Microvascular complications of impaired glucose tolerance

Buccal spray insulin in subjects with impaired glucose tolerance: the prevoral study

AIM

Postprandial hyperglycaemia is a consequence of reduced first phase insulin response and is associated with increased cardiovascular risk and mortality. The aim of this proof-of-concept study was to investigate the safety and efficacy of treatment with buccal spray insulin (Oral-lyn™, Generex Biotechnology Corporation, Toronto, Ontario, Canada) on postprandial plasma glucose and insulin levels in subjects with impaired glucose tolerance (IGT).

METHODS

A total of 19 female and 12 male Caucasian subjects, 52.2 ± 13.5 (SD) years old, having a body mass index of 33.1 ± 6 (SD) kg/m² with confirmed IGT were included in the study. Subjects were randomized to take 4, 6 or 12 Oral-lyn puffs (1 puff = 1 s.c. rapid insulin UI) split into two equal doses each, one before and the second 30 min after a standard 75 g oral glucose tolerance test (OGTT). Glucose and insulin levels were measured at baseline and 30, 60, 90, 120 and 180 min afterwards.

RESULTS

Glucose fluctuations during OGTT were not modified by 4 or 6 Oral-lyn puffs. Treatment with 12 puffs was followed by 29.6% decrease in plasma glucose at 2 h and 26.8% decrease at 3 h, altogether p = 0.01. Considering all time points of the OGTT, there was a mean reduction of 15.8% in glucose levels. With 6 of the total 12 puffs used in group C there was a significant increase in the insulin levels during OGTT at 30 min (p < 0.04) but not at 2 or 3 h. No hypoglycaemic episodes were observed at any time points of the OGTT.

CONCLUSIONS

This proof-of-concept study demonstrates that treatment with buccal spray insulin is a simple and valuable therapy for reducing postprandial hyperglycaemia in obese subjects with IGT. Importantly, this treatment is safe and none of the study subjects experienced hypoglycaemia.

Bell's palsy: a manifestation of prediabetes?

BACKGROUND

Idiopathic peripheral facial nerve palsy or Bell's palsy (BP) is the most common cause of facial nerve palsy.

OBJECTIVE

To evaluate the role of glucose metabolism abnormalities in BP.

METHODS

We identified 148 patients with unilateral BP and 128 control subjects. In all we evaluated glucose level at fasting and after a 2-h oral glucose tolerance test (2h-OGTT). In addition we determined insulin resistance (IR), by HOMA-index. Patients and controls were divided in to two groups, according to their Body Mass Index (BMI).

RESULTS

Following a 2h-OGTT, the prevalence of glucose metabolism abnormalities was significantly higher in patients with BP than in controls (P < 0.001). Impaired glucose tolerance (IGT) was found in 57 (38%) patients and in 23 (18%) controls, while a new-diagnosed DM (NDDM) was found in 29 (19%) patients and in 8 (6%) controls. The IR was significantly increased only in BP patients with BMI ≥ 24.9 (P = 0.005). BMI, waist circumference, blood pressure, tryglicerides, serum lipid, drugs use were not significantly different between patients and controls.

CONCLUSIONS

In this study we found that prediabetes is frequently associated with facial palsy. We propose to perform a 2h-OGTT in patients with peripheral facial palsy and normal fasting glycaemia. HOMA-index should be evaluated in obese facial palsy patients.

Early microvascular complications of prediabetes in mice with impaired glucose tolerance and dyslipidemia

Microvascular complications are an important cause of morbidity in diabetic patients and can be detected in a significant number of patients at the time of diabetes diagnosis. However, little is known about the alterations in the microvasculature previous to the clinical manifestation of diabetes mellitus type 2. To obtain more insights into the early microvascular deterioration resulting from prediabetes, morphological and functional microvascular parameters were monitored using intravital fluorescence microscopy through a dorsal skin-fold chamber preparation in the uncoupling promotor-driven diphtheria toxin A chain (UCP1/DTA) mice. At the age of 12 weeks, the UCP1/DTA-mice were characterized by impaired glucose tolerance with concurrent unchanged fasting glucose, as well as dyslipidemia, hyperinsulinemia, hypertension and obesity. Prediabetic mice displayed combined hypertriglyceridemia and hypercholesterinemia. Associated with these prediabetic metabolic alterations, we demonstrate that microvascular density showed a dramatic decrease due to a reduction in perfused small vessels. A reduction in vascular density combined with unaltered blood flow in single vessels resulted in impaired tissue perfusion. Endothelial dysfunction with subsequently increased microvascular permeability and leukocyte-endothelium interactions were found. Our results of profound microvascular alterations at stages of normal fasting glucose underline the importance of early screening for prediabetes and associated microvascular complications.

Exercise and type 2 diabetes: the American College of Sports Medicine and the American Diabetes Association: joint position statement

Although physical activity (PA) is a key element in the prevention and management of type 2 diabetes, many with this chronic disease do not become or remain regularly active. High-quality studies establishing the importance of exercise and fitness in diabetes were lacking until recently, but it is now well established that participation in regular PA improves blood glucose control and can prevent or delay type 2 diabetes, along with positively affecting lipids, blood pressure, cardiovascular events, mortality, and quality of life. Structured interventions combining PA and modest weight loss have been shown to lower type 2 diabetes risk by up to 58% in high-risk populations. Most benefits of PA on diabetes management are realized through acute and chronic improvements in insulin action, accomplished with both aerobic and resistance training. The benefits of physical training are discussed, along with recommendations for varying activities, PA-associated blood glucose management, diabetes prevention, gestational diabetes mellitus, and safe and effective practices for PA with diabetes-related complications.

Prediabetes as a therapeutic target

BACKGROUND

The term "prediabetes" is used to describe a condition that involves impaired glucose tolerance (IGT) or impaired fasting glucose (IFG). IGT is defined by a 2-h oral glucose tolerance test plasma glucose concentration >140 mg/dL (7.8 mmol/L) but <200 mg/dL (11.1 mmol/L), and IFG is defined by a fasting plasma glucose concentration ≥100 mg/dL (5.6 mmol/L), but <126 mg/dL (7.0 mmol/L). Studies have shown that people with prediabetes tend to develop type 2 diabetes within 10 years and are at increased risk for cardiovascular disease and death even before the development of diabetes.

CONTENT

In this minireview we discusses the epidemiology, pathophysiology, and clinical implications of prediabetes. The rationale for therapeutic intervention in people with prediabetes, the goals of intervention, and the specific tools for intervention are presented. Emphasis is placed on data from randomized controlled clinical trials, whenever such data are available.

SUMMARY

Approximately 57 million Americans have prediabetes and are consequently at risk for cardiometabolic complications. Lifestyle modifications (dietary restriction and exercise) and certain medications can prevent the development of diabetes in persons with prediabetes. Lifestyle intervention also has been demonstrated to decrease cardiovascular disease risk markers, although data on clinical events are lacking.

Waist circumference leads to prolonged microvascular reactive hyperemia response in young overweight/obese women

OBJECTIVES

Previous data in our laboratory have shown microvascular dysfunction in normoglycaemic subjects with metabolic syndrome (MS). In a step further, we have investigated which clinical parameters related or not to MS would elicit microvascular dysfunction and the need of diagnosing MS for the establishment of microcirculatory impairment in overweight/obese women.

METHODS

Nineteen lean [23.6±3.1years, body mass index (BMI) 21.9±1.8kg/m(2)] and 59 overweight/obese [24.6±3.7years; BMI 34.4±5.9kg/m(2)] sedentary non-smoking women, divided in overweight/obese without (MS negative, n=36) and obese with MS (MS positive, n=23) were evaluated. Blood biochemistry, HOMA-IR index and anthropometric variables were determined. Morphological (capillary diameters) and functional [functional capillary density, red blood cell velocity (RBCV) at baseline and peak and time (TRBCV(max)) to reach it during post-occlusive reactive hyperemia after 1min ischemia] microcirculatory variables were examined by nailfold videocapillaroscopy.

RESULTS

Compared to controls, overweight/obese MS negative and obese MS positive presented longer TRBCV(max); the presence of two MS components was sufficient to prolong it and the MS diagnosis did not add any significant impairment to the microcirculation. Among clinical parameters investigated, a direct relationship between TRBCV(max) and waist circumference and insulin concentrations was found.

CONCLUSION

Our results have shown that microvascular dysfunction is independent of metabolic syndrome diagnosis and could be predicted by the waist circumference on young overweight/obese women, reinforcing the relationship between obesity-related microvascular/metabolic disturbances.

Pathogenesis of the hyperlipidemia of Gram-negative bacterial sepsis may involve pathomorphological changes in liver sinusoidal endothelial cells

The Gram-negative bacterium Pseudomonas aeruginosa is one of the most common opportunistic pathogens, especially after liver transplantation. Pathophysiological alterations of liver sinusoidal endothelial cells (LSECs) have far-reaching repercussions on the liver and on metabolism. LSECs are perforated with fenestrations, pores that facilitate the transfer of lipoproteins and macromolecules between blood and hepatocytes. Gram-negative bacterial endotoxin (lipopolysaccharide, LPS) and the P. aeruginosa toxin, pyocyanin, have marked effects on LSECs. Initial loss of LSEC porosity (defenestration) induced by P. aeruginosa pyocyanin and LPS may confer subsequent immune tolerance to circulating bacterial antigens and toxins. This review collates the known immune responses of the liver to Gram-negative bacterial toxins, with a focus on LSECs. Hyperlipidemia is an important response to Gram-negative bacterial sepsis. The mechanisms proposed for sepsis-associated hyperlipidemia include tissue lipoprotein lipase inhibition and upregulated hepatic triglyceride production. In this review, we propose defenestration of the LSECs by bacterial toxins as an additional mechanism for the hyperlipidemia of sepsis. Given the role of LSECs in hyperlipidemia and liver allograft rejection, LSEC changes induced by P. aeruginosa toxins including LPS and pyocyanin may have significant clinical implications.

Involvement of osteopontin upregulation on mesangial cells growth and collagen synthesis induced by intermittent high glucose

Glucose fluctuations are strong predictor of diabetic vascular complications. We explored the effects of constant and intermittent high glucose on the proliferation and collagen synthesis of cultured rat mesangial cells. Furthermore, the possible involvement of osteopontin (OPN) was assessed. In rat mesangial cells cultured in 5, 25, or 5 mmol/L alternating with 25 mmol/L glucose in the absence or presence of neutralizing antibodies to OPN, beta3 integrin receptor and beta5 integrin receptor, the cell proliferation, collagen synthesis, and the expression of OPN and type IV collagen were assessed. In cultured mesangial cells, treatment with constant or intermittent high glucose significantly increased [(3)H]thymidine incorporation in a time-dependent manner. A modest increase was observed at 12 h, and further deteriorated afterwards, and reached the maximum incorporation at 48 h. Treatment with constant high glucose for 48 h resulted in significant increases in [(3)H]thymidine incorporation, cell number, [(3)H]proline incorporation, mRNA, and protein levels of type IV collagen and OPN compared with mesangial cells treated with the normal glucose, which were markedly enhanced in cells exposed to intermittent high glucose medium. In addition, neutralizing antibodies to either OPN or its receptor beta3 integrin but not neutralizing antibodies to beta5 integrin can effectively prevented proliferation and collagen synthesis of mesangial cells induced by constant or intermittent high glucose. Intermittent high glucose exacerbates mesangial cells growth and collagen synthesis by upregulation of OPN expression, indicating that glycemic variability have important pathological effects on the development of diabetic nephropathy, which is mediated by the stimulation of OPN expression and synthesis.

Intermittent high glucose enhances cell proliferation and VEGF expression in retinal endothelial cells: the role of mitochondrial reactive oxygen species

Proliferation of human retinal endothelial cells (HRECs) is an important event in the development of diabetic retinopathy. Glucose fluctuations are strong predictor of diabetic vascular complications. In this study we have investigated the effect of intermittent high glucose on proliferation and expression of vascular endothelial growth factor (VEGF) in HRECs. The possible involvement of mitochondrial reactive oxygen species (ROS) was assessed. HRECs were incubated for 72 h in media containing different glucose concentrations: 5, 25, 5 mmol/l alternating with 25 mmol/l glucose, with or without Mn(III)tetrakis(4-benzoic acid) porphyrin chloride (MnTBAP) and thenoyltri-fluoroacetone (TTFA). The cell proliferation, VEGF expression, mitochondrial ROS, nitrotyrosine and 8-hydroxydeoxyguanosine (8-OHdG) were measured. In cultured HRECs, treatment with constant or intermittent high glucose significantly increased [(3)H]thymidine incorporation in a time-dependent manner. Treatment with constant high glucose for 48 h resulted in significant increases in [(3)H]thymidine incorporation, mRNA and protein levels of VEGF compared with HRECs treated with the normal glucose, which were markedly enhanced in cells exposed to intermittent high glucose. The levels of mitochondrial ROS, nitrotyrosine and 8-OhdG were significantly elevated under both intermittent and constant high glucose conditions, the effect being greater under intermittent high glucose. In addition, the antioxidants MnTBAP or TTFA can effectively prevent cell proliferation and overexpression of VEGF, as well as overproduction of mitochondrial ROS, nitrotyrosine and 8-OhdG in HRECs induced by constant or intermittent high glucose. Intermittent high glucose enhances cell proliferation and overexpression of VEGF through reactive oxygen species (ROS) overproduction at the mitochondrial transport chain level in HRECs, indicating that glycemic variability have important pathological effects on the development of diabetic retinopathy dependent of mitochondrial ROS.

[Diabetes-specific complications in prediabetes]

According to general belief, diabetes-specific late complications may occur only in overt diabetes mellitus. Nevertheless, several clinical observations recognized that diabetes-specific microangiopathic complications (diabetic retinopathy, nephropathy and neuropathy) might be observed even in subjects with prediabetes. The results of non-pharmacological investigations documented that not only the incidence of newly diagnosed type 2 diabetes but cardiovascular risk factors and microangiopathic late complications could also be decreased by life-style modification in subjects with prediabetes (impaired glucose tolerance).

Physical therapy in the 21st century (Part I): toward practice informed by epidemiology and the crisis of lifestyle conditions

Part I of this two-part introduction to this Special Issue on the practice of physical therapy in the 21st century outlines the epidemiological basis and rationale for evidence-informed physical therapy practice for addressing contemporary health priorities. This evidence emanates from the definition of health by the World Health Organization (WHO) and the International Classification of Functioning (ICF), and WHO and other international databases on the prevalence of lifestyle conditions. Lifestyle conditions include ischemic heart disease, smoking-related conditions, hypertension and stroke, obesity, diabetes, and cancer. Epidemiological data combined with evidence supporting the effectiveness of noninvasive interventions related to physical therapy to address these priorities (e.g., health education and exercise) are highly consistent with the promotion of health and wellness and the ICF. Given their commitment to exploiting effective noninvasive interventions, physical therapists are in a preeminent position to focus on prevention of these disabling and lethal conditions in every client or patient, their cure in some cases, as well as their management. Thus, a compelling argument can be made that clinical competencies in 21st century physical therapy need to include assessment of smoking and smoking cessation (or at least its initiation), basic nutritional assessment and counseling, recommendations for physical activity and exercise, stress assessment and basic stress reduction recommendations, and sleep assessment and basic sleep hygiene recommendations. The physical therapist can then make an informed clinical judgment regarding whether a client or patient needs to be referred to another professional related to one or more of these specialty areas. The prominence of physical therapy as an established health care profession and its unique pattern of practice (prolonged visits over prolonged periods of time) attest further to the fact that physical therapists are uniquely qualified to lead in the assault on lifestyle conditions. Evidence-based physical therapy practiced within the context of epidemiological indicators (i.e., evidence-informed practice) maximally empowers clinicians to promote lifelong health in every person and in turn, the health of communities. This vision of physical therapy's leading role in health promotion and health care in the 21st century holds the promise of reducing the need for invasive health interventions (drugs and surgery). Part II of this introduction describes evidence-based physical therapy practice within this context of evidence-informed practice.

Intermittent high glucose stimulate MCP-l, IL-18, and PAI-1, but inhibit adiponectin expression and secretion in adipocytes dependent of ROS

Elevated circulating concentrations of interleukin-18 (IL-18), monocyte chemoattractant protein-1 (MCP-1), and plasminogen activator inhibitor-1 (PAI-1) and decrease of adiponectin are associated with obesity-related diseases. The mechanism that mediates the aberrant production of the adipokines remains poorly understood. The aim of this study was to investigate the effect of intermittent high glucose on the expression of IL-18, MCP-1, and PAI-1 and adiponectin in 3T3-L1 adipocytes. 3T3-L1 adipocytes were incubated for 24 h in media containing different glucose concentrations: 5 mmol/l, 20 mmol/l and a daily alternating 5 or 20 mmol/l glucose, with or without the addition of1.0 mmol/l N-acetylcysteine (NAC). The expression and secretion of IL-18, MCP-1, PAI-1, and adiponectin were determined by real-time RT-PCR and ELISA, respectively.The production of reactive oxygen species (ROS) and 8-hydroxydeoxyguanosine(8-OHdG) were measured. Stable high glucose significantly increased expression and secretion of IL-18, MCP-1, and PAI-1, and reduced adiponectin expression and secretion compared to normal glucose conditions.These effects were significantly greater under intermittent high glucose conditions compared to stable high glucose. The level of ROS and 8-OHdG were significantly elevated under both intermittent and stable high glucose conditions, the effect being greater under intermittent high glucose. The intermittent glucose was more effective in triggering the generation of ROS than stable high glucose. The adding of the NAC, aspecific pharmacological inhibitor of ROS, normalized the expression of these adipokines and the levels of ROS and 8-OHdG under both stable and intermittent glucose conditions.Intermittent high glucose induces a greater aberrant production of key adipokines than stable high glucose, and this effect seems to be related to over-production of ROS.

Overproduction of phosphoprotein enriched in diabetes (PED) induces mesangial expansion and upregulates protein kinase C-beta activity and TGF-beta1 expression

AIMS/HYPOTHESIS

Overproduction of phosphoprotein enriched in diabetes (PED, also known as phosphoprotein enriched in astrocytes-15 [PEA-15]) is a common feature of type 2 diabetes and impairs insulin action in cultured cells and in mice. Nevertheless, the potential role of PED in diabetic complications is still unknown.

METHODS

We studied the effect of PED overproduction and depletion on kidney function in animal and cellular models.

RESULTS

Transgenic mice overexpressing PED (PEDTg) featured age-dependent increases of plasma creatinine levels and urinary volume, accompanied by expansion of the mesangial area, compared with wild-type littermates. Serum and kidney levels of TGF-beta1 were also higher in 6- and 9-month-old PEDTg. Overexpression of PED in human kidney 2 cells significantly increased TGF-beta1 levels, SMAD family members (SMAD)2/3 phosphorylation and fibronectin production. Opposite results were obtained following genetic silencing of PED in human kidney 2 cells by antisense oligonucleotides. Inhibition of phospholipase D and protein kinase C-beta by 2-butanol and LY373196 respectively reduced TGF-beta1, SMAD2/3 phosphorylation and fibronectin production. Moreover, inhibition of TGF-beta1 receptor activity and SMAD2/3 production by SB431542 and antisense oligonucleotides respectively reduced fibronectin secretion by about 50%. TGF-beta1 circulating levels were significantly reduced in Ped knockout mice and positively correlated with PED content in peripheral blood leucocytes of type 2 diabetic patients.

CONCLUSIONS/INTERPRETATION

These data indicate that PED regulates fibronectin production via phospholipase D/protein kinase C-beta and TGF-beta1/SMAD pathways in kidney cells. Raised PED levels may therefore contribute to the abnormal accumulation of extracellular matrix and renal dysfunction in diabetes.

Body mass index is associated with increased creatinine clearance by a mechanism independent of body fat distribution

CONTEXT

Although obesity has been, in general, associated with glomerular hyperfiltration, visceral adiposity has been suggested to be associated with reduced glomerular filtration.

OBJECTIVE

The aim of the study was to evaluate the differential effects of obesity and body fat distribution on glomerular filtration.

DESIGN AND SETTING

We conducted a cross-sectional study of the Japanese-American community in Seattle, Washington.

PARTICIPANTS

We studied a representative sample of second-generation Japanese-American men and women with normal glucose tolerance (n = 124) and impaired glucose metabolism (impaired fasting glucose and/or impaired glucose tolerance) (n = 144) residing in King County, Washington.

MAIN OUTCOME MEASURES

Glomerular filtration rate was estimated by 24-h urinary creatinine clearance, body size by body mass index (BMI), and intra-abdominal fat (IAF), sc fat (SCF), and lean thigh areas by CT scan.

RESULTS

Creatinine clearance was positively correlated with BMI (r = 0.429; P < 0.001), fasting glucose (r = 0.198; P = 0.001), and insulin levels (r = 0.125; P = 0.042), as well as IAF (r = 0.239; P < 0.001), SCF (r = 0.281; P < 0.001), and lean thigh (r = 0.353; P < 0.001) areas. The association between creatinine clearance and BMI remained significant after adjustments for IAF, SCF areas, and fasting insulin levels (r = 0.337; P < 0.001); whereas IAF and SCF areas were not independently associated with creatinine clearance after adjusting for BMI. Creatinine clearance increased with increasing BMI after adjusting for fasting insulin, fasting glucose, IAF and SCF areas in subjects with normal glucose tolerance (r = 0.432; P < 0.001) and impaired glucose metabolism (r = 0.471; P < 0.001).

CONCLUSIONS

BMI rather than body fat distribution is an independent determinant of creatinine clearance in nondiabetic subjects. Lean body mass, rather than adiposity, may explain this association.

Microvascular dysfunction in diabetic foot disease and ulceration

Diabetic foot disease and ulceration is a major complication that may lead to the amputation of the lower limbs. Microangiopathy may play a significant role in the pathogenesis of tissue breakdown in the diabetic foot. However, the precise mechanisms of this process remain unclear and poorly understood. Microvasculature in the skin is comprised of nutritive capillaries and thermoregulatory arteriovenous shunt flow. It is regulated through the complex interaction of neurogenic and neurovascular control. The interplay among endothelial dysfunction, impaired nerve axon reflex activities, and microvascular regulation in the diabetic patient results in the poor healing of wounds. Skin microvasculature undergoes both morphologic changes as well as functional deficits when parts of the body come under stress or injury. Two important theories that have been put forward to explain the abnormalities that have been observed are the haemodynamic hypothesis and capillary steal syndrome. With advances in medical technology, microvasculature can now be measured quantitatively. This article reviews the development of microvascular dysfunction in the diabetic foot and discusses how it may relate to the pathogenesis of diabetic foot problems and ulceration. Common methods for measuring skin microcirculation are also discussed.

A1C predicts type 2 diabetes and impaired glucose tolerance in a population at risk: the community diabetes prevention project

AIMS

In a population at risk for type 2 diabetes (T2DM), we assessed early physical and metabolic markers that predict progression from normal to impaired glucose tolerance (IGT) and T2DM.

METHODS

A total of 388 individuals (22% male, age 46 + 11 years) at risk for T2DM were randomized to Standard (n = 182) or Intervention (n = 206) care and evaluated at baseline and 5 annual follow-up visits, including blood pressure, BMI, A1C, lipids, urine albumin/creatinine ratio, VO2max, fasting glucose, insulin and C-peptide. The Standard group received results of annual lab tests and quarterly newsletters, while the Intervention group received quarterly newsletters and detailed discussions of lab results, routine self-directed activities, semi-annual group meetings and monthly telephone calls for ongoing support.

RESULTS

Overall, 359 (93%) returned for at least one follow-up visit and 272 (70%) completed the final 5-year assessment. Return rates, changes in measures and incidence of IGT/T2DM were similar between groups. Low cardiorespiratory fitness (VO2max) was the most prevalent baseline abnormality. A1C and BMI were significant predictors of IGT/T2DM after controlling for other factors. The risk of IGT/T2DM within 5 years was 17.16 (95% CL: 6.169, 47.736) times greater for those with baseline A1C>=5.8% as compared to those <5.8% (p < 0.0001).

CONCLUSION

Baseline A1C>=5.8% was a significant predictor of IGT/T2DM within 5 years in a population at high risk for T2DM. A1C is routinely performed among patients with diabetes, however these data and other evidence suggest that it may also be a useful tool for risk assessment and screening.

Reliability of quantitative sudomotor axon reflex testing and quantitative sensory testing in neuropathy of impaired glucose regulation

Reproducible neurophysiologic testing paradigms are critical for multicenter studies of neuropathy associated with impaired glucose regulation (IGR), yet the best methodologies and endpoints remain to be established. This study evaluates the reproducibility of neurophysiologic tests within a multicenter research setting. Twenty-three participants with neuropathy and IGR were recruited from two study sites. The reproducibility of quantitative sudomotor axon reflex test (QSART) and quantitative sensory test (QST) (using the CASE IV system) was determined in a subset of patients at two sessions, and it was calculated from intraclass correlation coefficients (ICCs). QST (cold detection threshold: ICC=0.80; vibration detection threshold: ICC=0.75) was more reproducible than QSART (ICC foot=0.52). The performance of multiple tests in one setting did not improve reproducibility of QST. QST reproducibility in our IGR patients was similar to reports of other studies. QSART reproducibility was significantly lower than QST. In this group of patients, the reproducibility of QSART was unacceptable for use as a secondary endpoint measure in clinical research trials.

[Pathophysiology and treatment for diabetic neuropathy]

Diabetic neuropathy (DN) is the most frequent among peripheral neuropathies. Since its pathophysiology is so complicated, neither classification nor therapeutic management of DN has been established. Sensory/autonomic polyneuropathy (DP) is the main type of DN. Since diabetic patients occasionally have one or more subtypes of DN and/or other polyneuropathy including treatable neuropathy like CIDP, the treatment for DP has to be conducted after excluding the possibility of other conditions. Glycemic control is most essential to prevent the development of DP. However, it is practically difficult to keep HbA1c under 6.5% so that drinking and smoking better be restricted and blood pressure be properly maintained to retard the progression of DP. Aldose reductase inhibitor is only one commercially available drug for DP and its efficacy must be evaluated by nerve function tests along with subjective symptoms. More vigorous therapeutic procedure is expected by obtaining not only more potential drugs based on pathogenic mechanisms but also the technique targeting of DNA/siRNA of given peptides at dorsal root ganglion neurons.

Biomarkers of body iron stores and risk of developing type 2 diabetes

AIM

Iron may contribute to the pathogenesis of type 2 diabetes mellitus (DM) by inducing oxidative stress and interfering with insulin secretion. Elevated ferritin levels are associated with increased DM risk among healthy individuals. However, it is yet unknown if ferritin predicts DM incidence among high-risk individuals with impaired glucose tolerance (IGT). Furthermore, the association between soluble transferrin receptors (sTfR), a novel marker of iron status, and DM risk has not yet been prospectively investigated in these individuals. We conducted this study to evaluate the association between baseline levels of ferritin and sTfR and the risk of developing DM among overweight and obese individuals at high risk of DM.

METHODS

This nested case-control study (280 cases and 280 matched controls) was conducted within the placebo arm of the Diabetes Prevention Program, is a clinical trial conducted among overweight/obese individuals with IGT. Ferritin and sTfR levels were measured by immunoturbidimetric assays. Incident DM was ascertained by annual 75-g oral glucose tolerance test and semi-annual fasting glucose.

RESULTS

Compared with controls, cases had higher sTfR levels (3.50 +/- 0.07 vs. 3.30 +/- 0.06 mg/l; p = 0.03), but ferritin levels were not statistically different. The multivariable odds ratios (OR) and 95% confidence intervals (95% CI) for DM incidence comparing highest with the lowest quartiles of sTfR was 2.26 (1.37-4.01) (p-trend: 0.008).

CONCLUSIONS

Modestly elevated sTfR levels are associated with increased DM risk among overweight and obese individuals with IGT. Future studies should evaluate factors determining sTfR levels and examine if interventions that lower body iron stores reduce DM incidence.

Glycaemic variability and inflammation in subjects with metabolic syndrome

Subjects who develop diabetes have an increased cardiovascular risk even before the appearance of diabetes. The aim of this study was to investigate the glycaemic variability measured by continuous glucose monitoring (CGM CV%) in nondiabetic subjects with metabolic syndrome (MS) and to explore if glycaemic variability was associated with circulating levels of interleukin-6 (IL-6), a proinflammatory cytokine, or with an anti-inflammatory factor like adiponectin. Three groups of obese subjects with (MS+: 6m, 8f; BMI 33.1+/-1.4 mean+/-SEM) or without metabolic syndrome (MS-: 2m, 4f; BMI 29.2+/-2.2) and with MS associated with type 2 diabetes (MS/T2D: 3m, 5f; BMI 32.9+/-1.4) were investigated. The glycaemic variability was measured in all subjects in terms of CV% of the glycaemic values obtained every 3 min during the course of a 48 h CGM performed using a subcutaneous glucose sensor. The average CGM CV% increased from MS- group (21.1%) to the MS+ group (23.9%) and to the MS+/T2D group (27.4%) but it was not correlated to the CGM mean glycaemia (r=0.20; P=ns). In some instances, CGM CV% was found higher in MS+ subjects than in some MS+ T2D ones. Stepwise multiple correlation analysis showed that IL-6 predicted CGM CV% (R(2)=0.35, beta=0.13; P<0.05) independently from BMI, waist circumference, adiponectin and insulin concentrations. In conclusion, the CGM CV% may contribute to better describe the individual metabolic state and to understand the pathogenesis of endothelial dysfunction in non diabetic subjects with MS.

Diabetic retinopathy is associated with insulin resistance and cardiovascular autonomic dysfunction in type 2 diabetic patients

Diabetic retinopathy (DR) and cardiovascular autonomic dysfunction are associated with high mortality in type 2 diabetic patients. This preliminary study was therefore designed to test the hypothesis that DR is associated with insulin resistance and cardiovascular autonomic dysfunction in type 2 diabetic patients without insulin treatment. Seventy persons were diagnosed to have type 2 diabetes in the examination from June 2004 to May 2006. The study group consisted of 29 type 2 diabetic patients with DR (age: 58+/-6 years, mean+/-s.d.) and 41 type 2 diabetic patients with no DR (NDR) (n=41, 58+/-5 years). Cardiovascular autonomic function was assessed by baroreflex sensitivity (BRS), heart rate variability, plasma norepinephrine concentration and cardiac (123)I-metaiodobenzylguanidine (MIBG) scintigraphic findings. DR patients had lower BRS, early and delayed (123)I-MIBG myocardial uptake values and higher percent washout rate (WR) of (123)I-MIBG than the NDR patients. With respect to metabolic findings, DR patients had higher fasting plasma insulin concentration (P<0.0001) and higher homeostasis model assessment (HOMA) index (P<0.00001) than the NDR patients. Multiple logistic regression analysis revealed that the presence of DR was independently predicted by HOMA index and the percent WR of (123)I-MIBG (P<0.01 and P<0.05, respectively). Our results suggest that DR is associated with depressed cardiovascular autonomic function and insulin resistance and that HOMA index and the percent WR of (123)I-MIBG are independently associated with DR in Japanese patients with type 2 diabetes mellitus.

Impaired glucose tolerance and endothelial damage, as assessed by levels of von Willebrand factor and circulating endothelial cells, following acute myocardial infarction

BACKGROUND

Impaired glucose tolerance (IGT) following acute myocardial infarction (AMI) increases the incidence of major adverse cardiac events. We hypothesized that endothelial damage following AMI, as assessed by levels of von Willebrand factor (vWF) and circulating endothelial cells (CECs), would be more pronounced in patients with IGT compared to those with normal glucose tolerance (NGT).

METHODS

We studied non-diabetic patients with AMI (n=125; 107 (86%) male; mean age 59 years (SD 12.5)) who underwent oral glucose tolerance testing 3-5 days after admission. We measured vWF (enzyme-linked immunosorbent assay) and CECs (CD146 immunobead capture) in the fasting state and at 2 h post glucose load.

RESULTS

Base-line vWF and CEC levels were higher in IGT patients versus those with NGT and healthy controls (HC) (P<0.001). The acute increase in vWF and CECs in response to the glucose load was significantly higher in the IGT group compared to those with NGT and HC (P<0.01)-an increase on a par with that seen in newly diagnosed diabetics.

CONCLUSION

The degree of endothelial damage post AMI in patients with IGT is greater than NGT, and comparable to that seen in frank diabetes mellitus. Subjects with IGT therefore need to be as actively sought and managed.

Skin microcirculatory dysfunction is already present in normoglycemic subjects with metabolic syndrome

The role of microcirculatory dysfunction (MD) in metabolic and cardiovascular diseases is not well established. Considering that metabolic syndrome (MS) is an independent risk factor and diabetic patients have microangiopathy, our aim was to investigate if normoglycemic subjects with MS already have detectable skin MD. Thirty-six subjects with MS (National Cholesterol Education Program-Adult Treatment Panel III criteria) (10 men/26 women, 38.8 +/- 7.9 years, 35.8 +/- 4.9 kg/m(2)) with normal glucose tolerance (American Diabetes Association criteria) and 16 controls (11 men/5 women, 33.6 +/- 8.4 years, 23.9 +/- 3.6 kg/m(2)) were studied using nailfold videocapillaroscopy. Afferent, efferent, and apical capillary diameters; functional capillary density; red blood cell velocity (RBCV) at baseline; and RBCV(max) and time (TRBCV(max)) to reach it during postocclusive reactive hyperemia after 1-minute arterial occlusion were measured. Subjects with MS had smaller afferent, efferent, and apical diameters (4.2 [3.8-4.2] vs 5.6 [4.65-6.25] mum, P < .001; 4.8 [4.2-4.8] vs 6.2 [5.6-7] mum, P < .001; and 5.2 [4.8-5.55] vs 7.4 [6.2-8] mum, P < .001); lower functional capillary density (7.28 [6.37-9.10] vs 10.4 [9.1-11.8] capillaries per square millimeter, P < .001), RBCV (0.62 [0.57-0.65] vs 0.79 [0.76-0.89] mm/s, P < .001], and RBCV(max) (1.14 [1.12-1.210] vs 1.57 [1.45-1.62] mm/s, P < .001); and longer TRBCV(max) (10.0 [10-11] vs 4.5 [4-6] seconds, P < .001) compared with controls. Microcirculatory dysfunction was associated with body mass index. We concluded that subjects with MS already have nutritive skin MD even within the normoglycemic milieu.

Arterial stiffness and cognition in elderly persons with impaired glucose tolerance and microalbuminuria

BACKGROUND

Cognitive decline that occurs frequently in impaired glucose tolerance (IGT) may be largely due to endothelial dysfunction. We assessed: (i) the relationships between impact of urinary albumin excretion rate (UAER), as marker of generalized endothelial dysfunction, and cognition; (ii) if cognitive decline could be explained by arterial stiffening using pulse wave velocity (PWV).

METHODS

One hundred forty older patients (age range 70-85 years) with IGT and no dementia were selected. Patients were classified according to 24-hour UAER: normoalbuminuric (NA) (UAER<20 microg/min) or microalbuminuric (MA) (UAER between 20 and 199 microg/min). Cognitive abilities were assessed by the Mini-Mental State Examination (MMSE) and a composite score of executive and attention functioning (CCS) at baseline and after 12 months of follow-up.

RESULTS

In MA patients (n=80), increased UAERs correlated with intimal media thickness (IMT) (r=0.268; p=02) and PWV (r=0.310; p=004). In the same group, increased UAERs were correlated with MMSE and CCS even after adjusting for age and mean arterial blood pressure (MABP). After adding PWV, the associations among UAERs, MMSE, and CCS were no longer significant. In MA patients, PWV correlated with IMT, MMSE, and CCS. In NA patients, no significant correlations were found among UAERs, MMSE, and CCS. At follow-up, baseline UAERs predicted an approximately 20% risk of poor cognition (according to MMSE and CCS) after adjusting for confounders. After adding PWV, UAERs no longer predicted cognitive performance.

CONCLUSIONS

MA older persons with IGT showed a decline in cognition performance that may be partially explained by arterial stiffness.

Evaluation of peripheral and autonomic neuropathy among patients with newly diagnosed impaired glucose tolerance

BACKGROUND

We have aimed to investigate the presence of peripheral and autonomic neuropathy in individuals who had been diagnosed with impaired glucose tolerance (IGT) on the basis of an oral glucose tolerance test, by comparing with age-matched healthy subjects with an oral glucose tolerance test (OGTT) in normoglycemic ranges.

MATERIAL AND METHODS

Conventional nerve conduction studies, heart rate variation variability, heart rate response to deep breathing, heart rate response to valsalva maneuvre, blood pressure response to standing up quickly, hand grip test and sympathetic skin response tests were used to evaluate the IGT and the control subjects.

RESULTS

No obvious statistical difference indicating peripheral neuropathy and/or cardiac autonomic neuropathy was detected between patient group and controls. Amplitudes of sympathetic skin response of two limbs (right upper and lower extremities) were lower in the IGT patient group when compared to healthy controls (p < 0.05) indicating the presence of sudomotor autonomic neuropathy.

CONCLUSION

Complaints and neurological examinations of patients with IGT were thought to be consistent with small-fiber neuropathy in the early phase of glucose intolerance. Not detecting any neuropathic findings in conventional electroneurography should be attributed to insufficient time allowed for settling down of large-fiber neuropathy. Obtaining no response in some of the patients in addition to general decrease in the amplitudes of sympathetic skin responses indicates that sudomotor fibers tend to be affected earlier in autonomic neuropathy in the group with IGT when compared with healthy controls. Newly diagnosed IGT patients take receive priority in primary protection since the time for settling down of cardiac autonomic neuropathy was short.

Diabetic neuropathy: mechanisms to management

Neuropathy is the most common and debilitating complication of diabetes and results in pain, decreased motility, and amputation. Diabetic neuropathy encompasses a variety of forms whose impact ranges from discomfort to death. Hyperglycemia induces oxidative stress in diabetic neurons and results in activation of multiple biochemical pathways. These activated pathways are a major source of damage and are potential therapeutic targets in diabetic neuropathy. Though therapies are available to alleviate the symptoms of diabetic neuropathy, few options are available to eliminate the root causes. The immense physical, psychological, and economic cost of diabetic neuropathy underscore the need for causally targeted therapies. This review covers the pathology, epidemiology, biochemical pathways, and prevention of diabetic neuropathy, as well as discusses current symptomatic and causal therapies and novel approaches to identify therapeutic targets.

[Microcirculation in diabetes: implications for chronic complications and treatment of the disease]

Diabetic microangiopathy is responsible for an important rate of morbidity and mortality related to the disease. Endothelial damage seems to be the triggering factor in the pathogenesis of microvascular complications. Diabetes mellitus and other metabolic diseases are associated to endothelial dysfunction, the most precocious known marker of atherosclerosis. Changes on microvascular reactivity are present in patients with diabetes mellitus, as well as in individuals with risk factors for this disease. Evaluation of endothelial and microvascular functions is possible using different invasive or preferentially non-invasive methods. Adequate control of diabetes mellitus might postpone or perhaps even prevent the microvascular disease. Microvascular dysfunction, when seen only by changes on microvascular reactivity, could be ameliorated with correction of risk factors or drug treatment.

Idiopathic neuropathy patients are at high risk for metabolic syndrome

BACKGROUND

Idiopathic neuropathy patients are at high risk of impaired glucose tolerance (IGT). Hyperglycemia, low high density lipoprotein (HDL), elevated triglycerides (TRG), hypertension and central obesity co-associate and constitute the metabolic syndrome. Patients with hyperglycemia are at high risk of having the syndrome and each of its features. Our null hypothesis was that patients with neuropathy and IGT would have a higher prevalence of other metabolic syndrome features than those without hyperglycemia. The primary objective was to determine if metabolic syndrome features other than hyperglycemia increase neuropathy risk.

METHODS

The prevalence of metabolic syndrome features was determined among 219 sequential patients with idiopathic peripheral neuropathy. Subjects were classified as having IGT or normoglycemia. The prevalence of metabolic syndrome was compared to published population prevalence data. To compensate for potential referral bias, data were also compared for175 diabetic subjects without neuropathy, given the well-recognized risk of metabolic syndrome among diabetic individuals.

RESULTS

Contrary to our hypothesis, neuropathy patients with normoglycemia and IGT shared a similarly elevated prevalence of metabolic syndrome features compared to published normal populations. Compared to diabetic subjects without neuropathy, the normoglycemic neuropathy patients had significantly higher total and LDL cholesterol, and a higher prevalence of abnormal HDL and triglycerides. The prevalence of obesity and hypertension was similar among patient groups. Normoglycemic neuropathy subjects had significantly more features of metabolic syndrome (other than hyperglycemia) than diabetics.

CONCLUSIONS

These findings demonstrate an association between neuropathy and metabolic syndrome features other than hyperglycemia. Lipid abnormalities are particularly prevalent among neuropathy subjects.

Insulin-like growth factor-binding protein-1 in the prediction and development of type 2 diabetes in middle-aged Swedish men

AIMS/HYPOTHESIS

Insulin-like growth factor-binding protein-1 (IGFBP-1) production in the liver is inhibited by insulin, and low circulating levels are associated with the metabolic syndrome. The aim of this study was to evaluate the predictive role and change in IGFBP-1 concentrations during development of abnormal glucose regulation.

METHODS

IGFBP-1 levels were determined at baseline and at 10 years in an incident case-control prospective study of Swedish white men aged 35-56 years. Individuals with normal glucose tolerance at baseline who developed abnormal glucose tolerance during a 10 year period (n = 355) according to WHO criteria were pair-matched to controls for age and family history of diabetes.

RESULTS

Fasting IGFBP-1 concentrations were lower in individuals who later developed abnormal glucose regulation and correlated inversely with fasting proinsulin values (r = -0.48; p < 0.0001), and both were significant predictors. Individuals in the highest quartile at baseline for an algorithm incorporating fasting IGFBP-1, blood glucose, proinsulin and waist and height had a 40-fold increased risk of developing type 2 diabetes compared with the lowest quartile (95% CI 7.7-214). IGFBP-1 increased 32% (95% CI 17-49%) during the 10 years in those developing diabetes and was increased in relation to insulin levels, suggesting the emergence of hepatic insulin resistance. Moreover, elevated IGFBP-1 levels at follow-up were associated with higher 2 h glucose values during an OGTT.

CONCLUSIONS/INTERPRETATION

Low IGFBP-1 predicts the development of abnormal glucose regulation and, as an inhibitor of the insulin-like actions of insulin-like growth factors, elevated levels of IGFBP-1 after the development of diabetes may also play a pathophysiological role.

Aryl hydrocarbon receptor is activated by glucose and regulates the thrombospondin-1 gene promoter in endothelial cells

Hyperglycemia is an independent risk factor for development of diabetic vascular complications. The molecular mechanisms that are activated by glucose in vascular cells and could explain the development of vascular complications are still poorly understood. A putative binding site for the transcription factor aryl hydrocarbon receptor (AhR) was identified in the glucose-responsive fragment of the promoter of thrombospondin-1, a potent antiangiogenic and proatherogenic protein involved in development of diabetic vascular complications. AhR was expressed in aortic endothelial cells (ECs), activated, and bound to the promoter in response to high glucose stimulation of ECs. The constitutively active form of AhR induced activation of the thrombospondin-1 gene promoter. In response to high glucose stimulation, AhR was found in complex with Egr-1 and activator protein-2, which are 2 other nuclear transcription factors activated by glucose in ECs that have not been previously detected in complex with AhR. The activity of the DNA-binding complex was regulated by glucose through the activation of hexosamine pathway and intracellular glycosylation. This is the first report of activation of AhR (a receptor for xenobiotic compounds) by a physiological stimulus. This report links the activation of AhR to the pathological effects of hyperglycemia in the vasculature.

Standing balance and trunk position sense in impaired glucose tolerance (IGT)-related peripheral neuropathy

Type 2 diabetes mellitus (T2DM) and pre-diabetes or impaired glucose tolerance (IGT) affect a large segment of the population. Peripheral neuropathy (PN) is a common complication of T2DM, leading to sensory and motor deficits. While T2DM-related PN often results in balance- and mobility-related dysfunction which manifests as gait instability and falls, little is known about balance capabilities in patients who have evidence of PN related to IGT (IGT-PN). We evaluated patients with IGT-PN on commonly-used clinical balance and mobility tests as well as a new test of trunk position sense and balance impairment, trunk repositioning errors (TREs). Eight participants aged 50-72 years with IGT-PN, and eight age- and gender-matched controls underwent balance, mobility and trunk repositioning accuracy tests at a university neurology clinic and mobility research laboratory. Compared to controls, IGT-PN participants had as much as twice the magnitude of TREs and stood approximately half as long on the single leg balance test. People with IGT-PN exhibit deficits in standing balance and trunk position sense. Furthermore, there was a significant association between performance on commonly-used clinical balance and mobility tests, and electrophysiological and clinical measures of neuropathy in IGT-PN participants. Because IGT-related neuropathy represents the earliest stage of diabetic neuropathy, deficits in IGT-PN participants highlight the importance of early screening in the dysglycemic process for neuropathy and associated balance deficits.

Impaired glucose tolerance and neuropathy

BACKGROUND

Peripheral neuropathy is common. Diabetes is the most common cause, accounting for approximately half of cases, but up to 1/3rd of neuropathy patients have no identifiable etiology. Among this population, impaired glucose tolerance (IGT or "prediabetes") is observed in approximately 40%. The exact nature of the relationship between IGT and neuropathy is debated.

REVIEW SUMMARY

A variety of evidence suggests IGT causes neuropathy. Neuropathy may occur early in diabetes. The neuropathy associated with IGT is clinically similar to early diabetic neuropathy, with preferential injury to small nerve fibers resulting in pain and autonomic dysfunction. IGT and diabetic neuropathy patients share abnormal microvascular endothelial dysfunction. Treatment of IGT subjects with diet and exercise reduces risk of progression to diabetes, and those with neuropathy experience a short-term improvement in small fiber function with sustained benefit for pain. An evolving literature links other aspects of the metabolic syndrome to peripheral neuropathy.

CONCLUSIONS

IGT is common in peripheral neuropathy patients. The extent to which IGT directly causes nerve injury as opposed to being a covariant with other equally or more important features (eg, obesity, metabolic syndrome) remains to be determined. Preliminary data suggest diet and exercise counseling may be a useful treatment strategy.

Alanine variant of the Pro12Ala polymorphism of the PPARgamma gene might be associated with decreased risk of diabetic retinopathy in type 2 diabetes

OBJECTIVE

Molecular background of diabetic retinopathy (DR) remains unknown. An interesting group of candidate genes encode proteins involved in insulin resistance.

AIM

To search for association between the PPARgamma, calpain 10, PTPN1 genes and DR in type 2 diabetes mellitus (T2DM).

METHODS

We examined 238 T2DM subjects without DR (NDR) and 121 with DR (mean diabetes duration: 9.1+/-6.8 and 15.1+/-7.7, respectively). The subjects were genotyped for four markers: Pro12Ala of PPARgamma, SNP43 of calpain 10, rs3787345 and rs754118 of PTPN1. The distributions of the genotypes were compared using the chi(2)-test and Fisher exact test.

RESULTS

The alleles and genotypes were not associated with DR in non-stratified analysis. To investigate the impact of T2DM duration, we performed analysis that excluded short duration NDR subjects and long-duration DR subjects. It allowed obtaining groups with similar T2DM duration but different DR status (DR: 88 individuals, 11.4+/-5.3 years; NDR: 136 individuals, 13.2 years+/-6.2, respectively). This analysis suggested that the alanine variant of Pro12Ala might be associated with decreased risk of DR (p=0.026 for alleles, p=0.038 and p=0.014 for genotypes in additive and dominant models, respectively). In multivariable logistic regression that included non-genetic parameters, Pro12Ala was not an independent risk factor (p=0.28). Further analysis showed, however, that Pro12Ala remained significant when urea level was excluded from the model.

CONCLUSION

The alanine variant of the Pro12Ala polymorphism of PPARgamma might be associated with decreased risk of DR in T2DM. This effect may be indirect, at least in part, due to diabetic kidney disease.

Oxidative injury and neuropathy in diabetes and impaired glucose tolerance

Clinical studies suggest that impaired glucose tolerance (IGT) is associated with the development of neuropathy. The aim of the current study was to determine if neuropathy developed in the female Zucker Diabetic Fatty (ZDF) rat, an animal model of IGT and type 2 diabetes. The ZDF rat develops impaired glucose tolerance (IGT) when fed a control diet, and frank diabetes when fed a high fat diet. Following 10 weeks of hyperglycemia, sensory nerve action potentials (SNAP) and compound motor action potentials (CMAP) were reduced and sensory conduction velocities were slowed (distal>proximal) in the tail and hind limb in ZDF animals with IGT and frank diabetes (p<0.01). Neuropathy was coupled with evidence of increased reactive oxygen species (ROS) and cellular injury in dorsal root ganglion (DRG) neurons from IGT animals. Our study supports the hypothesis that neuropathy develops in an animal model of IGT and is associated with evidence of oxidative injury in DRG and peripheral nerves.

Glucose metabolism, insulin resistance, and renal pathology in non-diabetic chronic kidney disease

BACKGROUND

The relation between insulin resistance and atherosclerosis is widely recognized, but it remains unknown whether glucose metabolism/insulin resistance is related to renal pathology in humans.

METHODS

We quantitatively evaluated pathological changes in the glomeruli, tubulointerstitium, and vessels in renal biopsy specimens from 23 patients with non-diabetic chronic kidney disease (CKD), all of whom took a 75-gram oral glucose tolerance test. We correlated the renal pathological changes with fasting plasma glucose (FPG), fasting plasma insulin, 2-hour plasma glucose (2-h PG), 2-hour plasma insulin (2-h PI), homeostasis model assessment of insulin resistance (HOMA-IR), and body mass index.

RESULTS

HOMA-IR exceeded 1.73 in 11 patients (47.8%), and 2-h PI exceeded 64.0 microU/ml in 14 (60.9%). FPG significantly correlated with interstitial fibrosis (r = 0.532, p = 0.009). The significance was marginal in the correlation between FPG and tubular atrophy and arterio-arteriolosclerosis. Statistically significant correlation was also found between 2-h PG and arterio-arteriolosclerosis (r = 0.422, p = 0.04) and between HOMA-IR and interstitial fibrosis (r = 0.416, p = 0.04).

CONCLUSION

Although precise mechanisms remain unknown, glucose metabolism/insulin resistance seem to play pathogenic roles in formation and progression of renal pathological changes, especially tubulointerstitial and vascular lesions, in non-diabetic CKD.

Cardiovascular disease and type 2 diabetes mellitus: a multifaceted symbiosis

Chronic hyperglycaemia (e.g. type 2 diabetes mellitus (T2DM) and prediabetes) in humans is associated with an increased risk of cardiovascular (CV) complications, and, vice versa, the presence of CV complications (e.g. myocardial infarction, stroke or intermittent claudication) among patients heightens the risk of T2DM or prediabetes. In both cases (i.e. chronic hyperglycaemia and CV complications), significant diagnostic and treatment challenges resulting from a broad range of factors may serve as barriers to reducing the deleterious societal impact of T2DM and prediabetes. These challenges often include clinicians: failing to intervene early and aggressively enough among patients with T2DM to achieve CV risk factor control; failing to efficaciously identify T2DM patients with already established CV complications; and failing proactively to assess individuals at high risk for T2DM. This review discusses the apparent symbiosis between CV disease and T2DM, with a focus on identifying patients with established T2DM or at risk for T2DM; traditional and novel risk factors and markers for CV disease in T2DM; challenges related to diagnosing CV disease in T2DM; and organization of T2DM care in order to prevent CV complications. These are issues that require attention because identifying patients at high risk for T2DM can halt or reduce their further glycaemic deterioration if addressed properly, and because novel markers and non-invasive tests could be applied in patients with T2DM as a means of detecting and possibly treating unrecognized CV disease in time. Furthermore, several approaches for T2DM care can be effective in controlling the CV risk factors contributing to CV complications.

Endothelin-A receptor blockade increases nutritive skin capillary circulation in patients with type 2 diabetes and microangiopathy

AIMS

Endothelin-1 levels are elevated in patients with type 2 diabetes mellitus and may contribute to impaired microvascular function. We investigated the effect of selective endothelin-A (ET(A)) receptor blockade (BQ123) on skin microcirculation in patients with type 2 diabetes and albuminuria.

METHODS

Ten type 2 diabetes patients and 8 non-diabetic controls were investigated. Nutritive skin capillary circulation, investigated by videophotometric capillaroscopy, and total skin microcirculation, assessed by laser Doppler flux-metry (LDF), were studied during intra-arterial infusion of saline for 15 min, followed by BQ123 infusion for 60 min.

RESULTS

Following BQ123 infusion there was a significant increase in resting capillary blood cell velocity (CBV) in patients with type 2 diabetes from 0.24 (0.20-0.34) mm/s at baseline to 0.61 (0.46-0.88) mm/s at 60 min, but no significant change in the control subjects [0.55 (0.10-0.68) vs. 0.38 (0.13-0.88) mm/s; p < 0.005 for difference between groups]. Peak CBV following arterial occlusion and skin temperature increased significantly in the type 2 diabetes group but not in the control group during BQ123 infusion. There were no significant changes in LDF parameters during infusion of BQ123 in either group.

CONCLUSION

ET(A) receptor blockade improves nutritive skin capillary circulation in patients with type 2 diabetes and microangiopathy.

Blood glucose and cerebrovascular disease in nondiabetic patients

The objective of this study was to determine if elevations in blood glucose, in a range classified as impaired fasting glucose, are associated with a greater incidence of cerebrovascular disease in nondiabetic patients. Morning blood glucose determinations were evaluated with respect to subsequent stroke using records from 28 477 nondiabetic patients. Strokes and transient ischemic attacks (TIA) were identified from ICD-9 coding for a new event more than a year after baseline glucose determinations. Of the patients studied, 593 suffered stroke or TIA over a total risk analysis time of 100 982 years. Higher baseline morning glucose (100 to 126 mg/dL vs under 100 mg/dL) was associated with 31% more diagnoses (2.4% vs 1.8%, P < .001). Incidence rate was 5.3 per 1000 patient-years for those patients with glucose over 100 mg/dL and 3.9 per 1000 patient-years for those with glucose under 100 mg/dL (P <.001). Kaplan-Meier analysis showed that elevated baseline glucose was associated with a progressive, increased risk with time. A Cox proportional hazards model with adjustment for age, body mass index, sex, creatinine, lipids, smoking, and medications showed that elevated fasting glucose was associated with an increased hazard for a new event (hazard ratio 1.24, 95% CI 1.05-1.46, glucose over 100 mg/dL vs under 100 mg/dL). Thus, patients with higher baseline blood glucose levels in the absence of diabetes and after adjustment for covariants have a significantly greater risk for development of cerebrovascular disease.

Does impaired glucose metabolism cause polyneuropathy? Review of previous studies and design of a prospective controlled population-based study

In spite of extensive studies it is unclear whether impaired fasting glucose (IFG) or impaired glucose tolerance (IGT), i.e., impaired glucose metabolism (IGM), causes diabetic sensorimotor polyneuropathy (DSPN) or chronic idiopathic axonal polyneuropathy (CIAP); the results and conclusions vary considerably in different studies. Some studies suggest that IGM is a common and important cause of CIAP, whereas others do not. On reviewing these data, we judge that a considerable degree of this disparity may relate to differences in selection of patients, choice of controls, assessment of chronic glycemic exposure and of diabetic complications, and statistical power. Here we review previous studies, list the reasons that the issue needs further study, and outline a study now in progress to address the question more definitively.