Clinical implications of the insulin resistance syndrome

NGAL and SMAD1 gene expression in the early detection of diabetic nephropathy by liquid biopsy

INTRODUCTION

Diabetic nephropathy (DN) is a disease that progresses with the slow and progressive decline of the glomerular filtration rate (GFR); the installation of this pathology is silent and one of the major causes of death in patients with diabetes.

AIMS

To identify new molecular biomarkers for early identification of the onset of DN in patients with type II diabetes mellitus (DM2). We studied the expression profile of the genes; suppressor of mothers against decapentaplegic type 1 (SMAD1), neutrophil gelatinase-associated lipocalin (NGAL) and type IV collagen (COLIV1A) in peripheral blood and urine sediment samples.

METHODS

Ninety volunteers, 51 with DM2 and 39 healthy, were recruited from the Faculdade de Medicina do ABC outpatient clinic. We conducted an interview and collected anthropometric data, as well as blood and urine samples for biochemical evaluation and real-time PCR amplification of the genes of interest.

RESULTS

Gene expression data: peripheral blood NGAL (DM2 0.09758±0.1914 vs CTL 0.02293±0.04578), SMAD1 (blood: DM2 0.01102±0.04059* vs CTL 0.0001317±0.0003609; urine: DM2 0.7195±2.344* vs CTL 0.09812±0.4755), there was no significant expression of COLIV1A. These genes demonstrated good sensitivity and specificity in the receiving operating characteristic curve evaluation.

CONCLUSION

Our data suggest the potential use of NGAL and SMAD1 gene expression in peripheral blood and urine samples as early biomarkers of DN.

Effects of a stimulant-free dietary supplement on body weight and fat loss in obese adults: a six-week exploratory study

BACKGROUND

Obesity is a well-established risk factor for cardiovascular disease, diabetes, hyperlipidemia, hypertension, osteoarthritis, and stroke. Stimulants, such as ephedrine and caffeine and their herbal counterparts, have proved effective in facilitating body weight loss, but their use is controversial due to their undesired effects. Other nutraceuticals have shown moderate success in reducing body weight, whereas several other compounds have demonstrated little or no effect. Therefore, a tolerable and effective nutraceutical that can increase energy expenditure and/or decrease caloric intake is desirable for body weight reduction.

OBJECTIVE

The primary purpose of this study was to assess the tolerability and effectiveness of a novel, stimulant-free, dietary supplement containing glucomannan, chitosan, fenugreek, Gymnema sylvestre, and vitamin C on body weight and fat loss and change in body composition in obese adults.

METHODS

In this single-center, prospective, randomized, double-blind, placebo-controlled study conducted at the University of Guelph (Guelph, Ontario, Canada), obese adults (aged 20-50 years; body mass index [BMI], ≥30 kg/m(2)) were randomized to the treatment or placebo group. The treatment group received 6 capsules of a dietary supplement containing a proprietary blend of glucomannan, chitosan, fenugreek, G sylvestre, and vitamin C daily for 6 weeks, and the placebo group received 6 capsules of rice flour daily for 6 weeks. Body weight; percentage of body fat; absolute fat mass; lean body mass; BMI; upper abdominal, waist, and hip circumference; and anthropometric measurements were recorded at baseline and at study end. Patients completed daily dietary intake records on days 1 to 3 and days 40 to 42. They also completed weekly activity logs throughout the study.

RESULTS

Twenty-four subjects (mean [SD] age, 37.0 [8.2] years [range, 21-48years]; mean [SD] BMI, 35.7 [6.2] kg/m(2) [range, 28.9-50.9 kg/m(2)]) were assigned to the treatment group (8 women, 4 men) or the placebo group (9 women,3 men). Two subjects (8.3%; 1 patient [8.3%] from each group) dropped out for personal reasons unrelated to the study. No significant changes in the consumption of total calories; the percentage of calories ingested as carbohydrates, fat, or protein; or activity levels were found in either group throughout the study. Compared with the placebo group, the treatment group lost significantly more body weight (-2.3 kg vs 0.0 kg; P<0.01), percentage of body fat (-1.1% vs 0.2%; P<0.05), and absolute fat mass (-2.0 kg vs 0.2 kg; P<0.001). The treatment group also experienced a significantly greater reduction in upper abdominal circumference (-4.5 cm vs -0.7 cm), waist circumference (-4.1 cm vs 0.1 cm), and hip circumference (-2.9 cm vs 0.6 cm) compared with the placebo group (P<0.05 for all). No significant changes in heart rate or blood pressure were found in either group. Both the treatment and the placebo were well tolerated.

CONCLUSION

Within the context of this study, the novel combination of glucomannan, chitosan, fenugreek, G sylvestre, and vitamin C results in significant body weight and fat loss in obese adults. Disclosure: Derek E. Woodgate, MSc, is president and owner of NxCare Inc., which produces the dietary supplement containing glucomannan, chitosan, fenugreek, Gymnema sylvestre, and vitamin C (trade name Calorie-Care™).

Managing Atherosclerosis in Patients with Type 2 Diabetes Mellitus and Metabolic Syndrome

Diabetes mellitus with its increasing prevalence is a major global health problem in United States. Macrovascular complications, especially atherosclerosis, are the major cause of morbidity and mortality in patients with type 2 diabetes mellitus. Metabolic syndrome is considered to be a metabolic precursor of type 2 diabetes mellitus and is an independent risk factor in the pathogenesis of atherosclerosis. It is a constellation of proatherogenic metabolic abnormalities, which include obesity, hypertension, characteristic dyslipidemia, hyperglycemia, insulin resistance, and compensatory hyperinsulinemia. Recent epidemiological data have demonstrated a strong causal association between insulin resistance and coronary vascular disease independent of hyperglycemia associated with type 2 diabetes mellitus. Given the high prevalence of metabolic syndrome in the general population and its role in the pathogenesis of atherosclerosis, every attempt should be made to recognize early the metabolic syndrome and to modify the associated proatherogenic metabolic abnormalities. Management of atherosclerosis in insulin-resistant states like metabolic syndrome and type 2 diabetes is a multifactorial process involving nonpharmacological interventions like exercise, diet control, and pharmacological therapy directed at hypertension, hyperglycemia, and dyslipidemia. Further research is warranted to demonstrate the effects of these interventions unequivocally in preventing the progression of metabolic syndrome to overt type 2 diabetes mellitus with its associated macrovascular complications.

Role of exercise training on cardiovascular disease in persons who have type 2 diabetes and hypertension

Exercise training is an essential component in the medical management of patients who have type 2 diabetes and hypertension. Regular exercise improves the cardiovascular health of individuals who have these conditions through multiple mechanisms (Fig. 1). These mechanisms include improvements in endothelial vasodilator function,left ventricular diastolic function, arterial stiffness.systematic inflammation, and reducing left ventricular mass. Exercise training also reduces total and abdominal fat, which mediate improvements in insulin sensitivity and blood pressure, and possibly, endothelial function. Persons who are in a prediabetic stage or those who have the metabolic syndrome may be able to prevent or delay the progression to overt diabetes by adopting a healthier lifestyle, of which increasing habitual levels of physical activity isa vital component. Most persons who have diabetes and hypertension or are at risk for these conditions should be able to initiate an exercise program safely after appropriate medical screen-ing and the establishment of an individualized exercise prescription. Despite the increasing amount of evidence that shows the benefits of exercise training, this modality of prevention and treatment continues to be underused. Although patients' lack of knowledge of the benefits of exercise or lack of motivation contributes to this underuse, a lack of clear and specific guidelines from health care professionals also is an important factor. Clinicians need to educate patients about the benefits of exercise for managing their type 2 diabetes and assist in formulating specific advice for increasing physical activity. Specific instructions should be given to patients, rather than general advice, such as "you should exercise more often." Many cardiac re-habilitation and clinical exercise programs can accommodate patients who have type 2 diabetes and hypertension. Such programs can establish individualized exercise prescriptions and provide an environment that is conducive for "lifestyle change" that underlies long-term compliance to exercise and risk factor modification.

What is the relationship between exercise and metabolic abnormalities? A review of the metabolic syndrome

Prevention of the metabolic syndrome and treatment of its main characteristics are now considered of utmost importance in order to combat the epidemic of type 2 diabetes mellitus and to reduce the increased risk of cardiovascular disease and all-cause mortality. Insulin resistance/hyperinsulinaemia are consistently linked with a clustering of multiple clinical and subclinical metabolic risk factors. It is now widely recognised that obesity (especially abdominal fat accumulation), hyperglycaemia, dyslipidaemia and hypertension are common metabolic traits that, concurrently, constitute the distinctive insulin resistance or metabolic syndrome. Cross-sectional and prospective data provide an emerging picture of associations of both physical activity habits and cardiorespiratory fitness with the metabolic syndrome. The metabolic syndrome, is a disorder that requires aggressive multi-factorial intervention. Recent treatment guidelines have emphasised the clinical utility of diagnosis and an important treatment role for 'therapeutic lifestyle change', incorporating moderate physical activity. Several previous narrative reviews have considered exercise training as an effective treatment for insulin resistance and other components of the syndrome. However, the evidence cited has been less consistent for exercise training effects on several metabolic syndrome variables, unless combined with appropriate dietary modifications to achieve weight loss. Recently published randomised controlled trial data concerning the effects of exercise training on separate metabolic syndrome traits are evaluated within this review. Novel systematic review and meta-analysis evidence is presented indicating that supervised, long-term, moderate to moderately vigorous intensity exercise training, in the absence of therapeutic weight loss, improves the dyslipidaemic profile by raising high density lipoprotein-cholesterol and lowering triglycerides in overweight and obese adults with characteristics of the metabolic syndrome. Lifestyle interventions, including exercise and dietary-induced weight loss may improve insulin resistance and glucose tolerance in obesity states and are highly effective in preventing or delaying the onset of type 2 diabetes in individuals with impaired glucose regulation. Randomised controlled trial evidence also indicates that exercise training decreases blood pressure in overweight/obese individuals with high normal blood pressure and hypertension. These evidence-based findings continue to support recommendations that supervised or partially supervised exercise training is an important initial adjunctive step in the treatment of individuals with the metabolic syndrome. Exercise training should be considered an essential part of 'therapeutic lifestyle change' and may concurrently improve insulin resistance and the entire cluster of metabolic risk factors.

The roles of insulin resistance, hyperinsulinemia, and thiazolidinediones in cardiovascular disease

Although it is difficult to distinguish between the relative effects of insulin resistance and hyperinsulinemia, insulin resistance is clearly associated with significantly increased cardiovascular and cerebrovascular risk. This effect is consistent across the spectrum of worsening glycemic control, from the onset of impaired glucose tolerance to the development of clinical diabetes. It is more difficult to discriminate between the roles of elevated circulating insulin and proinsulin levels; the association between insulin levels and cardiovascular risk is weak. The thiazolidinediones (TZDs) significantly improve insulin sensitivity and exert numerous effects on the vascular bed, including improved endothelial function, decreased vascular inflammation, decreased plasma free fatty acid levels, improved dyslipidemic profiles, and inhibition of vascular smooth muscle proliferation. These findings provide increasing evidence to suggest that the TZDs may have a beneficial effect on atherosclerosis and may reduce the incidence and severity of adverse cardiovascular outcomes. These effects remain to be substantiated by the results of large outcomes studies to evaluate the impact of glycemic control and reversal of insulin resistance on cardiovascular events.

[Prevention of stroke]

In the past years, research on cardiovascular prevention was among the fields with the most pronounced medical progress. Actually, a substantial proportion of strokes could be avoided given a strict consideration of the currently available prevention guidelines. The current review summarizes the most compelling studies and meta-analyses on this issue and depicts the main consequences and resulting recommendations. Apart from classic risk factors there is a special focus on new risk concepts including toxic effects of homocystine, the 'iron hypothesis' and the intriguing issues of inflammation and chronic infection. In addition, there will be a dispute on challenges regarding carotid surgery and optimal drug therapy as well as on dietary guidelines.

The role played by neural crest cells in the development of syndrome X: a hypothesis

This study evaluated the components and the related hormone releasing organs, the mechanism of action of these hormones, and the origins of the cells and organs in a disorder known as metabolic syndrome X, the prevalence of which is rapidly increasing particularly among the adult population of industrial societies. Metabolic syndrome X, involving carbohydrate and lipid metabolism disorders and cardiovascular disorders caused by the release of primary hormones, alpha and beta cells of the islets of Langerhans of pancreas, adrenal gland medulla's chromaffin cells, sympathetic nervous system neurons and ganglia, adenohypophysis, neurohypophysis and hypothalamus, were evaluated for being neuroectodermal and mainly having neural crest origin. Generally the cells, tissues and organs involved are neuroectodermal and especially have neural crest origins; and to conclude, in prevention, diagnosis and treatment of this disorder the priority is the analysis and understanding of the migration, differentiation and adaptation at the target of neural crest cells.

Evidence for joint action of genes on diabetes status and CVD risk factors in American Indians: the strong heart family study

OBJECTIVES

Previous research among American Indians of the strong heart family study (SHFS) has demonstrated significant heritabilities for CVD risk factors and implicated diabetes as an important predictor of several of the phenotypes. Moreover, we recently demonstrated that genetic effects on CVD risk factors differed in diabetic and nondiabetic individuals. In this paper, we investigated whether a significant genetic influence on diabetes status could be identified, and whether there is evidence for joint action of genes on diabetes status and related CVD risk factors.

METHODS AND RESULTS

Approximately 950 men and women, age 18 or older, in 32 extended families, were examined between 1997 and 1999. We estimated the effects of genes and environmental covariates on diabetes status using a threshold model and a maximum likelihood variance component approach. Diabetes status exhibited a residual heritability of 22% (h2=0.22). We also estimated the genetic and environmental correlations between diabetes susceptibility and eight risk factors for CVD. All eight CVD risk factors displayed significant genetic correlations with diabetes status (BMI (rhoG=0.55), fibrinogen (rhoG=0.40), HDL-C (rhoG=-0.37), ln triglycerides (rhoG=0.65), FAT (rhoG=0.38 ), PAI-1 (rhoG=0.67), SBP (rhoG=0.57), and WHR (rhoG=0.58)). Three of eight traits (HDL-C (rhoE=-0.32), ln triglycerides (rhoE=0.33), and fibrinogen (rhoE=0.20)) displayed significant environmental correlations with diabetes status.

CONCLUSIONS

These findings suggest that in the context of a high prevalence of diabetes, still unidentified diabetes genes may play an important role in influencing variation in CVD risk factors.

Postprandial hyperglycemia and insulin sensitivity differ among lean young adults of different ethnicities

Both postprandial hyperglycemia and insulin resistance (IR) have implications for the development of cardiovascular disease. The present study was designed to examine differences in postprandial glycemia and insulin sensitivity among young adults of different ethnic origins. Lean, healthy subjects (n = 60) from five ethnic groups [20 European Caucasians, 10 Chinese, 10 South East (SE) Asians, 10 Asian Indians and 10 Arabic Caucasians] were matched for age, body mass index, waist circumference, birth weight and current diet. A 75-g white bread carbohydrate challenge was fed to assess postprandial glycemia and insulinemia. Insulin sensitivity was assessed in three groups by the euglycemic-hyperinsulinemic clamp and in all subjects by homeostasis model assessment (HOMA) modeling. Postprandial hyperglycemia (incremental area under the curve) and insulin sensitivity (M-value) both showed a twofold variation among the groups (P < 0.001) and were significantly related to each other (R(2) = 56%, P < 0.001). Young SE Asians had the highest postprandial glycemia and lowest insulin sensitivity, whereas European and Arabic Caucasian subjects were the most insulin sensitive and carbohydrate tolerant. These findings suggest that IR is evident even in lean, young adults of some ethnic groups and is associated with significant increases in postprandial glycemia and insulinemia in response to a realistic carbohydrate load.