The etiology and pathogenesis of non-insulin-dependent diabetes

Effects of Treadmill Running at Different Light Cycles in Mice with Metabolic Disorders

Type 2 diabetes mellitus accounts for about 90% of cases of diabetes and is considered one of the most important problems of our time. Despite a significant number of studies on glucose metabolism, the molecular mechanisms of its regulation in health and disease remain insufficiently studied. That is why non-drug treatment of metabolic disorders is of great relevance, including physical activity. Metabolic changes under the influence of physical activity are very complex and are still difficult to understand. This study aims to deepen the understanding of the effect of physical exercise on metabolic changes in mice with diabetes mellitus. We studied the effect of forced treadmill running on body weight and metabolic parameters in mice with metabolic disorders. We developed a high-fat-diet-induced diabetic model of metabolic disorders. We exposed mice to forced treadmill running for 4 weeks. We determined glucose and insulin levels in the blood plasma biochemically and analyzed Glut-4 and citrate synthase in M. gastrocnemius muscle tissue using Western blotting. The research results show that daily treadmill running has different effects on different age groups of mice with metabolic disorders. In young-age animals, forced running has a more pronounced effect on body weight. At week 12, young obese mice had a 17% decrease in body weight. Body weight did not change in old mice. Moreover, at weeks 14 and 16, the decrease in body weight was more significant in the young mice (by 17%) compared to the old mice (by 6%) (p < 0.05). In older animals, it influences the rate of glucose uptake. At 60 min, the blood glucose in the exercised older mice decreased to 14.46 mmol/L, while the glucose concentration in the non-exercised group remained at 17 mmol/L. By 120 min, in mice subjected to exercise, the blood glucose approached the initial value (6.92 mmol/L) and amounted to 8.35 mmol/L. In the non-exercised group, this difference was 45%. The effects of physical activity depend on the time of day. The greater effect is observed when performing shift training or exercise during the time when animals are passive (light phase). In young mice, light phase training had a significant effect on increasing the content of Glut-4 in muscle tissue (84.3 ± 11.3%, p < 0.05 with control group-59.3 ± 7.8%). In aged mice, shift training caused an increase in the level of Glut-4 in muscle tissue (71.3 ± 4.1%, p < 0.05 with control group-56.4 ± 10,9%). In the group of aged mice, a lower CS level was noticed in all groups in comparison with young mice. It should also be noted that we observed that CS increased during exercise in the group of young mice, especially during light phase training. The CS content in the light phase subgroup (135.8 ± 7.0%) was higher than in the dark phase subgroup (113.3 ± 7.7%) (p = 0.0006). The CS decreased in aged chow-fed mice and increased in the high-fat-fed group. The CS content in the chow diet group (58.2 ± 5.0%) was 38% lower than in the HFD group (94.9 ± 8.8%).

Treadmill Training Effect on the Myokines Content in Skeletal Muscles of Mice With a Metabolic Disorder Model

The effect of treadmill training loads on the content of cytokines in mice skeletal muscles with metabolic disorders induced by a 16 week high fat diet (HFD) was studied. The study included accounting the age and biorhythmological aspects. In the experiment, mice were used at the age of 4 and 32 weeks, by the end of the experiment—respectively 20 and 48 weeks. HFD feeding lasted 16 weeks. Treadmill training were carried out for last 4 weeks six times a week, the duration 60 min and the speed from 15 to 18 m/min. Three modes of loading were applied. The first subgroup was subjected to stress in the morning hours (light phase); the second subgroup was subjected to stress in the evening hours (dark phase); the third subgroup was subjected to loads in the shift mode (the first- and third-weeks treadmill training was used in the morning hours, the second and fourth treadmill training was used in the evening hours). In 20-week-old animals, the exercise effect does not depend on the training regime, however, in 48-week-old animals, the decrease in body weight in mice with the shift training regime was more profound. HFD affected muscle myokine levels. The content of all myokines, except for LIF, decreased, while the concentration of CLCX1 decreased only in young animals in response to HFD. The treadmill training caused multidirectional changes in the concentration of myokines in muscle tissue. The IL-6 content changed most profoundly. These changes were observed in all groups of animals. The changes depended to the greatest extent on the training time scheme. The effect of physical activity on the content of IL-15 in the skeletal muscle tissue was observed mostly in 48-week-old mice. In 20-week-old animals, physical activity led to an increase in the concentration of LIF in muscle tissue when applied under the training during the dark phase or shift training scheme. In the HFD group, this effect was significantly more pronounced. The content of CXCL1 did not change with the use of treadmill training in almost all groups of animals. Physical activity, introduced considering circadian rhythms, is a promising way of influencing metabolic processes both at the cellular and systemic levels, which is important for the search for new ways of correcting metabolic disorders.

Chronic treatment with dapagliflozin protects against mitochondrial dysfunction in the liver of C57BL/6NCrl mice with high-fat diet/streptozotocin-induced diabetes mellitus

Dapagliflozin (DAPA), a selective inhibitor of sodium/glucose cotransporter SGLT2, is currently used as a hypoglycemic agent in the treatment of diabetes mellitus. In this work, we have assessed the effect of DAPA treatment (1 mg/kg/day) on the ultrastructure and functions of the liver mitochondria of C57BL/6NCrl mice with type 2 diabetes mellitus (T2DM) induced by a high-fat diet combined with low-dose streptozotocin injections. An electron microscopy study showed that DAPA prevented the mitochondrial swelling and normalized the average mitochondrial size in hepatocytes of diabetic animals. The treatment with DAPA reversed the decline in the mtDNA copy number in the liver of diabetic mice. DAPA-treated T2DM mice showed increased expression of the Ppargc1a, Mfn2 and Drp1 in the liver tissue. The treatment of diabetic animals with DAPA normalized the mitochondrial respiratory control ratio, significantly decreased the level of lipid peroxidation products in liver mitochondria, and decreased their resistance to the opening of the mitochondrial permeability transition pore. At the same time, DAPA had no effects on the studied parameters of control animals. The paper discusses the possible mechanisms of the effect of dapagliflozin on mitochondrial dysfunction in the liver of diabetic animals.

Duration of obesity exposure between ages 10 and 40 years and its relationship with cardiometabolic disease risk factors: A cohort study

BACKGROUND

Individuals with obesity do not represent a homogeneous group in terms of cardiometabolic risk. Using 3 nationally representative British birth cohorts, we investigated whether the duration of obesity was related to heterogeneity in cardiometabolic risk.

METHODS AND FINDINGS

We used harmonised body mass index (BMI) and cardiometabolic disease risk factor data from 20,746 participants (49.1% male and 97.2% white British) enrolled in 3 British birth cohort studies: the 1946 National Survey of Health and Development (NSHD), the 1958 National Child Development Study (NCDS), and the 1970 British Cohort Study (BCS70). Within each cohort, individual life course BMI trajectories were created between 10 and 40 years of age, and from these, age of obesity onset, duration spent obese (range 0 to 30 years), and cumulative obesity severity were derived. Obesity duration was examined in relation to a number of cardiometabolic disease risk factors collected in mid-adulthood: systolic (SBP) and diastolic blood pressure (DBP), high-density-lipoprotein cholesterol (HDL-C), and glycated haemoglobin (HbA1c). A greater obesity duration was associated with worse values for all cardiometabolic disease risk factors. The strongest association with obesity duration was for HbA1c: HbA1c levels in those with obesity for <5 years were relatively higher by 5% (95% CI: 4, 6), compared with never obese, increasing to 20% (95% CI: 17, 23) higher in those with obesity for 20 to 30 years. When adjustment was made for obesity severity, the association with obesity duration was largely attenuated for SBP, DBP, and HDL-C. For HbA1c, however, the association with obesity duration persisted, independent of obesity severity. Due to pooling of 3 cohorts and thus the availability of only a limited number harmonised variables across cohorts, our models included adjustment for only a small number of potential confounding variables, meaning there is a possibility of residual confounding.

CONCLUSIONS

Given that the obesity epidemic is characterised by a much earlier onset of obesity and consequently a greater lifetime exposure, our findings suggest that health policy recommendations aimed at preventing early obesity onset, and therefore reducing lifetime exposure, may help reduce the risk of diabetes, independently of obesity severity. However, to test the robustness of our observed associations, triangulation of evidence from different epidemiological approaches (e.g., mendelian randomization and negative control studies) should be obtained.

The Effect of S-15176 Difumarate Salt on Ultrastructure and Functions of Liver Mitochondria of C57BL/6 Mice with Streptozotocin/High-Fat Diet-Induced Type 2 Diabetes

Simple Summary

Type II diabetes mellitus (T2DM) is one of the most common diseases, which currently represents a major medical and social problem due to the chronic course, high rates of disability and mortality among patients. Mitochondria of the liver and other vital organs are one of the main targets of T2DM at the intracellular level. The pathological changes in the structure of mitochondria, hyperproduction of reactive oxygen species by the organelles, disorders in mitochondrial transport systems and ATP synthesis are now widely recognized as important factors in the development of diabetes. Therefore, treatment strategies to attenuate mitochondrial injury may result in cellular reprogramming and alleviation of the diabetes-related pathological complications. The aim of present work was to investigate the possible protective effect of S-15176, a potent derivative of the anti-ischemic agent trimetazidine, against mitochondrial damage in the liver of mice with experimental T2DM. The data indicate that S-15176 attenuates mitochondrial dysfunction and ultrastructural abnormalities in the liver of T2DM mice. The mechanisms underlying the protective effect of S-15176 are related to the stimulation of mitochondrial biogenesis and the inhibition of lipid peroxidation in the organelles. One may assume that the compound acts as a mitochondria-targeted metabolic reprogramming agent in T2DM.

Abstract

S-15176, a potent derivative of the anti-ischemic agent trimetazidine, was reported to have multiple effects on the metabolism of mitochondria. In the present work, the effect of S-15176 (1.5 mg/kg/day i.p.) on the ultrastructure and functions of liver mitochondria of C57BL/6 mice with type 2 diabetes mellitus (T2DM) induced by a high-fat diet combined with a low-dose streptozotocin injection was examined. An electron microscopy study showed that T2DM induced mitochondrial swelling and a reduction in the number of liver mitochondria. The number of mtDNA copies in the liver in T2DM decreased. The expression of Drp1 slightly increased, and that of Mfn2 and Opa1 somewhat decreased. The treatment of diabetic animals with S-15176 prevented the mitochondrial swelling, normalized the average mitochondrial size, and significantly decreased the content of the key marker of lipid peroxidation malondialdehyde in liver mitochondria. In S-15176-treated T2DM mice, a two-fold increase in the expression of the PGC-1α and a slight decrease in Drp 1 expression in the liver were observed. The respiratory control ratio, the level of mtDNA, and the number of liver mitochondria of S-15176-treated diabetic mice tended to restore. S-15176 did not affect the decrease in expression of Parkin and Opa1 in the liver of diabetic animals, but slightly suppressed the expression of these proteins in the control. The modulatory effect of S-15176 on dysfunction of liver mitochondria in T2DM can be related to the stimulation of mitochondrial biogenesis and the inhibition of lipid peroxidation in the organelles.

Diabetes Mellitus, Mitochondrial Dysfunction and Ca2+-Dependent Permeability Transition Pore

Diabetes mellitus is one of the most common metabolic diseases in the developed world, and is associated either with the impaired secretion of insulin or with the resistance of cells to the actions of this hormone (type I and type II diabetes, respectively). In both cases, a common pathological change is an increase in blood glucose—hyperglycemia, which eventually can lead to serious damage to the organs and tissues of the organism. Mitochondria are one of the main targets of diabetes at the intracellular level. This review is dedicated to the analysis of recent data regarding the role of mitochondrial dysfunction in the development of diabetes mellitus. Specific areas of focus include the involvement of mitochondrial calcium transport systems and a pathophysiological phenomenon called the permeability transition pore in the pathogenesis of diabetes mellitus. The important contribution of these systems and their potential relevance as therapeutic targets in the pathology are discussed.

Diabetes-Induced Dysfunction of Mitochondria and Stem Cells in Skeletal Muscle and the Nervous System

Diabetes mellitus is one of the most common metabolic diseases spread all over the world, which results in hyperglycemia caused by the breakdown of insulin secretion or insulin action or both. Diabetes has been reported to disrupt the functions and dynamics of mitochondria, which play a fundamental role in regulating metabolic pathways and are crucial to maintain appropriate energy balance. Similar to mitochondria, the functions and the abilities of stem cells are attenuated under diabetic condition in several tissues. In recent years, several studies have suggested that the regulation of mitochondria functions and dynamics is critical for the precise differentiation of stem cells. Importantly, physical exercise is very useful for preventing the diabetic alteration by improving the functions of both mitochondria and stem cells. In the present review, we provide an overview of the diabetic alterations of mitochondria and stem cells and the preventive effects of physical exercise on diabetes, focused on skeletal muscle and the nervous system. We propose physical exercise as a countermeasure for the dysfunction of mitochondria and stem cells in several target tissues under diabetes complication and to improve the physiological function of patients with diabetes, resulting in their quality of life being maintained.

Treadmill running induces satellite cell activation in diabetic mice

Skeletal muscle-derived stem cells, termed as satellite cells, play essential roles in regeneration after muscle injury in adult skeletal muscle. Diabetes mellitus (DM), one of the most common metabolic diseases, causes impairments of satellite cell function. However, the studies of the countermeasures for the DM-induced dysfunction of satellite cells have been poor. Here, we investigated the effects of chronic running exercise on satellite cell activation in diabetic mice focused on the molecular mechanism including Notch and Wnt signaling, which are contribute to the fate determination of satellite cells. Male C57BL/6 mice 4 weeks of age were injected with streptozotocin and were randomly divided into runner group and control group. Runner group mice were performed treadmill running for 4 weeks. DM attenuated satellite cell activation and the expressions of the components of Notch and Wnt signaling. However, chronic running resulted in activation of satellite cells in diabetic mice and salvaged the inactivity of Wnt signaling but not Notch signaling. Our results suggest that chronic running induces satellite cell activation via upregulation of Wnt signaling in diabetic as well as normal mice.

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Diabetes attenuates satellite cell activation.

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Diabetes downregulates the activities of Notch and Wnt signaling.

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Treadmill running activates satellite cells in diabetic mice.

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Treadmill running can salvage diabetes-induced downregulation of Wnt signaling.

Diabetes and stem cell function

Diabetes mellitus is one of the most common serious metabolic diseases that results in hyperglycemia due to defects of insulin secretion or insulin action or both. The present review focuses on the alterations to the diabetic neuronal tissues and skeletal muscle, including stem cells in both tissues, and the preventive effects of physical activity on diabetes. Diabetes is associated with various nervous disorders, such as cognitive deficits, depression, and Alzheimer's disease, and that may be caused by neural stem cell dysfunction. Additionally, diabetes induces skeletal muscle atrophy, the impairment of energy metabolism, and muscle weakness. Similar to neural stem cells, the proliferation and differentiation are attenuated in skeletal muscle stem cells, termed satellite cells. However, physical activity is very useful for preventing the diabetic alteration to the neuronal tissues and skeletal muscle. Physical activity improves neurogenic capacity of neural stem cells and the proliferative and differentiative abilities of satellite cells. The present review proposes physical activity as a useful measure for the patients in diabetes to improve the physiological functions and to maintain their quality of life. It further discusses the use of stem cell-based approaches in the context of diabetes treatment.

The role of insulin resistance in the pathogenesis of atherosclerotic cardiovascular disease: an updated review

Insulin resistance is the main pathologic mechanism that links the constellation of clinical, metabolic and anthropometric traits with increased risk for cardiovascular disease and type II diabetes mellitus. These traits include hyperinsulinemia, impaired glucose intolerance, endothelial dysfunction, dyslipidemia, hypertension, and generalized and upper body fat redistribution. This cluster is often referred to as insulin resistance syndrome. The progression of insulin resistance to diabetes mellitus parallels the progression of endothelial dysfunction to atherosclerosis leading to cardiovascular disease and its complications. In fact, insulin resistance assessed by homeostasis model assessment (HOMA) has shown to be independently predictive of cardiovascular disease in several studies and one unit increase in insulin resistance is associated with a 5.4% increase in cardiovascular disease risk. This review article addresses the role of insulin resistance as a main causal factor in the development of metabolic syndrome and endothelial dysfunction, and its relationship with cardiovascular disease. In addition to this, we review the type of lifestyle modification and pharmacotherapy that could possibly ameliorate the effect of insulin resistance and reverse the disturbances in insulin, glucose and lipid metabolism.

The duration of obesity and the risk of type 2 diabetes

Objective

The evidence for the association between obesity and the risk of type 2 diabetes has been derived mainly from the analysis of the degree of obesity. The role of the duration of obesity as an independent risk has not been fully explored. The objective of the present study was to investigate the association between the duration of obesity and the risk of type 2 diabetes.

Design

Prospective cohort study.

Setting

The Framingham Heart Study (FHS), follow-up from 1948 to 1998.

Subjects

A total of 1256 FHS participants who were free from type 2 diabetes at baseline, but were obese on at least two consecutive of the study’s twenty-four biennial examinations, were included. Type 2 diabetes status was collected throughout the 48 years of follow-up of the study. The relationship between duration of obesity and type 2 diabetes was analysed using time-dependent Cox models, adjusting for a number of covariates.

Results

The unadjusted hazard ratio (HR) for the risk of type 2 diabetes for men was 1·13 (95 % CI 1·09, 1·17) and for women was 1·12 (95 % CI 1·08, 1·16) per additional 2-year increase in the duration of obesity. Adjustment for sociodemographic variables, family history of diabetes, health behaviour and physical activity made little difference to these HR. For women the evidence of a dose–response relationship was less clear than for men, particularly for women with an older age at obesity onset.

Conclusions

The duration of obesity is a relevant risk factor for type 2 diabetes, independent of the degree of BMI.

Congenital and environmental factors associated with adipocyte dysregulation as defects of insulin resistance

The metabolic syndrome refers to insulin resistance and its associated cluster of related cardiovascular metabolic risk factors including type 2 diabetes, hypertension, dyslipidemia and central obesity. Although many hypotheses and facts have been proposed to explain the interaction between genetic and environmental causes of this syndrome, the primary etiology of the metabolic syndrome is adipose tissue dysregulation. Firstly, the thrifty genotype and phenotype hypothesis may explain the endemic increase in type 2 diabetes and cardiovascular disease in developing countries and elucidates the congenital susceptibility and environmental triggering of the metabolic syndrome. Secondly, over-nutrition leads to fatty acid (FA) accumulation in adipocytes and to an overflow to ectopic fat storage organs. This causes functional changes in adipocytes shifting the intra-cellular metabolic pathway toward insulin resistance. Thirdly, obese subjects exhibit increased fat cell size and over-secretion of biologic adipocytokines. Fourthly, failure to adequately develop adipose tissue mass, as seen in lipodystrophy cases, causes severe insulin resistance and diabetes. Lastly, similar to human type 2 diabetes, Psammonys obesus, a desert rat which feeds mainly on low-calorie vegetation, develops the metabolic syndrome when given a diet of calorie rich food. The above evidence indicates adipocyte dysregulation and secretion of FA as well as certain molecules from overloaded adipocytes/adipokines contribute to the pathogenesis of impaired insulin secretion and insulin resistance, endothelial dysfunction, a pro-inflammatory state and promote progression of atherosclerosis. The metabolic syndrome is a modern disease resulting adipocyte dysmetabolism resulting from the paradox of the slow human evolution combined with rapid environmental changes.

The metabolic effects of long term exercise in Type 2 Diabetes patients

INTRODUCTION

The effectiveness of physical exercise in the management of diabetes mellitus type 2 is well established. The purpose of this investigation was to evaluate the effect of long term exercise on glycemic and metabolic control measured after eight months in contrast to patients who had ceased their training after four months.

METHODS

After an effective 4 months' strength training or endurance training period, ten patients (5 male and 5 female, mean age +/- SE:57.1 +/- 1.6 yr) were randomised to a further 4 months of combined endurance and strength training, while a control group of 10 patients (5 male and 5 female, mean age +/- SE:56.9 +/- 1.6 yr) ceased training.

RESULTS

Long term glycemic control improved and HbA1C values fell from 6.9 +/- 0.4 to 6.2 +/- 0.2 in active patients and increased from 7.5 +/- 0.4 to 8.7 +/- 0.6 in control patients (p = 0.002). Baseline levels of total cholesterol significantly decreased in training group (205.5 mg/dl +/- 14.1 to 177.5 +/- 13.3) and increased in controls (185.9 +/- 14.1 to 220.2 +/- 15.8) [p = 004]. In addition, significant decreases in LDL-cholesterol and triglyceride levels (both p < 05) were observed in the training group compared to controls.

CONCLUSION

This study showed that in addition to a 4 month training period, continuation of training proved highly beneficial with further reductions in fasting blood glucose, HbA1C, total cholesterol, LDL-cholesterol, triglyceride, and an elevation in HDL-cholesterol concentrations in diabetes mellitus type 2 patients, thus resulting in a reduced atherogenic lipid profile. In contrast, patients who ceased training after 4 months developed an atherogenic lipid profile and a worsened glycemic control. The results of this study indicate that long term exercise plays an important role in the treatment of diabetes mellitus type 2 and may protect against the development of cardiovascular diseases.

The relative benefits of endurance and strength training on the metabolic factors and muscle function of people with type 2 diabetes mellitus

OBJECTIVE

To compare the effects of a 4-month strength training (ST) versus aerobic endurance training (ET) program on metabolic control, muscle strength, and cardiovascular endurance in subjects with type 2 diabetes mellitus (T2D).

DESIGN

Randomized controlled trial.

SETTING

Large public tertiary hospital.

PARTICIPANTS

Twenty-two T2D participants (11 men, 11 women; mean age +/- standard error, 56.2+/-1.1 y; diabetes duration, 8.8+/-3.5 y) were randomized into a 4-month ST program and 17 T2D participants (9 men, 8 women; mean age, 57.9+/-1.4 y; diabetes duration, 9.2+/-1.7 y) into a 4-month ET program.

INTERVENTIONS

ST (up to 6 sets per muscle group per week) and ET (with an intensity of maximal oxygen consumption of 60% and a volume beginning at 15 min and advancing to a maximum of 30 min 3x/wk) for 4 months.

MAIN OUTCOME MEASURES

Laboratory tests included determinations of blood glucose, glycosylated hemoglobin (Hb A1c), insulin, and lipid assays.

RESULTS

A significant decline in Hb A1c was only observed in the ST group (8.3%+/-1.7% to 7.1%+/-0.2%, P=.001). Blood glucose (204+/-16 mg/dL to 147+/-8 mg/dL, P<.001) and insulin resistance (9.11+/-1.51 to 7.15+/-1.15, P=.04) improved significantly in the ST group, whereas no significant changes were observed in the ET group. Baseline levels of total cholesterol (207+/-8 mg/dL to 184+/-7 mg/dL, P<.001), low-density lipoprotein cholesterol (120+/-8 mg/dL to 106+/-8 mg/dL, P=.001), and triglyceride levels (229+/-25 mg/dL to 150+/-15 mg/dL, P=.001) were significantly reduced and high-density lipoprotein cholesterol (43+/-3 mg/dL to 48+/-2 mg/dL, P=.004) was significantly increased in the ST group; in contrast, no such changes were seen in the ET group.

CONCLUSIONS

ST was more effective than ET in improving glycemic control. With the added advantage of an improved lipid profile, we conclude that ST may play an important role in the treatment of T2D.

Bivariate genetic analysis of fasting insulin and glucose levels

The main aim of this study was to estimate the relative influence of genes and environment on fasting insulin levels, which were considered a proxy of insulin resistance. Possible sex differences in genetic and environmental influences, and the origin of the covariance between fasting insulin and glucose were investigated. Subjects were 209 pairs of middle-aged twins, divided into 5 sex-by-zygosity groups. A general bivariate model and a reciprocal causation model including fasting insulin and glucose were used in the analyses. For both quantitative genetic models, a model specifying additive genetic and unique environmental factors, which were the same in males and females, showed the best fit to the data. Heritability estimates were modest and highly similar in both models: 20-25% of the variance in fasting insulin, and around 50% of the variance in fasting glucose levels could be attributed to genetic factors. The two models could not be discriminated on the basis of their fit to the data. A submodel of the general bivariate model suggested that the covariance between glucose and insulin has a unique environmental basis, whereas for the reciprocal causation model both causal paths were needed to explain the phenotypic correlation between insulin and glucose and estimates of the reciprocal paths were of opposite sign, an indication for the expected negative feedback loop.

Peripheral tissue glucose uptake is not reduced after an oral glucose load in Southern Italian subjects at risk of developing non-insulin-dependent diabetes mellitus

Studies searching for the inherited defects that cause non-insulin-dependent diabetes mellitus (NIDDM) have been performed mostly in Northern European subjects using the hyperinsulinemic clamp technique. The conclusion drawn from most of these studies is that peripheral insulin resistance is likely a primary inherited defect. Our aim was to examine early defects in glucose metabolism using a more physiological technique in a different ethnic group. For this, a double-label oral glucose tolerance test (OGTT) was performed in young diabetes-prone Southern Italian subjects who had both parents with NIDDM (relatives) and in subjects with no family history of NIDDM (matched for age, weight, and ethnicity). Fasting plasma glucose and insulin in the relatives were normal; however, they had impaired glucose tolerance during the OGTT. This was due to reduced hepatic glucose uptake (17.9+/-2.8 v. 28.1+/-2.3 g, P<.02). No defects were found in the metabolic clearance rate (MCR) of glucose or endogenous glucose production. During an intravenous glucose tolerance test (IVGTT), insulin sensitivity was again found to be normal (3.04+/-0.65 in relatives v. 2.33+/-0.38 min(-1) per micromol x L(-1) x min in controls), with a marked reduction in first-phase insulin secretion in the relatives (110+/-12 v. 211+/-18 pmol x L(-1) x min per mmol x L(-1), P<.001). A strong correlation was found between hepatic glucose uptake and insulin secretion (r = .81, P<.001), which may suggest that the same abnormality operates in both the liver and pancreas. Therefore, the metabolic defect that causes hyperglycemia in diabetes-prone subjects is not always a reduced peripheral insulin sensitivity. The genetic basis of NIDDM may differ between different ethnic groups.

The effect of coenzyme Q10 administration on metabolic control in patients with type 2 diabetes mellitus

A possible relationship between the pathogenesis of type 2 diabetes and coenzyme Q10 (CoQ10) deficiency has been proposed. The aim of this study was to assess the effect of CoQ10 on metabolic control in 23 type 2 diabetic patients in a randomized, placebo-controlled trial. Treatment with CoQ10 100 mg bid caused a more than 3-fold rise in serum CoQ10 concentration (p < 0.001). No correlation was observed between serum CoQ10 concentration and metabolic control. No significant changes in metabolic parameters were observed during CoQ10 supplementation. The treatment was well tolerated and did not interfere with glycemic control, therefore CoQ10 may be used as adjunctive therapy in patients with associated cardiovascular diseases.

Non-insulin-dependent diabetes mellitus in childhood and adolescence

NIDDM in children and adolescents represents a heterogeneous group of disorders with different underlying pathophysiologic mechanisms. Most subtypes of NIDDM that occur in childhood are uncommon, but some, such as early onset of "classic" NIDDM, seem to be increasing in prevalence. This observed increase is thought to be caused by societal factors that lead to sedentary lifestyles and an increased prevalence of obesity. In adults, hyperglycemia frequently exists for years before a diagnosis of NIDDM is made and treatment is begun. Microvascular complications, such as retinopathy, are often already present at the time of diagnosis. Children are frequently asymptomatic at the time of diagnosis, so screening for this disorder in high-risk populations is important. Screening should be considered for children of high-risk ethnic populations with a strong family history of NIDDM with obesity or signs of hyperinsulinism, such as acanthosis nigricans. Even for children in these high-risk groups who do not yet manifest hyperglycemia, primary care providers can have an important role in encouraging lifestyle modifications that might delay or prevent onset of NIDDM.

Profactor-H (elevated circulating insulin): the link to health risk factors and diseases of civilization

We propose the term Profactor-H for chronic elevated circulating insulin. Profactor-H is common in atherosclerosis, essential hypertension, non-insulin dependent diabetes mellitus, some forms of obesity, some forms of cancer, cardiovascular disease, peripheral vascular disease and some forms of stroke. Profactor-H appears to be the central pathophysiologic consideration in the etiology of many diseases and health risk factors. Profactor-H's impact depends on genetic predisposition, frequency consumption of refined simple and complex carbohydrates, deficiency in dietary chromium, sedentary life style and stresses of modern day living. In many obese individuals, Profactor-H disturbs metabolic balance, favoring anabolic metabolism, and is exacerbated through chronic insulin production and impairment of insulin action. This vicious cycle also appears to be common in many apparently healthy, non-obese individuals destined to develop health risks and diseases in response to long-term adverse consequences of Profactor-H. We believe that a four-pronged program which 1) reduces the daily frequency of carbohydrate consumption, particularly refined foods and simple sugars, 2) supplements the daily dietary intake of chromium, 3) encourages activity, and 4) reduces stress, will minimize the impact of Profactor-H and thereby reduce health risks and result in improved health.

The low birth weight hypothesis as a plausible explanation for the black/white differences in hypertension, non-insulin-dependent diabetes, and end-stage renal disease

It is well known that black Americans have a higher risk for low birth weight (LBW) than white Americans. In addition, blacks are at a higher risk for hypertension (HT), non-insulin dependent diabetes mellitus (NIDDM), and end-stage renal disease (ESRD), particularly ESRD attributed to HT (ESRD-HT) and NIDDM (ESRD-NIDDM). It has been shown that LBW is associated with postpartum anatomic and functional alterations in the kidney and pancreas as well as with progressive renal damage in animals and increased risk for HT and NIDDM during adulthood in humans. Based on these empirical findings, it is here proposed that a greater risk of HT, NIDDM, and ESRD, particularly ESRD-HT and ESRD-NIDDM, in black Americans during adulthood may be partly related to their higher risk of LBW. However, LBW is proposed here as a component factor rather than a sufficient cause or a necessary factor for the development of these diseases. The ultimate contribution of LBW to the black/white disparities regarding HT, NIDDM, and ESRD may depend not only on the black/white differences in LBW but also on the race-specific prevalences of other component factors, both environmental/behavioral and genetic, that may or may not require the presence of LBW to cause each of these diseases.

Disordered metabolism in diabetes: have we underemphasized the fat component?

Despite intensive investigation, a clear understanding of the metabolic disturbances in diabetes mellitus and their temporal relationship to each other during disease development has still not emerged. With emphasis on non-insulin-dependent diabetes (NIDDM), three possibilities are explored here: (1) that the insulin resistance characteristic of obesity/NIDDM syndromes is the result rather than the cause of hyperinsulinemia, as is widely held, (2) that the linkage between hyperactivity of the pancreatic beta-cell and peripheral insulin resistance is vested in excessive delivery of lipid substrate from liver to the muscle bed, and (3) the conceivably hyperamylinemia works in concert with hyperinsulinemia in promoting overproduction of very-low-density lipoproteins by the liver, and thus in the etiology of muscle insulin resistance.