[Pathogenesis of type 2 diabetes mellitus]

Contribution of environmental determinants to the risk of developing type 2 diabetes mellitus in a life-course perspective: a systematic review protocol

BACKGROUND

Prevention policies against type 2 diabetes mellitus (T2DM) focus solely on individual healthy lifestyle behaviours, while an increasing body of research recognises the involvement of environmental determinants (ED) (cultural norms of land management and planning, local foodscape, built environment, pollution, and neighbourhood deprivation). Precise knowledge of this relationship is essential to proposing a prevention strategy integrating public health and spatial planning. Unfortunately, issues related to the consistency and synthesis of methods, and results in this field of research limit the development of preventive strategies. This systematic review aims to improve knowledge about the relationship between the risk of developing T2DM in adulthood and long-term exposure to its ED during childhood or teenage years.

METHODS

This protocol is presented according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) tools. PubMed, Embase, CINAHL, Web of Science, EBSCO, and grey literature from the Laval University Libraries databases will be used for data collection on main concepts such as 'type 2 diabetes mellitus', 'zoning' or 'regional, urban, or rural areas land uses', 'local food landscape', 'built environment', 'pollution', and 'deprivation'. The Covidence application will store the collected data for selection and extraction based on the Population Exposure Comparator Outcome and Study design approach (PECOS). Studies published until December 31, 2023, in English or French, used quantitative data about individuals aged 18 and over that report on T2DM, ED (cultural norms of land management and planning, local foodscape, built environment, and neighbourhood deprivation), and their association (involving only risk estimators) will be included. Then, study quality and risk of bias will be conducted according to the combined criteria and ratings from the ROBINS-E (Risk of Bias in Non-randomised Studies-of Exposures) tools and the 'Effective Public Health Practice Project' (EPHPP). Finally, the analytical synthesis will be produced using the 'Synthesis Without Meta-analysis' (SWiM) guidelines.

DISCUSSION

This systematic review will summarise available evidence on ED associated with T2DM. The results will contribute to improving current knowledge and developing more efficient cross-sectoral interventions in land management and public health in this field of research.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023392073.

Metabolic effects of Tofogliflozin are efficiently enhanced with appropriate dietary carbohydrate ratio and are distinct from carbohydrate restriction

Sodium‐glucose cotransporter 2 inhibitors (SGLT2i) exert their antidiabetic effects by promoting urinary glucose excretion. Nutrition therapy is obviously important, but little is known about the interactions between SGLT2i agents and carbohydrate restriction. Therefore, we studied these interactions using an obese diabetic animal model. KK‐A^y mice were pair‐fed normal chow [NC; carbohydrate: fat: protein = 65:15:20], low carbohydrate [LC; 43:42:15] or severely carbohydrate restricted diets [SR; 12:45:43] for 12 weeks. Tofogliflozin (Tofo) was administered as the SGLT2i in the NC and LC diet groups. Blood glucose levels were significantly increased in the SR group. Tofo reduced blood glucose levels significantly in the NC group during the experiment and in the LC group at 2‐6 weeks. Plasma triglycerides were markedly elevated in the SR group without Tofo, but decreased in response to Tofo administration. Hepatic triglyceride contents were not changed by the LC or the SR diet alone. However, Tofo ameliorated hepatosteatosis in NC‐fed animals. Consistent with the downregulation of stearoyl‐CoA desaturase 1, the ratio of plasma monounsaturated to saturated fatty acids was significantly reduced in the LC with Tofo and in the SR alone groups, but was not altered in the NC with Tofo group. In summary, metabolism of glucose and lipids was improved by Tofo but not by the SR diet. Furthermore, Tofo improved these parameters more effectively in the NC than in the LC diet group. These data suggest that the effects of SGLT2i are distinct from those of carbohydrate restriction and that a nonrestricted dietary carbohydrate composition is essential for SGLT2i treatment to be effective.

Hematological profile associated with type 2 diabetes mellitus

BACKGROUND

Hematological changes affecting blood cells and the coagulation factors are shown to be associated with diabetes mellitus. We investigated some of the hematological risk factors implicated in the development of type 2 diabetes mellitus.

METHODS

The study conducted in western Algeria on a sample of 1852 subjects, 1059 with type 2 diabetes and 793 witnesses, were evaluated for peripheral blood parameters using hematology analyzer. All the informations related to the disease were collected from the patients and recorded using predesigned questionnaire.

RESULTS

The logistic model retained, the mean corpuscular hemoglobin concentration reveals that subjects with concentration over the normal ratio (>36 g/dl) have an exposure risk six and half times higher than subjects with normal concentration (OR = 6.59; 95% CI = 2.51-17.31, P = 0.000). As regards to the platelets blood ratio, subjects with a ratio lower are five times more exposed to type 2 diabetes compared to subjects with a normal ratio (OR = 5.01; 95% CI = 1.78-14.13, P < 0.002). Our logistic model also retained basophils ratio (OR = 2.18; 95% CI = 1.35-3.53, P < 0.001) and sedimentation rate at one hour (OR = 7.83; 95% CI = 3.39-18.06, P = 0.000).

CONCLUSIONS

Hematological profile associated with type 2 diabetes mellitus retained the mean corpuscular hemoglobin concentration over the normal ratio, lower platelets blood ratio, basophils ratio and sedimentation rate at one hour.

Influence of Treatment with Extracts of Hypsyzigus marmoreus Mushroom on Body Composition during Obesity Development in KK-A(y) Mice

Hypsyzigus marmoreus (HM), an edible mushroom, has several effects, including antitumor, antioxidant and anti-allergy properties. On the other hand, the possibly useful effect of HM in diabetic mice has not as yet been elucidated. In this study, we showed treatment with a water soluble extract from HM (EHM) to reduce fat deposits without affecting body weight loss in KK-A(y) mice. EHM treatment also abolished the expressions of pro-inflammatory adipokines, such as tumor necrosis factor α and monocyte chemoattractant protein 1, as compared with vehicle treatment. The expressions of uncoupling protein 3 and peroxisome proliferator-activated receptor gamma coactivator 1α in the soleus muscles of EHM treatment groups were significantly elevated as compared to those in vehicle-treated muscle tissues. These results raise the possibility that EHM can regulate both obesity and insulin resistance.

Extracts of common buckwheat bran prevent sucrose digestion

Buckwheat has been shown to have various health benefits such as reduction of hypertension and improvement of hypercholesterolemia; however, its effect on diabetes has not been fully elucidated. In this study, buckwheat bran extracts (BBE) inhibited sucrase activity in vitro more effectively than buckwheat. Balb/c mice pretreated with BBE showed dose-dependent reductions of blood glucose, greater than those observed with control mice, within 60 min following oral sucrose administration. Blood glucose levels in mice pretreated with buckwheat extracts were also significantly lower compared to those in control mice within 30 min following oral administration of sucrose. However, rutin, one of the abundant polyphenols of BBE, did not lower blood glucose level. Our data indicate that components of BBE other than rutin have inhibitory activity against sucrase in vivo. These results suggest that BBE could have beneficial effects on diabetes.

Long-term treatment with hyperbaric air improves hyperlipidemia of db/db mice

Hyperbaric air (HBA) is used to improve healing of wounds including diabetic ulcer. The aim of this study was to clarify the effects of HBA exposure on lipid and glucose metabolism in db/db mice. HBA did not influence the weight of db/db mice. Serum levels of free fatty acid and triglyceride, but not glucose and insulin, were significantly decreased after 6 weeks of treatment with HBA. The mRNA expressions of CPT-1, PPARα and PGC-1α genes, which are related to lipid metabolism, were significantly up-regulated in the muscle and liver. Increases in TNFα and MCP1 mRNA, which impaired lipid metabolism, were also attenuated by HBA treatment. These results suggest that exposure of HBA could have beneficial effects on lipid metabolism in patients with type 2 diabetes mellitus.

A model of insulin resistance in mice, born to diabetic pregnancy, is associated with alterations of transcription-related genes in pancreas and epididymal adipose tissue

Objective. This study is conducted on a model of insulin-resistant (IR) mice born to dams which were rendered diabetic by the administration of streptozotocin. Methods. Adult IR and control offspring were selected and we determined the mRNA expression of transcription factors known to modulate pancreatic and adipose tissue activities and inflammation. Results. We observed that serum insulin increased, and the mRNA of insulin gene transcription factors, Pdx-1, Nkx6.1 and Maf-A, were upregulated in IR mice pancreas. Besides, their pancreatic functional capacity seemed to be exhausted as evidenced by low expression of pancreatic Glut2 and glucokinase mRNA. Though IR offspring exhibited reduced epididymal adipose tissue, their adipocytes seemed to be differentiated into macrophage-like cells, as they exhibited upregulated CD14 and CD68 antigens, generally expressed by macrophages. However, there was no peripheral macrophages infiltration into epididymal adipose tissue, as the expression of F4/80, a true macrophage marker, was undetectable. Furthermore, the expression of IL-6, TNF-α and TLR-2, key players of insulin resistance, was upregulated in the adipose tissue of IR offspring. Conclusion. Insulin resistant state in mice, born to diabetic pregnancy, alters the expression of function-related genes in pancreas and epididymal adipose tissue and these offspring are prone to develop metabolic syndrome.

Peroxisome proliferator-activated receptor-alpha modulates insulin gene transcription factors and inflammation in adipose tissues in mice

We have recently reported that PPAR alpha deficiency leads to hypoglycaemia and hypoinsulinemia in mice (Yessoufou et al. Endocrinology 147:4410-4418, 2006). Besides, these mice exhibited high adiposity with an inflammatory state. We, therefore, assessed, in this study, the effects of PPAR alpha deficiency on the expression of mRNA encoding for the insulin gene transcription factors in pancreatic beta-cells along with those implicated in inflammation in adipose tissues. On fasting, the adult PPAR alpha-null mice were hypoglycemic. Serum insulin concentrations and its pancreatic mRNA transcripts were downregulated in PPAR alpha-null mice, suggesting that PPAR alpha gene deletion contributes to low insulin gene transcription. The PPAR alpha gene deletion downregulates the mRNA expression of insulin gene transcription factors, i.e., Pdx-1, Nkx6.1, and MafA. Besides, the pancreatic function was diminished by PPAR alpha deficiency as PPAR alpha-null mice expressed low pancreatic Glut2 and glucokinase mRNA. PPAR alpha-null mice also expressed high adiponectin and leptin mRNA levels compared to wild type animals. Adipose tissues of PPAR alpha-null mice exhibited upregulation of CD14 and CD68 mRNA, generally expressed by macrophages. PPAR alpha gene deletion downregulates the adipocyte mRNA of certain pro-inflammatory agents, like MCP-1, TNF-alpha, IL-1 beta, IL-6, and RANTES, though pro-inflammatory TLR-2 and TLR-4 mRNAs were upregulated in the adipose tissues. Our results suggest that PPAR alpha deficiency, in mice, is implicated in the modulation of insulin gene transcription and inflammatory status in adipose tissues.

Traitement médicamenteux du diabète de type 2 (première partie)

Drug treatment of 2 diabetes is intended to normalize glycosylated hemoglobin levels (HbA(1c)<6.5%) and thereby prevent the development of micro- and macrovascular complications. Oral antidiabetic agents target the metabolic abnormalities that cause diabetes. The two principal families of oral antidiabetic agents - insulin sensitizers and insulin secretagogues - can be taken together. Thiazolidinediones or glitazones (insulin sensitizers) improve peripheral tissue sensitivity to insulin. Metformin (an insulin sensitizer) reduces hepatic glucose production. Sulfonylureas and meglitinides (insulin secretagogues) stimulate insulin secretion and can cause hypoglycemia. GLP-1 (Glucagon-Like Peptide-1) analogs and DPP-IV (dipeptidyl-peptidase-IV) inhibitors are new drug classes currently under development.