The role of beta-cell dysfunction in the cardiometabolic syndrome

Association of Biomarkers for Dyslipidemia, Inflammation, and Oxidative Stress with Endothelial Dysfunction in Obese Youths: A Case-Control Study

Objective

The United Arab Emirates (UAE), with its characteristic local population, geography, and history, presents several risk factors for cardiovascular diseases (CVDs) in obese individuals. Obesity and its associated complications, including diabetes, atherogenic dyslipidemia, and CVDs leading to significant health risks. In the present study, "Youths" defined as young people between 18 and 22 years. We assessed dyslipidemia, inflammation, and oxidative stress biomarker levels and their association with endothelial dysfunction (ED) in both overweight/obese and normal weight youths of UAE.

Methods

There were 160 youths with overweight/obese (BMI ≥ 25 kg/m2) patients and healthy age- and sex-matched normal weight (BMI ≤ 24.9 kg/m2) as controls participated in this study. The anthropometric data and blood samples were collected to assess the biomarkers for dyslipidemia, inflammation, oxidative stress, ED from all the youths.

Results

The overall mean age and male-to-female ratio were 20±1.5years and 1.0:1.2, respectively. There was statistically significant difference in HDL-C (p<0.001), triglycerides (TG) (p<0.001), ApoA (p=0.002), ApoB/ApoA ratio (p=0.009) between the overweight/obese and normal weight youths. Among, inflammatory markers: hs-CRP, IL-6, TNF-α also showed significant p<0.001 and oxidative stress markers: DNA/RNA Damage, catalase and nitric oxide (NO) showed significant p<0.001 between groups. Spearman correlation of ED markers with lipid profile markers showed Vitamin C levels positively correlated with HDL-C (p<0.001) and negatively correlated with glucose (p<0.001). ICAM-1showed significant negative correlation with HDL-C (p<0.01) and ApoA (p<0.001) but positive correlation with TG (p<0.01) and HbA1c (p<0.001) among groups. Spearman correlation of ED markers with inflammatory/oxidative stress biomarkers showed Vitamin C levels negatively correlated with ferritin (p < 0.001), NO (p < 0.001), GGT (p < 0.001), and ALT (p < 0.001) levels. The ICAM-1showed significant positive correlation with hs-CRP (p < 0.01), IL-6 (p < 0.001), TNF-α (p < 0.01), GGT (p < 0.05), and ALT (p < 0.05) in both groups.

Conclusion

This study revealed a strong link between the biomarkers of dyslipidemia, inflammation, and oxidative stress with ED in overweight/obese patients. This study might be used to predict future cardiovascular events in this population.

Endoplasmic reticulum stress: bridging inflammation and obesity-associated adipose tissue

Obesity presents a significant global health challenge, increasing the susceptibility to chronic conditions such as diabetes, cardiovascular disease, and hypertension. Within the context of obesity, lipid metabolism, adipose tissue formation, and inflammation are intricately linked to endoplasmic reticulum stress (ERS). ERS modulates metabolism, insulin signaling, inflammation, as well as cell proliferation and death through the unfolded protein response (UPR) pathway. Serving as a crucial nexus, ERS bridges the functionality of adipose tissue and the inflammatory response. In this review, we comprehensively elucidate the mechanisms by which ERS impacts adipose tissue function and inflammation in obesity, aiming to offer insights into targeting ERS for ameliorating metabolic dysregulation in obesity-associated chronic diseases such as hyperlipidemia, hypertension, fatty liver, and type 2 diabetes.

Oxidative stress: The nexus of obesity and cognitive dysfunction in diabetes

Obesity has been associated with oxidative stress. Obese patients are at increased risk for diabetic cognitive dysfunction, indicating a pathological link between obesity, oxidative stress, and diabetic cognitive dysfunction. Obesity can induce the biological process of oxidative stress by disrupting the adipose microenvironment (adipocytes, macrophages), mediating low-grade chronic inflammation, and mitochondrial dysfunction (mitochondrial division, fusion). Furthermore, oxidative stress can be implicated in insulin resistance, inflammation in neural tissues, and lipid metabolism disorders, affecting cognitive dysfunction in diabetics.

Exploring the effect of Crinum latifolia in obesity: possible role of oxidative, angiogenic, and inflammatory pathways

Obesity is a multifaceted disease encompassing deposition of an unnecessary amount of fat which upsurges the possibility of other complications, viz., hypertension and certain type of cancers. Although obesity results from combination of genetic factors, improper diet and inadequate physical exercise also play a major role in its onset. The present study aims at exploring the anti-obesity activity of Crinum latifolia leaf extract in obese rats. The leaves were extracted using hydroalcoholic extraction which was later diluted with water and given to obese rats. The dosing was started from the 4^th week (by oral administration of extract of Crinum latifolia (100 mg/kg and 200 mg/kg) and combination of Crinum latifolia leaf extract 200 mg/kg and orlistat 30 mg/kg) till the 10^th week. Various angiogenic, antioxidant, biochemical, and inflammatory biomarkers were assessed at the end of the study. The obese symptoms were progressively reduced in treatment groups when compared to disease control groups. The angiogenic parameters and inflammatory parameters were consequently reduced in treatment groups. The oxidative parameters superoxide dismutase (SOD) and catalase were gradually increased, while levels of TBARS were reduced in treatment groups showing antioxidant nature of leaf hydroalcoholic extract. The Crinum latifolia leaf extract possesses anti-obesity properties and therefore can be used as a therapeutic option in the management of obesity.

Sex differences in oxidative stress level and antioxidative enzymes expression and activity in obese pre-diabetic elderly rats treated with metformin or liraglutide

Aim

To determine the effects of metformin or liraglutide on oxidative stress level and antioxidative enzymes gene transcription and activity in the blood and vessels of pre-diabetic obese elderly Sprague-Dawley (SD) rats of both sexes.

Methods

Male and female SD rats were assigned to the following groups: a) control group (fed with standard rodent chow); b) high-fat and high-carbohydrate diet (HSHFD) group fed with HSHFD from 20-65 weeks of age; c) HSHFD+metformin treatment (50 mg/kg/d s.c.); and d) HSHFD+liraglutide treatment (0.3 mg/kg/d s.c). Oxidative stress parameters (ferric reducing ability of plasma and thiobarbituric acid reactive substances) and superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activity and gene transcription were determined from serum, aortas, and surface brain blood vessels (BBV).

Results

HSHFD increased body weight in both sexes compared with the control group, while liraglutide prevented this increase. Blood glucose level did not change. The liraglutide group had a significantly increased antioxidative capacity compared with the HSHFD group in both sexes. The changes in antioxidative enzymes’ activities in plasma were more pronounced in male groups. The changes in gene expression of antioxidative enzymes were more prominent in microvessels and may be attributed to weight gain prevention.

Conclusions

Obesity and antidiabetic drugs caused sex-related differences in the level of antioxidative parameters. Liraglutide exhibited stronger antioxidative effects than metformin. These results indicate that weight gain due to HSHFD is crucial for developing oxidative stress and for inhibiting antioxidative protective mechanisms.

An Immediate and Long-Term Complication of COVID-19 May Be Type 2 Diabetes Mellitus: The Central Role of β-Cell Dysfunction, Apoptosis and Exploration of Possible Mechanisms

The novel coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was declared a pandemic by the WHO on 19 March 2020. This pandemic is associated with markedly elevated blood glucose levels and a remarkable degree of insulin resistance, which suggests pancreatic islet β-cell dysfunction or apoptosis and insulin's inability to dispose of glucose into cellular tissues. Diabetes is known to be one of the top pre-existing co-morbidities associated with the severity of COVID-19 along with hypertension, cardiocerebrovascular disease, advanced age, male gender, and recently obesity. This review focuses on how COVID-19 may be responsible for the accelerated development of type 2 diabetes mellitus (T2DM) as one of its acute and suspected long-term complications. These observations implicate an active role of metabolic syndrome, systemic and tissue islet renin-angiotensin-aldosterone system, redox stress, inflammation, islet fibrosis, amyloid deposition along with β-cell dysfunction and apoptosis in those who develop T2DM. Utilizing light and electron microscopy in preclinical rodent models and human islets may help to better understand how COVID-19 accelerates islet and β-cell injury and remodeling to result in the long-term complications of T2DM.

Bioassay-guided isolation of active anti-adipogenic compound from royal jelly and the study of possible mechanisms

Background

Royal jelly (RJ) has been used traditionally for dietary, cosmetic and health purposes for a long time in different parts of the world. Scientific studies have also shown its numerous health-promoting properties including hypoglycemic and anti-hypercholesterolemic action. In this study, we investigated the anti-adipogenic activity of RJ in 3 T3-L1 cells and isolated the major responsible root component for the activity.

Methods

An active anti-adipogenic compound was isolated through bioassay-guided isolation process by successive treatment of RJ and its active fractions on 3 T3-L1 cell line. (E)-10-Hydroxy-2-decenoic Acid (10-HDA) was identified using NMR spectroscopy and ultra-performance liquid chromatography (UPLC). As 10-HDA showed significant anti-adipogenic activity with Oil Red O staining and TG content assay on 3 T3-L1 adipocytes, further study was carried out in molecular level for the expression of adipogenic transcription factors such as PPARγ, FABP4, C/EBPα, SREBP-1c, and Leptin. The effect of 10-HDA on preliminary molecules such as pAkt, pERK, C/EBPβ, and pCREB were studied in the early stage of adipogenesis. The effect of 10-HDA on reactive oxygen species (ROS) production in fully differentiating adipocytes was measured by nitro blue tetrazolium (NBT) assay.

Result

Results showed that triacylglycerol accumulation and ROS production was markedly suppressed by 10-HDA. Preliminary molecules such as pAkt, pERK, pCERB, and C/EBPβ were found to be down-regulated by 10-HDA, which led to down-regulation of key adipogenic transcription factors such as PPARγ, FABP4, CEBPα, SREBP-1c, and Leptin on 3 T3-L1 adipocytes.

Conclusion

Our results suggest that anti-adipogenesis of 10-HDA on 3 T3-L1 adipocyte takes place via two mechanisms: inhibition of cAMP/PKA pathway and inhibition of p-Akt and MAPK dependent insulin signaling pathway. So it is considered that 10-HDA, a major component of RJ, can be a potential therapeutic medicine for obesity.

Electronic supplementary material

The online version of this article (10.1186/s12906-018-2423-2) contains supplementary material, which is available to authorized users.

Insulin resistance and β-cell dysfunction and the relationship with cardio-metabolic disorders among women with polycystic ovary syndrome

OBJECTIVE

To investigate both independent and combined effects of insulin resistance and β-cell dysfunction on cardio-metabolic abnormalities in polycystic ovary syndrome (PCOS).

DESIGN

A national epidemiologic survey was performed in reproductive aged females in China from October 2007 to September 2011.

METHODS

A total of 824 PCOS and 2715 non-PCOS were included. The Rotterdam Criteria were applied for PCOS diagnosis. We used the homeostasis model assessment of insulin resistance (HOMA-IR) and HOMA of β-cell function (HOMA-β) to evaluate insulin resistance and β-cell dysfunction, respectively.

RESULTS

Compared with non-PCOS, PCOS showed a higher index of HOMA-IR and HOMA-β, and a higher prevalence of obesity, central obesity, and dyslipidaemia. High HOMA-IR was independently related to a high prevalence of obesity, central obesity, dyslipidaemia, and high blood glucose in PCOS. In contrast, a low index of HOMA-β index was independently correlated with a low prevalence of obesity, and central obesity, but negatively correlated with an elevated prevalence of high blood glucose in PCOS. In addition, proportion of insulin resistance was higher than that of β-cell dysfunction in PCOS with cardio-metabolic disorders. β-cell dysfunction was negatively correlated with the prevalence of central obesity and obesity.

CONCLUSIONS

Insulin resistance and β-cell dysfunction independently affected cardio-metabolic abnormalities in PCOS, while insulin resistance was correlated with a higher prevalence of cardio-metabolic abnormalities than that of β-cell dysfunction. Moreover, β-cell dysfunction and insulin resistance showed divergent correlations with obesity in PCOS.

Metabolic Effects of Metformin in the Failing Heart

Accumulating evidence shows that metformin is an insulin-sensitizing antidiabetic drug widely used in the treatment of type 2 diabetes mellitus (T2DM), which can exert favorable effects on cardiovascular risk and may be safely used in patients with heart failure (HF), and even able to reduce the incidence of HF and to reduce HF mortality. In failing hearts, metformin improves myocardial energy metabolic status through the activation of AMP (adenosine monophosphate)-activated protein kinase (AMPK) and the regulation of lipid and glucose metabolism. By increasing nitric oxide (NO) bioavailability, limiting interstitial fibrosis, reducing the deposition of advanced glycation end-products (AGEs), and inhibiting myocardial cell apoptosis metformin reduces cardiac remodeling and hypertrophy, and thereby preserves left ventricular systolic and diastolic functions. While a lot of preclinical and clinical studies showed the cardiovascular safety of metformin therapy in diabetic patients and HF, to confirm observed benefits, the specific large-scale trials configured for HF development in diabetic patients as a primary endpoints are necessary.

Antidyslipidemic, Anti-Inflammatory, and Antioxidant Activities of Aqueous Leaf Extract of Dioscoreophyllum cumminsii (Stapf) Diels in High-Fat Diet-Fed Rats

Dioscoreophyllum cumminsii (Stapf) Diels leaves are widely used in the treatment of diabetes, obesity, and cardiovascular related complications in Nigeria. This study investigates the anti-inflammatory and antiobesity effect of aqueous extract of Dioscoreophyllum cumminsii leaves in high-fat diet- (HFD-) induced obese rats. HFD-fed rats were given 100, 200, and 400 mgkg-1 body weight of aqueous extract of Dioscoreophyllum cumminsii leaves for 4 weeks starting from 9th week of HFD treatment. D. cumminsii leaves aqueous extract reversed HFD-mediated decrease in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glucose 6-phosphate dehydrogenase. Moreover, HFD-mediated elevation in the levels of conjugated dienes, lipid hydroperoxides, malondialdehyde, protein carbonyl, and DNA fragmentation in rats liver was lowered. HFD-mediated alterations in serum total cholesterol, triacylglycerol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and very low-density lipoprotein cholesterol were significantly reversed by the extract. The treatment of HFD-fed rats reduced the levels of insulin, leptin, protein carbonyl, fragmented DNA, and tumour necrosis factor-α and interleukin- (IL-) 6 and IL- 8 and increased the adiponectin level. This study showed that aqueous extract of Dioscoreophyllum cumminsii leaves has potential antiobesity and anti-inflammatory effects through modulation of obesity-induced inflammation, oxidative stress, and obesity-related disorder in HFD-induced obese rats.

Obesity, cardiovascular disease, and role of vitamin C on inflammation: a review of facts and underlying mechanisms

Obesity means the accumulation of excessive fat that may interfere with the maintenance of optimal state of health. Obesity causes cardiac and vascular disease through well-known mediators such as hypertension, type-2 diabetes mellitus, and dyslipidemia, but there are evidences for other mediators such as chronic inflammation, oxidative stress, and thrombosis. The decreased levels of antioxidants factors and nitric oxide predispose to further cardiovascular adverse events. To reduce the risks, antioxidants can help by neutralizing the free radicals and protecting from damage by donating electrons. Having the capacity, vitamin C protects from oxidative stress, prevention of non-enzymatic glycosylation of proteins, and enhances arterial dilation through its effect on nitric oxide release. It also decreases lipid peroxidation, and alleviates inflammation. The anti-inflammatory property of vitamin C could be attributed to ability to modulate the NF-_kB DNA binding activity and down-regulation in the hepatic mRNA expression for the interleukins and tumor factors.

Enzymatic antioxidant system in vascular inflammation and coronary artery disease

In biological systems there is a balance between the production and neutralization of reactive oxygen species (ROS). This balance is maintained by the presence of natural antioxidants and antioxidant enzymes such as superoxide dismutase (SOD), catalase and glutathione peroxidase. The enhancement of lipid peroxidation or the decrease of antioxidant protection present in metabolic diseases or bad lifestyle can induce endothelial dysfunction and atherosclerosis. Clinical studies have shown that oxidative stress can increase ROS reducing the formation of antioxidant defences, especially in subjects with coronary artery disease (CAD). Some observation indicated that in the early stages of the disease there is a homeostatic up-regulation of the antioxidant enzyme system in response to increased free radicals to prevent vascular damage. As soon as free radicals get to chronically elevated levels, this compensation ceases. Therefore, SOD and the other enzymes may represent a good therapeutic target against ROS, but they are not useful markers for the diagnosis of CAD. In conclusion antioxidant enzymes are reduced in presence of metabolic disease and CAD. However the existence of genes that promote their enzymatic activity could contribute to create new drugs for the treatment of damage caused by metabolic diseases or lifestyle that increases the plasma ROS levels.

Influence of adiposity on insulin resistance and glycemia markers among U.K. Children of South Asian, black African-Caribbean, and white European origin: child heart and health study in England

OBJECTIVE

Ethnic differences in type 2 diabetes risk between South Asians and white Europeans originate before adult life and are not fully explained by higher adiposity levels in South Asians. Although metabolic sensitivity to adiposity may differ between ethnic groups, this has been little studied in childhood. We have therefore examined the associations among adiposity, insulin resistance, and glycemia markers in children of different ethnic origins.

RESEARCH DESIGN AND METHODS

Cross-sectional study of 4,633 9- to 10-year-old children (response rate 68%) predominantly of South Asian, black African-Caribbean, and white European origin (n = 1,266, 1,176, and 1,109, respectively) who had homeostasis model assessments of insulin resistance (HOMA-IR), glycemia markers (HbA1c and fasting glucose), and adiposity (BMI, waist circumference, skinfold thicknesses, and bioimpedance [fat mass]).

RESULTS

All adiposity measures were positively associated with HOMA-IR in all ethnic groups, but associations were stronger among South Asians compared to black African-Caribbeans and white Europeans. For a 1-SD increase in fat mass percentage, percentage differences in HOMA-IR were 37.5% (95% CI 33.3-41.7), 29.7% (25.8-33.8), and 27.0% (22.9-31.2), respectively (P interaction < 0.001). All adiposity markers were positively associated with HbA1c in South Asians and black African-Caribbeans but not in white Europeans; for a 1-SD increase in fat mass percentage, percentage differences in HbA1c were 0.04% (95% CI 0.03-0.06), 0.04% (0.02-0.05), and 0.02% (-0.00 to 0.04), respectively (P interaction < 0.001). Patterns for fasting glucose were less consistent.

CONCLUSIONS

South Asian children are more metabolically sensitive to adiposity. Early prevention or treatment of childhood obesity may be critical for type 2 diabetes prevention, especially in South Asians.

Agrimonia eupatoria tea consumption in relation to markers of inflammation, oxidative status and lipid metabolism in healthy subjects

Phytotherapy reports strong anti-oxidative and anti-inflammatory potential of agrimony (Agrimonia eupatoria L.). However the effects of agrimony tea consumption are not scientifically proven in humans. We investigated the effects of one month's consumption of agrimony tea in healthy volunteers. Significant elevation of plasma total antioxidant capacity was observed and interleukin 6 levels were significantly lowered at the end of the intervention. An improved lipid profile as estimated by increased high density lipoprotein (HDL) cholesterol was established upon agrimony tea supplementation and HDL cholesterol correlated with adiponectin levels. The results presented in this first human intervention study with agrimony tea indicate that the plant has potential in improving markers of lipid metabolism, oxidative status and inflammation in healthy adults.

Advanced research on risk factors of type 2 diabetes

The prevalence of type 2 diabetes is increasing globally and poses a heavy burden on public health and socioeconomic development of all nations. Type 2 diabetes is a multifactorial disease and due to a combination of environmental and genetic risk factors. Many environmental risk factors contribute to the pathogenesis of type 2 diabetes, including lifestyles such as sedentary behaviour, diet, smoking and alcohol consumption, internal environmental factors such as inflammatory factors, adipocytokines and hepatocyte factors, external environmental factors such as environmental endocrine disruptors. This review summarizes current research efforts concentrated on the contributors for accelerated type 2 diabetes epidemic. It also provides a novel prospect for future researches.

The role of T-bet in obesity: lack of T-bet causes obesity in male mice

The association of T helper (Th) 1 cells with obesity is well documented in both animals and humans. The T-box transcription factor (T-bet) is known as the transcription factor that is responsible for the development of Th1 cells. However, the role of T-bet in obesity has never been elucidated. The present study aimed to investigate the regulatory function of T-bet on obesity in mice. Th1 cytokine levels were decreased, whereas Th2 cytokine level and GATA-3 messenger RNA (mRNA) expression were increased in T-bet knockout (KO) mice. T-bet KO male mice induced obesity as a result of increased body weight and food efficiency despite the fact that they feed a control diet. T-bet KO mice have an increase in weight of white adipose tissue and levels of triacylglyceride and low-density lipoprotein cholesterol. Interestingly, the expression levels of energy expenditure-related genes were decreased in T-bet KO mice. Both T-bet KO male and female mice had impaired glucose tolerance. In white adipose tissue, leptin, the increase in peroxisome proliferator receptor-γ and CAAT/enhancer-binding protein α mRNA expressions in T-bet KO mice was more than that in wild-type mice. Furthermore, we found that the level of interleukin (IL)-6 mRNA expression in white adipose tissue was elevated in T-bet KO mice but not IL-1β and tumor necrosis factor-α. IL-6 mRNA expression was increased in adipocyte fraction and stromal vascular fraction in white adipose tissue of T-bet KO mice. Taken together, our results reveal that T-bet may affect obesity through the regulation of IL-6 expression in adipocytes of white adipose tissue.

Angiotensin II-induced JNK activation is mediated by NAD(P)H oxidase in isolated rat pancreatic islets

Angiotensin II (AII), the active component of the renin angiotensin system (RAS), plays a vital role in the regulation of physiological processes of the cardiovascular system, but also has autocrine and paracrine actions in various tissues and organs. Many studies have shown the existence of RAS in the pancreas of humans and rodents. The aim of this study was to evaluate potential signaling pathways mediated by AII in isolated pancreatic islets of rats. Phosphorylation of MAPKs (ERK1/2, JNK and p38MAPK), and the interaction between proteins JAK/STAT were evaluated. AII increased JAK2/STAT1 (42%) and JAK2/STAT3 (100%) interaction without altering the total content of JAK2. Analyzing the activation of MAPKs (ERK1/2, JNK and p38MAPK) in isolated pancreatic islets from rats we observed that AII rapidly (3 min) promoted a significant increase in the phosphorylation degree of these proteins after incubation with the hormone. Curiously JNK protein phosphorylation was inhibited by DPI, suggesting the involvement of NAD(P)H oxidase in the activation of protein.

Cellular and molecular mechanisms of vascular injury in diabetes--part I: pathways of vascular disease in diabetes

Diabetes-induced micro- and macrovascular complications are the major causes of morbidity and mortality in diabetic patients. While hyperglycemia is a key factor for the pathogenesis of diabetic microvascular complications, it is only one of the multiple factors capable of increasing the risk of macrovascular complications. Hyperglycemia induces vascular damage probably through a single common pathway - increased intracellular oxidative stress - linking four major mechanisms, namely the polyol pathway, advanced glycation end-products (AGEs) formation, the protein kinase C (PKC)-diacylglycerol (DAG) and the hexosamine pathways. In addition, in conditions of insulin resistance, i.e., preceding the onset of type 2 diabetes, the phosphatidylinositol (PI) 3-kinase (PI3K)/Akt pathway is selectively inhibited, while the mitogen activated protein (MAP)-kinase pathway remains largely unaffected, thus allowing compensatory hyperinsulinemia to elicit pro-atherogenic events in vascular smooth muscle and endothelial cells, including increased cell proliferation, and the expression of plasminogen activator inhibitor-1, as well as of proinflammatory cytokines and endothelial adhesion molecules.

Nutrient intakes and dysglycaemia in populations of West African origin

Examining the relationship between glucose intolerance and dietary intake in genetically similar populations with different dietary patterns and rates of type 2 diabetes may provide important insights into the role of diet in the pathogenesis of this disease. The objective of the present study was to assess the relationship between dietary variables and dysglycaemia/type 2 diabetes among three populations of African origin. The study design consists of a cross-sectional study of men and women of African descent aged 24-74 years from Cameroon (n 1790), Jamaica (n 857) and Manchester, UK (n 258) who were not known to have diabetes. Each participant had anthropometric measurements and underwent a 2 h 75 g oral glucose tolerance test. Habitual dietary intake was estimated with quantitative FFQ, developed specifically for each country. The age-adjusted prevalence of undiagnosed type 2 diabetes in Cameroon was low (1·1 %), but it was higher in Jamaica (11·6 %) and the UK (12·6 %). Adjusted generalised linear and latent mixed models used to obtain OR indicated that each 1·0 % increment in energy from protein, total fat and saturated fats significantly increased the odds of type 2 diabetes by 9 (95 % CI 1·02, 1·16) %, 5 (95 % CI, 1·01, 1·08) % and 16 (95 % CI 1·08, 1·25) %, respectively. A 1 % increase in energy from carbohydrates and a 0·1 unit increment in the PUFA:SFA ratio were associated with significantly reduced odds of type 2 diabetes. The results show independent effects of dietary factors on hyperglycaemia in African origin populations. Whether modifying intake of specific macronutrients helps diabetes prevention needs testing in randomised trials.

Inflammation, oxidative stress, and obesity

Obesity is a chronic disease of multifactorial origin and can be defined as an increase in the accumulation of body fat. Adipose tissue is not only a triglyceride storage organ, but studies have shown the role of white adipose tissue as a producer of certain bioactive substances called adipokines. Among adipokines, we find some inflammatory functions, such as Interleukin-6 (IL-6); other adipokines entail the functions of regulating food intake, therefore exerting a direct effect on weight control. This is the case of leptin, which acts on the limbic system by stimulating dopamine uptake, creating a feeling of fullness. However, these adipokines induce the production of reactive oxygen species (ROS), generating a process known as oxidative stress (OS). Because adipose tissue is the organ that secretes adipokines and these in turn generate ROS, adipose tissue is considered an independent factor for the generation of systemic OS. There are several mechanisms by which obesity produces OS. The first of these is the mitochondrial and peroxisomal oxidation of fatty acids, which can produce ROS in oxidation reactions, while another mechanism is over-consumption of oxygen, which generates free radicals in the mitochondrial respiratory chain that is found coupled with oxidative phosphorylation in mitochondria. Lipid-rich diets are also capable of generating ROS because they can alter oxygen metabolism. Upon the increase of adipose tissue, the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), was found to be significantly diminished. Finally, high ROS production and the decrease in antioxidant capacity leads to various abnormalities, among which we find endothelial dysfunction, which is characterized by a reduction in the bioavailability of vasodilators, particularly nitric oxide (NO), and an increase in endothelium-derived contractile factors, favoring atherosclerotic disease.

Isletopathy in Type 2 diabetes mellitus: implications of islet RAS, islet fibrosis, islet amyloid, remodeling, and oxidative stress

This review focuses primarily on islet structural and functional changes related to an activated islet renin- angiotensin system (RAS), islet oxidative-redox imbalance, the concurrence of islet fibrosis (pericapillary, intra- and peri-islet), and islet amyloid deposition (pericapillary, intra- and peri-islet). The islet-acinar-portal vascular pathway and the emerging important anatomical and functional region, the islet-exocrine interface, are also discussed. Because there is an associated histopathological islet disease in type 2 diabetes mellitus (T2DM), the term isletopathy is discussed in detail. The isletopathy in T2DM is equally important as the other complications of diabetes. Special stains and special lighting (bright field and crossed polarized light) are utilized, along with light and transmission electron microscopy, in order to better understand islet structural remodeling in T2DM. The importance of an isletopathy in T2DM is supported by numerous remodeling changes within the islet and the islet-exocrine interface. While some of the structural findings are only preliminary observations, additional investigation in this area should lead to the development of new pathophysiological concepts and new therapies regarding the prevention and treatment of T2DM.