation and prescription of drugs in moderate and severely overweight (obese) persons in the Netherlands.

Methods

Data were used from a representative survey of morbidity in Dutch general practice in 2001. Our study sample consisted of 8,944 adult respondents (18+ years) who participated in an extensive health interview. Interview data were linked to morbidity and prescription registration data from 95 general practices where respondents were listed. Body mass index (BMI) was calculated using self-reported height and weight. Analyses were controlled for clustering within practices as well as for socio-demographic and life style characteristics.

Results

Obesity (BMI ≥ 30 kg/m2) was observed in 8.9% of men and 12.4% of women; for moderate overweight (BMI 25-<30 kg/m2) these percentages were 42.2% and 30.4% respectively. Obese men and women were more likely to consult their GP than persons without overweight. This especially holds for diseases of the endocrine system, the cardiovascular system, the musculoskeletal system, the gastro-intestinal system, and skin problems. Related to this, obese men and women were more likely to receive drugs for the cardiovascular system, the musculoskeletal system, alimentary tract and metabolism (including, for example, antidiabetics), and dermatologicals, but also antibiotics and drugs for the respiratory system. For moderately overweight men and women (BMI 25-<30 kg/m2) smaller but significant differences were found for diseases of the endocrine system, the cardiovascular system, and the musculoskeletal system.

Conclusion

Obesity increases the workload of Dutch general practitioners and the use of prescribed medication. The current increase in the prevalence of obesity will further increase the use of health care and related costs. Since a large majority of Dutch persons visit their GP over the course of one year, GPs' potential role in effective prevention strategies cannot be denied.

Body cell mass measured by total body potassium in normal-weight and obese men and women

OBJECTIVE

Total body potassium (TBK) concentration is linearly correlated with the size of the body cell mass (BCM). The aim of this study was to compare BCM in normal-weight and obese individuals.

METHODS

271 individuals (207 males, 64 females), 20 to 67 years of age, participated in this study. Subjects were separated by body mass index (BMI): BMI < 25 kg/m(2) (BMI-L) and BMI > 25 kg/m(2) (BMI-H). (40)K was assessed using a whole-body counter and BCM was calculated.

RESULTS

BCM and TBK were significantly greater in men, with a trend to be greater in women in BMI-H compared to men in BMI-L. TBK/body weight was significantly lower, while TBK/height was significantly greater for men and women in BMI-H compared to men and women in BMI-L. Fat-free mass (FFM) was significantly greater for men in BMI-H, with no significant differences in FFM between the two groups of women.

CONCLUSIONS

The healthy obese subjects in the present study had a greater BCM than the non-obese subjects. These results indicate that it is important to assess BCM in obese individuals because it could influence the type of weight loss regimen that will be used in order to preserve BCM.

The epidemiology of low-grade chronic systemic inflammation and type 2 diabetes

The fattening of the human species and the accompanying emergence of the metabolic syndrome and of type 2 diabetes as remarkably frequent clinical entities are among the major epidemiologic events of our time. Control of the diabetes epidemic requires a greater understanding of the pathophysiologic processes underlying these phenomena. Many epidemiologic studies have now shown associations between inflammation markers and diabetes, with the most consistent being for leukocytes and the strongest being for C-reactive protein. Consistent protective associations have also been reported for adiponectin, an adipocyte secretory protein with antiinflammatory actions. Although great variability is seen between reported associations, as a whole these studies suggest a role for inflammation linked to obesity. The variability reported is in part due to differences in model adjustment, in how diabetes was ascertained, and in the different means used to operationalize the concept of low-grade chronic systemic inflammation. It is also due, in part, to sample characterization, as findings are heterogeneous across some subgroups, such as those defined by smoking. Consistent with their association with type 2 diabetes, inflammation markers have also be shown to predict conditions present in the prediabetes state such as weight gain, hypertension, gestational diabetes, and decline in insulin sensitivity.

High prevalence of obesity and diabetes mellitus in Konya, a central Anatolian city in Turkey

INTRODUCTION

The objective of this study was to determine the prevalence of overweight, obesity, impaired fasting glucose, diabetes and the relationship between adiposity and carbohydrate metabolism, by age and gender in Konya, a city in central Anatolia.

METHODS

A cross-sectional population based survey was performed. One month before the field survey a media campaign was started in each district by local municipalities. Ten percent of the target population age 20 and over were invited to participate and the participation rate was 82.1%. Twelve thousand eight hundred and sixty-six inhabitants (7000 women and 5866 men, mean age 46.7+/-15.9 years) were evaluated for height and body weight between May and September of 2001. Two thousand eight hundred and thirty consecutive subjects (1788 women and 1042 men, mean age 48.2+/-15.7 years) were tested for fasting blood glucose in addition to an anthropometric evaluation.

RESULTS

The crude IFG rate was 24% (27.1% in women and 18.5% in men) and the diabetes rate 8.4% (8% in women and 9.1% in men). The survey identified previously undiagnosed diabetes in 3.7% (4.3% of women and 2.9% of men). The prevalence of diabetes (p=0.0005) and obesity (p=0.0005) increased with age. Obese men and women had a higher risk of being diabetic than their normal weight counterparts (OR, 2.05; CI 95%, 1.13-3.71; p=0.0186 and OR, 2.53; CI 95%, 1.57-4.07; p=0.0001, respectively). Overall, the overweight rate was 34.2% (33.5% of women and 36.3% of men) and the obesity rate was 23.7% (32.4% of women and 14.1% of men) (n=12,866). Women had a significantly higher risk of being obese than men (OR, 2.84; CI 95%, 2.62-3.08; p=0.0005). The diabesity rate was 3.4% (4.1% in women and 2.1% in men).

CONCLUSION

Carbohydrate intolerance and adiposity are highly prevalent in Konya, and the two conditions are positively correlated with each other, by age and gender.

The effects of orlistat in patients with diabetes: improvement in glycaemic control and weight loss

OBJECTIVE

In addition to direct weight reduction, there may be other benefits of obesity treatment including improved insulin sensitivity. The purpose of this study was to characterise concomitant diabetes drug use and the related costs in patients with diabetes treated with orlistat (Xenical) in the first 6 months of treatment.

METHODS

One hundred overweight patients with diabetes and a body mass index (BMI) > or = 28 kg/m2 were enrolled in a structured UK hospital-based weight management clinic and treated with orlistat plus behavioural interventions. Among other measures, weight, glucose control (HbA1c) and drug treatment were recorded. Subjects were followed-up for a maximum of 24 months at intervals of 1-3 months, with a maximum treatment period of 24 months.

RESULTS

The majority of subjects (91%) had type 2 diabetes. They had a mean age of 55 years and 55% were women. For patients followed up at 6 months, their mean BMI at baseline was 39.5 kg/m2 with a mean HbA1c of 7.6%. The mean weight loss at 6 months was 7.1 kg (p < 0.001). Despite a significant average absolute HbA1c reduction of 0.62% (p < 0.001), the most notable gains were made by those with the highest baseline HbA1c values (a mean relative reduction of 20% for those above the 75th percentile). There were 50 patients treated with insulin at baseline and 47 at 6 months. Of those treated with insulin, the mean dose was 130 units at baseline and 90 units at 6 months (p < 0.001). Twenty patients (44.4%) initially treated with oral hypoglycaemic agents alone reduced their dose after 6 months (not significant). Despite marked improvement in insulin sensitivity (baseline mean, 1.24 units/kg; 6 month mean, 0.90 units/kg [p < 0.001]) there was no correlation with BMI change. The average cost of diabetes treatment at baseline was pound 1.16 per day and pound 0.83 at 6 months (p < 0.001). Age was the only independent predictor for insulin dose reduction.

CONCLUSIONS

Orlistat appears to reduce the need for concomitant diabetes medication irrespective of weight loss, a reduction that is likely to represent a large cost offset for orlistat treatment.

Natural anti-diabetic compound 1,2,3,4,6-penta-O-galloyl-d-glucopyranose binds to insulin receptor and activates insulin-mediated glucose transport signaling pathway

Insulin mimetics from natural sources are potential therapeutics that can act alone or supplement insulin and other anti-diabetic drugs in the prevention and treatment of diabetes. We recently reported the insulin-like glucose transport stimulatory activity of tannic acid (TA) in 3T3-L1 adipocytes. In this study, we find that chemically synthesized 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranose (beta-PGG), one of the components of TA, as well as its natural anomer alpha-PGG possess activity. Mechanistic studies in adipocytes with alpha-PGG, the more potent of the two anomers, reveal that inhibitors that block the insulin-mediated glucose transport, including one that inhibits the insulin receptor (IR), also completely abolish the glucose transport activated by alpha-PGG. In addition, alpha-PGG induces phosphorylation of the IR and Akt, activates PI 3-kinase, and stimulates membrane translocation of GLUT 4. Receptor binding studies indicate that alpha-PGG binds to the IR and affects the binding between insulin and IR by reducing the maximum binding of insulin to IR without significantly altering the binding affinity of insulin to IR. Western blotting analysis of the products of a cross-linking reaction suggests that alpha-PGG may bind to IR at a site located on the alpha-subunit of the receptor. Animal studies demonstrate that PGG reduces blood glucose levels and improves glucose tolerance in diabetic and obese animals. Our results suggest that PGG may serve as a model for the development of new types of anti-diabetic and anti-metabolic syndrome therapeutics.

Searching QTL by gene expression: analysis of diabesity

Background

Recent developments in sequence databases provide the opportunity to relate the expression pattern of genes to their genomic position, thus creating a transcriptome map. Quantitative trait loci (QTL) are phenotypically-defined chromosomal regions that contribute to allelically variant biological traits, and by overlaying QTL on the transcriptome, the search for candidate genes becomes extremely focused.

Results

We used our novel data mining tool, ExQuest, to select genes within known diabesity QTL showing enriched expression in primary diabesity affected tissues. We then quantified transcripts in adipose, pancreas, and liver tissue from Tally Ho mice, a multigenic model for Type II diabetes (T2D), and from diabesity-resistant C57BL/6J controls. Analysis of the resulting quantitative PCR data using the Global Pattern Recognition analytical algorithm identified a number of genes whose expression is altered, and thus are novel candidates for diabesity QTL and/or pathways associated with diabesity.

Conclusion

Transcription-based data mining of genes in QTL-limited intervals followed by efficient quantitative PCR methods is an effective strategy for identifying genes that may contribute to complex pathophysiological processes.

Fructose, insulin resistance, and metabolic dyslipidemia

Obesity and type 2 diabetes are occurring at epidemic rates in the United States and many parts of the world. The "obesity epidemic" appears to have emerged largely from changes in our diet and reduced physical activity. An important but not well-appreciated dietary change has been the substantial increase in the amount of dietary fructose consumption from high intake of sucrose and high fructose corn syrup, a common sweetener used in the food industry. A high flux of fructose to the liver, the main organ capable of metabolizing this simple carbohydrate, perturbs glucose metabolism and glucose uptake pathways, and leads to a significantly enhanced rate of de novo lipogenesis and triglyceride (TG) synthesis, driven by the high flux of glycerol and acyl portions of TG molecules from fructose catabolism. These metabolic disturbances appear to underlie the induction of insulin resistance commonly observed with high fructose feeding in both humans and animal models. Fructose-induced insulin resistant states are commonly characterized by a profound metabolic dyslipidemia, which appears to result from hepatic and intestinal overproduction of atherogenic lipoprotein particles. Thus, emerging evidence from recent epidemiological and biochemical studies clearly suggests that the high dietary intake of fructose has rapidly become an important causative factor in the development of the metabolic syndrome. There is an urgent need for increased public awareness of the risks associated with high fructose consumption and greater efforts should be made to curb the supplementation of packaged foods with high fructose additives. The present review will discuss the trends in fructose consumption, the metabolic consequences of increased fructose intake, and the molecular mechanisms leading to fructose-induced lipogenesis, insulin resistance and metabolic dyslipidemia.

Tannic acid stimulates glucose transport and inhibits adipocyte differentiation in 3T3-L1 cells

Obesity is a major risk factor for Syndrome X and type II diabetes (T2D). However, most antidiabetic drugs that are hypoglycemic also promote weight gain, thus alleviating one symptom of T2D while aggravating a major risk factor that leads to T2D. Adipogenesis, the differentiation and proliferation of adipocytes, is a major mechanism leading to weight gain and obesity. It is highly desirable to develop pharmaceuticals and treatments for T2D that reduce blood glucose levels without inducing adipogenesis in patients. Previously, we reported that an extract from Lagerstroemia speciosa L. (banaba) possessed activities that both stimulated glucose transport and inhibited adipocyte differentiation in 3T3-L1 cells. Using glucose uptake assays and Western/Northern blot analyses as major tools and 3T3-L1 cells as a model, we showed that the banaba extract (BE) with tannin removed was devoid of the 2 activities, and tannic acid (TA), a major component of tannins, had the same 2 activities as BE. Inhibitors known to abolish insulin-induced glucose transport also blocked TA-induced glucose transport. We further detected that TA induced phosphorylation of the insulin receptor (IR) and Akt, as well as translocation of glucose transporter 4 (GLUT 4), the protein factors involved in the signaling pathway of insulin-mediated glucose transport. We also demonstrated that TA inhibited the expression of key genes for adipogenesis. Differences between samples with or without TA in all of the quantitative assays were significant (P < 0.05). These results suggest that TA may be useful for the prevention and treatment of T2D and its associated obesity. TA may have the potential to become the lead compound in the development of new types of antidiabetic pharmaceuticals that are able to reduce blood glucose levels without increasing adiposity.

The M16 mouse: an outbred animal model of early onset polygenic obesity and diabesity

OBJECTIVE

To characterize the phenotypic consequences of long-term selective breeding for rapid weight gain, with an emphasis on obesity and obesity-induced diabetes (diabesity).

RESEARCH METHODS AND PROCEDURES

M16 is the result of long-term selection for 3- to 6-week weight gain from an ICR base population. Experiment 1 characterized males from both lines for body weights (3, 6, and 8 weeks), feed (4 to 8 weeks) and H(2)O (6 to 8 weeks) consumption, and heat loss, body composition, and levels of several plasma proteins at 8 weeks of age. Experiment 2 characterized differences between lines for both sexes at three ages (6, 8, and 16 weeks) and fed two diets (high and normal fat). Body weight, composition, blood glucose, and plasma insulin and leptin levels were evaluated after an 8-hour fast.

RESULTS

At all ages measured, M16 mice were heavier, fatter, hyperphagic, hyperinsulinemic, and hyperleptinemic relative to ICR. M16 males and females were hyperglycemic relative to ICR, with 56% and 22% higher fasted blood glucose levels at 8 weeks of age.

DISCUSSION

M16 mice represent an outbred animal model to facilitate gene discovery and pathway regulation controlling early onset polygenic obesity and type 2 diabetic phenotypes. Phenotypes prevalent in the M16 model, with obesity and diabesity exhibited at a young age, closely mirror current trends in human populations.

Weight loss: the treatment of choice for knee osteoarthritis? A randomized trial

OBJECTIVE

We wanted to assess the effect of rapid diet-induced weight loss on the function of obese, knee osteoarthritis (OA) patients.

METHODS

Eighty patients with knee OA, 89% women (n=71), were recruited. Mean (SD) body-mass index (BMI) was 35.9 (5.1) kg/m(2) and age 62.6 (11.1) years. Patients were randomized to either a low-energy diet (LED 3.4MJ/day), or a control diet (5MJ/day). The LED group had weekly dietary sessions, whereas the control group was given a booklet describing weight loss practices. Changes in body weight and body composition were examined as independent predictors of changes in knee OA symptoms. Symptoms were monitored by the Western Ontario and McMaster Universities' (WOMAC) OA index.

RESULTS

The LED and control group lost a mean (SE) of 11.1 (0.6)% and 4.3 (0.6)%, respectively, with a mean difference being 6.8% (95% confidence interval (CI): 5.5 to 8.1%; P<0.0001). The decrease in body fat percent was higher in the LED group, 2.2% (1.5 to 3.0%; P<0.0001). The total WOMAC index improved in the LED group (P<0.0001), but not in the control group (P=0.12), mean difference: -219.3mm (-369.2 to -69.4mm; P=0.005). The 'Number Needed to Treat (NNT)' to ensure an improvement in WOMAC>/=50% was 3.4 (2.1 to 8.8) patients. Changes in total WOMAC index were best predicted by the reduction of body fat percent, with a 9.4% (4.8 to 13.9%) improvement in WOMAC for each percent of body fat reduced (P=0.0005).

CONCLUSIONS

In our patients with knee OA, a weight reduction of 10% improved function by 28%. LED might be of advantage to control diet because of the rapidity of weight loss and a more significant loss of body fat.

Diabesity

Weight reduction has been shown to improve glycemic control and cardiovascular risk factors associated with insulin resistance in obese individuals with type 2 diabetes mellitus. Therapeutic options for these patients include promoting weight loss (non-pharmacologic and pharmacologic treatment) and improving glycemic control, as well as treating common associated risk factors such as arterial hypertension and dyslipidemias. This article provides an overview of anti-obesity drugs used in the treatment of obese individuals with type 2 diabetes. The most widely investigated drugs, sibutramine and orlistat, result in modest, clinically worthwhile weight loss, with demonstrable improvements in many co-morbidities, among them, type 2 diabetes. Clinical trials with these anti-obesity medications in cohorts of obese diabetic patients have been reviewed as well as cathecolaminergic agents (diethylpropion [amfepramone], fenproporex, mazindol, ephedrine-caffeine combination), serotoninergic drugs (fenfluramine, dexfenfluramine, fluoxetine), and other drugs that have some action on weight loss (the antidiabetic agent metformin, anti-epileptic agents topiramate and zonisamide, and the antidepressive bupropion [amfebutamone]). These trials show variable benefits in terms of effects on glucose profiles.

Postprandial hyperglycaemia in type 2 diabetes: pathophysiological aspects, teleological notions and flags for clinical practice

Type 2 diabetes subjects carry an excess risk for micro- and macrovascular disease and a higher cardiovascular morbidity and mortality rate. The beneficial impact of tight glycaemic control-evidenced by the integrated marker of fasting glucose and postprandial glucose values, the HbA1c-for the prevention of microvascular complications is definitely confirmed. Over the past few years, several studies have identified postprandial hyperglycaemia as a better predictor of cardiovascular or even of all-cause mortality, as well as an independent risk factor for atherosclerosis. The continuous glucose monitoring could offer a rationale means for the detection of postprandial hyperglycaemia and ultimately for its effective management. Advances in technology keep a promise for a reliable, convenient and closer to the idea of the artificial endocrine pancreas glucose sensor. Subcutaneous glucose levels charted by one of the new sensors were found to be well correlated with venous glucose measurements. Intervention for a healthy lifestyle is frequently hampered by patients' poor compliance. The availability of diverse antidiabetic agents provides options for targeting the glycaemic goal and a choice more fitted to the particularized pathophysiology of each individual subject. Drugs targeting postprandial glycaemia may prove to represent the 'sine qua non' for the 'return' of postprandial glucose values at a 'non-deleterious' threshold, either as monotherapy for the early stages of the disease or as combination therapy later in the progression of diabetes.

Genetics of the APM1 locus and its contribution to type 2 diabetes susceptibility in French Caucasians

We have carried out a detailed reexamination of the genetics of the APM1 locus and its contribution to the genetic basis of type 2 diabetes susceptibility in the French Caucasian population. The G allele of single nucleotide polymorphism -11426 in the APM1 promoter showed modest association with type 2 diabetes (odds ratio 1.44 [95% CI 1.04-1.98]; P = 0.03), providing corroborative evidence that single nucleotide polymorphisms in the APM1 promoter region contribute to the genetic risk of type 2 diabetes. A "sliding window" analysis identified haplotypes 1-1-1, 1-1-1-1, and 1-1-1-1-1 as being strongly protective against type 2 diabetes (P </= 0.0001). Evidence is presented that the APM1 gene is a locus of low linkage disequilibrium, high haplotype diversity, and high recombination. We were unable to obtain data to support the hypothesis that genetic variation in the APM1 gene is a major contributor to the type 2 diabetes linkage result at chromosome 3q27. Finally, in families with early-onset type 2 diabetes, we obtained suggestive evidence of a linkage peak for serum adiponectin levels (logarithm of odds = 2.1) that closely matched the position of the type 2 diabetes linkage peak. This result indicated that the type 2 diabetes susceptibility locus at 3q27 influences both genetic predisposition to type 2 diabetes and serum adiponectin levels in patients with type 2 diabetes.

Macrovascular complications of metabolic syndrome: an early intervention is imperative

The metabolic syndrome is a widespread clinical condition and an important cluster of atherothrombotic disease risk factors. The inclusion of this syndrome in the recently published Adult Treatment Panel III (ATP III) guidelines focused the attention of the physicians on this entity. Abdominal obesity, PPAR modulation, insulin resistance (with or without glucose intolerance), atherogenic dyslipidemia, elevated blood pressure, prothrombotic and proinflammatory states are the principal factors of this multifaceted syndrome. There are two major pathways of metabolic syndrome progress: (1) With preserved pancreatic beta cells function and insulin hypersecretion, which can recompense for insulin resistance. This pathway leads mostly to the macrovascular complications of metabolic syndrome. (2) With substantial injure of pancreatic beta cells leading to gradually reduced insulin secretion and to hyperglycemia (e.g. overt type 2 diabetes). This pathway leads to both microvascular and macrovascular complications. Because macrovascular complications of insulin resistance state precede the onset of hyperglycemia, early intervention in patients with metabolic syndrome is particularly important. Since central obesity (accompanied by insulin resistance even in the absence of hyperglycemia) is the key factor leading to development of metabolic syndrome and its future macrovascular complications, we assume that next logical step is the recognition of central obesity itself as a major risk factor for cardiovascular diseases.

Increased 24-h energy expenditure in type 2 diabetes

OBJECTIVE

The aim of this study was to determine whether overweight and obese individuals with type 2 diabetes have higher basal and 24-h energy expenditure compared with healthy control subjects before and after adjustment for body composition, spontaneous physical activity (SPA), sex, and age.

RESEARCH DESIGN AND METHODS

Data from 31 subjects with type 2 diabetes and 61 nondiabetic control subjects were analyzed. The 24-h energy expenditure, basal metabolic rate (BMR), and sleeping energy expenditure (EEsleep) between 1:00 a.m. and 6:00 a.m. were measured in whole-body respiratory chambers. Body composition was assessed by dual-energy X-ray absorptiometry (DXA).

RESULTS

No significant differences in unadjusted EEsleep, BMR, and 24-h energy expenditure were observed between the type 2 diabetic group and the control group. After adjustment for fat-free mass (FFM), fat mass, SPA, sex, and age, EEsleep and BMR were, respectively, 7.7 and 6.9% higher in the type 2 diabetic group compared with the control group. This was equivalent to 144 +/- 40 kcal/day (P = 0.001) and 139 +/- 61 kcal/day (P = 0.026), respectively. Adjusted 24-h energy expenditure was 6.5% higher in the type 2 diabetic group compared with the nondiabetic control subjects (2,679 +/- 37 vs. 2,515 +/- 23 kcal/day, P = 0.002). In multiple regression analyses, FFM, fat mass, SPA, and diabetes status were all significant determinants of EEsleep and 24-h energy expenditure, explaining 83 and 81% of the variation, respectively.

CONCLUSIONS

This study confirms reports in Pima Indians that basal and 24-h energy expenditure adjusted for body composition, SPA, sex, and age are higher in individuals with type 2 diabetes compared with nondiabetic control subjects and may be even more pronounced in Caucasians.

Glycemic index, glycemic load, and dietary fiber intake and incidence of type 2 diabetes in younger and middle-aged women

BACKGROUND

Increasing evidence suggests an important role of carbohydrate quality in the development of type 2 diabetes.

OBJECTIVE

Our objective was to prospectively examine the association between glycemic index, glycemic load, and dietary fiber and the risk of type 2 diabetes in a large cohort of young women.

DESIGN

In 1991, 91249 women completed a semiquantitative food-frequency questionnaire that assessed dietary intake. The women were followed for 8 y for the development of incident type 2 diabetes, and dietary information was updated in 1995.

RESULTS

We identified 741 incident cases of confirmed type 2 diabetes during 8 y (716 300 person-years) of follow-up. After adjustment for age, body mass index, family history of diabetes, and other potential confounders, glycemic index was significantly associated with an increased risk of diabetes (multivariate relative risks for quintiles 1-5, respectively: 1, 1.15, 1.07, 1.27, and 1.59; 95% CI: 1.21, 2.10; P for trend = 0.001). Conversely, cereal fiber intake was associated with a decreased risk of diabetes (multivariate relative risks for quintiles 1-5, respectively: 1, 0.85, 0.87, 0.82, and 0.64; 95% CI: 0.48, 0.86; P for trend = 0.004). Glycemic load was not significantly associated with risk in the overall cohort (multivariate relative risks for quintiles 1-5, respectively: 1, 1.31, 1.20, 1.14, and 1.33; 95% CI: 0.92, 1.91; P for trend = 0.21).

CONCLUSIONS

A diet high in rapidly absorbed carbohydrates and low in cereal fiber is associated with an increased risk of type 2 diabetes.

Diabesity: an inflammatory metabolic condition

Diabesity, that is to say, obesity-dependent diabetes, has emerged as a major public health problem. Though diabesity is basically explained by insulin resistance and pancreatic beta cell dysfunction, new paradigms have evolved to explain these alterations in the context of the modern epidemics of obesity and diabetes. Among these, the association of inflammation with obesity is an important component of the common soil from which diabetes and cardiovascular diseases (CVD) derive. This Review presents our epidemiological findings, based primarily on the ARIC Study, in the context of the other epidemiological studies supporting the inflammatory nature of diabetes, CVD and the metabolic syndrome. We also review the characteristics of the innate immune system, including the molecular interface of innate immunity with metabolism, components of which are responsible for the presence of a state of mild, chronic and systemic inflammation related to diabesity. Finally, we present obesity as an inflammatory condition, obesitis, and propose a conceptual framework that integrates the epidemiological findings with new provocative basic science results.

Obesity, glucose intolerance and diabetes and their links to cardiovascular disease. Implications for laboratory medicine

This article provides an overview of the role of metabolite toxicity, low-grade inflammation and disturbed cellular signaling in obesity, glucose intolerance and diabetes. It also highlights links between this continuum of deteriorating glucose tolerance and atherosclerosis. Obesity, diabetes mellitus, and cardiovascular disease are all related to diet and to the level of physical activity. They have reached epidemic proportions worldwide. Glucose intolerance and diabetes increase the risk of atherosclerotic events. Moreover, obesity, and glucose intolerance or diabetes, are components of the metabolic syndrome, which also imparts an increased cardiovascular risk. There is increasing recognition that common mechanisms contribute to diabetes and cardiovascular disease. Following increased calorie intake and/or decreased physical activity, fuel metabolism generates excess of 'toxic' metabolites, particularly glucose and fatty acids. Homeostasis is affected by the endocrine output from the adipose tissue. Reactive oxygen species are generated, creating oxidative stress, which exerts major effects on signaling pathways, further affecting cellular metabolism and triggering low-grade inflammatory reaction. This perspective on the diabetic syndrome has been reflected in the approach to its treatment, which integrates maintenance of glycemic control with primary and secondary cardiovascular prevention. Laboratory medicine should support diabetes care with an integrated package of tests which, in addition to glycemic control, enable assessment and monitoring of the risk of microvascular complications as well as cardiovascular disease.

Dietary, evolutionary, and modernizing influences on the prevalence of type 2 diabetes

An evolutionary perspective is used to elucidate the etiology of the current epidemic of type 2 diabetes estimated at 151 million people. Our primate legacy, fossil hominid, and hunting-gathering lifestyles selected for adaptive metabolically thrifty genotypes and phenotypes are rendered deleterious through modern lifestyles that increase energy input and reduce output. The processes of modernization or globalization include the availability and abundance of calorically dense/low-fiber/high-glycemic foods and the adoption of sedentary Western lifestyles, leading to obesity among both children and adults in developed and developing countries. These trends are projected to continue for a number of decades.

Processed meat intake and incidence of Type 2 diabetes in younger and middle-aged women

AIM/HYPOTHESIS

The aim of this study was to investigate the association between processed and other meat intake and incidence of Type 2 diabetes in a large cohort of women.

METHODS

Incident cases of Type 2 diabetes were identified during 8 years of follow-up in a prospective cohort study of 91246 U.S. women aged 26 to 46 years and being free of diabetes and other major chronic diseases at baseline in 1991.

RESULTS

We identified 741 incident cases of confirmed Type 2 diabetes during 716276 person-years of follow-up. The relative risk adjusted for potential non-dietary confounders was 1.91 (95% CI: 1.42-2.57) in women consuming processed meat five times or more a week compared with those consuming processed meat less than once a week ( p<0.001 for trend). Further adjustment for intakes of magnesium, cereal fibre, glycaemic index, and caffeine or for a Western dietary pattern did not appreciably change the results and associations remained strong after further adjustment for fatty acid and cholesterol intake. Frequent consumption of bacon, hot dogs, and sausage was each associated with an increased risk of diabetes. While total red meat (beef or lamb as main dish, pork as main dish, hamburger, beef, pork or lamb as sandwich or mixed dish) intake was associated with an increased risk of diabetes, this association was attenuated after adjustment for magnesium, cereal fiber, glycaemic index, and caffeine (relative risk: 1.44; 95% CI: 0.92-2.24).

CONCLUSION/INTERPRETATION

Our data suggest that diets high in processed meats could increase the risk for developing Type 2 diabetes.

Roles of 5'-AMP-activated protein kinase (AMPK) in mammalian glucose homoeostasis

AMPK (5'-AMP-activated protein kinase) is emerging as a metabolic master switch, by which cells in both mammals and lower organisms sense and decode changes in energy status. Changes in AMPK activity have been shown to regulate glucose transport in muscle and glucose production by the liver. Moreover, AMPK appears to be a key regulator of at least one transcription factor linked to a monogenic form of diabetes mellitus. As a result, considerable efforts are now under way to explore the usefulness of AMPK as a therapeutic target for other forms of this disease. Here we review this topic, and discuss new findings which suggest that AMPK may play roles in regulating insulin release and the survival of pancreatic islet beta-cells, and nutrient sensing by the brain.

Bitter melon (Momordica charantia) reduces adiposity, lowers serum insulin and normalizes glucose tolerance in rats fed a high fat diet

Bitter melon (BM) is known for its hypoglycemic effect but its effect on rats fed a hyperinsulinemic high fat diet has not been examined. In a dose-response (0.375, 0.75 and 1.5%) study, oral glucose tolerance was improved in rats fed a high fat (HF; 30%) diet supplemented with freeze-dried BM juice at a dose of 0.75% or higher (P < 0.05). At the highest dose, BM-supplemented rats had lower energy efficiency (P < 0.05) and tended (P = 0.10) to have less visceral fat mass. In a subsequent experiment, rats habitually fed a HF diet either continued to consume the diet or were switched to a HF+BM, low fat (LF; 7%) or LF+BM diet for 7 wk. BM was added at 0.75%. Final body weight and visceral fat mass of the two last-mentioned groups were similar to those of rats fed a LF diet for the entire duration. Rats switched to the HF+BM diet gained less weight and had less visceral fat than those fed the HF diet (P < 0.05). The addition of BM did not change apparent fat absorption. BM supplementation to the HF diet improved insulin resistance, lowered serum insulin and leptin but raised serum free fatty acid concentration (P < 0.05). This study reveals for the first time that BM reduces adiposity in rats fed a HF diet. BM appears to have multiple influences on glucose and lipid metabolism that strongly counteract the untoward effects of a high fat diet.

Metabolic syndrome and type 2 diabetes mellitus: focus on peroxisome proliferator activated receptors (PPAR)

The metabolic syndrome is a highly prevalent clinical entity. The recent Adult Treatment Panel (ATP III) guidelines have called specific attention to the importance of targeting the cardiovascular risk factors of the metabolic syndrome as a method of risk reduction therapy. The main factors characteristic of this syndrome are abdominal obesity, atherogenic dyslipidemia, elevated blood pressure, insulin resistance (with or without glucose intolerance), prothrombotic and proinflammatory states. An insulin resistance following nuclear peroxisome proliferator activated receptors (PPAR) deactivation (mainly obesity-related) is the key phase of metabolic syndrome initiation. Afterwards, there are 2 principal pathways of metabolic syndrome development: 1) with preserved pancreatic beta cells function and insulin hypersecretion which can compensate for insulin resistance. This pathway leads mainly to the macrovascular complications of metabolic syndrome; 2) with massive damage of pancreatic beta cells leading to progressively decrease of insulin secretion and to hyperglycemia (e.g. overt type 2 diabetes). This pathway leads to both microvascular and macrovascular complications. We suggest that a PPAR-based appraisal of metabolic syndrome and type 2 diabetes may improve our understanding of these diseases and set a basis for a comprehensive approach in their treatment.

Glucose transporters (GLUT and SGLT): expanded families of sugar transport proteins

The number of known glucose transporters has expanded considerably over the past 2 years. At least three, and up to six, Na+-dependent glucose transporters (SGLT1-SGLT6; gene name SLC5A) have been identified. Similarly, thirteen members of the family of facilitative sugar transporters (GLUT1-GLUT12 and HMIT; gene name SLC2A) are now recognised. These various transporters exhibit different substrate specificities, kinetic properties and tissue expression profiles. The number of distinct gene products, together with the presence of several different transporters in certain tissues and cells (for example, GLUT1, GLUT4, GLUT5, GLUT8, GLUT12 and HMIT in white adipose tissue), indicates that glucose delivery into cells is a process of considerable complexity.

Global and societal implications of the diabetes epidemic

Changes in human behaviour and lifestyle over the last century have resulted in a dramatic increase in the incidence of diabetes worldwide. The epidemic is chiefly of type 2 diabetes and also the associated conditions known as 'diabesity' and 'metabolic syndrome'. In conjunction with genetic susceptibility, particularly in certain ethnic groups, type 2 diabetes is brought on by environmental and behavioural factors such as a sedentary lifestyle, overly rich nutrition and obesity. The prevention of diabetes and control of its micro- and macrovascular complications will require an integrated, international approach if we are to see significant reduction in the huge premature morbidity and mortality it causes.