Non-diabetic Volunteers Research Articles

Effects of acute insulin-induced hypoglycaemia on psychomotor function: people with type 1 diabetes are less affected than non-diabetic adults

We examined the effects of acute insulin-induced hypoglycaemia on psychomotor function in non-diabetic volunteers and in adults with type 1 diabetes. Non-diabetic adults (n = 20) and adults with type 1 diabetes mellitus (n = 16) each underwent a euglycaemic-hyperinsulinaemic glucose clamp on two separate occasions. Arterialised blood glucose was maintained for 1 h at either 4.5 mmol/l (euglycaemia) or 2.5 mmol/l (hypoglycaemia). During this time participants underwent neuropsychological tests to assess psychomotor function. During hypoglycaemia the non-diabetic participants showed a significant deterioration in the following: (1) four-choice reaction time (p = 0.008); (2) grooved pegboard (a test of manual dexterity; p = 0.004); (3) hand steadiness (p = 0.003); (4) pursuit rotor (a test of fine motor function, attention and coordination; p = 0.018); and (5) test of total body coordination (p = 0.004). No significant differences were observed between euglycaemia and hypoglycaemia in hand-grip (p = 0.897) and line tracing time (p = 0.480) tests. In type 1 diabetes mellitus patients, only four-choice reaction time (p = 0.023) and pursuit rotor (p = 0.045) were impaired significantly during hypoglycaemia. Although acute hypoglycaemia caused significant impairment of several psychomotor functions in non-diabetic adults, a lower magnitude of impairment was observed in those with type 1 diabetes. The mechanism underlying this discrepant effect of hypoglycaemia on psychomotor function remains unknown, but may be related to the difference in sympathoadrenal activation observed between the groups. People with type 1 diabetes may also have had a behavioural advantage of over non-diabetic participants derived from their previous exposure to hypoglycaemia or potentially the disparate results arose from hypoglycaemia-induced cerebral adaptation.

The glycemic index of bread and biscuits is markedly reduced by the addition of a proprietary fiber mixture to the ingredients

Background and aim Low glycemic index (GI) foods are associated with improved prevention and control of metabolic and cardiovascular diseases (e.g. diabetes and myocardial infarction), even if the impact of their consumption within mixed meals is difficult to predict. Since the availability of wheat based products maintaining taste and texture of traditional ones, but with a low GI, is of relevant nutritional interest, the aim of this study was to assess the effects of a specific proprietary fiber mix, added to the wheat flour used for biscuits and bread preparation, on their GI. Methods and results Fifteen healthy non-diabetic volunteers ate on different days a portion equivalent to 75 g of available carbohydrates, of fiber enriched bread, traditional bread, fiber enriched biscuits and traditional biscuits, or a solution of 75 g of glucose in water. The glycemic index of each product was calculated by relating the area under their glycemic curve to that of glucose. The areas under the glycemic curves of fiber enriched bread and biscuits were lower than those obtained with the equivalent control food. Consequently, a marked reduction of their GI of 21% and 41% for bread and biscuits, respectively, was observed. Conclusion The fiber mix added to the flour used in the preparation of biscuits and bread markedly reduces their GI. A similar effect could be expected in other oven-baked foods produced using the same fiber supplementation.

Evaluation of the VIA® Blood Chemistry Monitor for Glucose in Healthy and Diabetic Volunteers

Manual methods of blood glucose monitoring are labor-intensive, costly, prone to error, and expose the caregiver to blood. The VIA(R) blood chemistry monitor for glucose can automatically measure plasma glucose (PG) every 5 minutes for 72 hours using blood sampled from a peripheral vein/artery or a central vein. VIA performance was evaluated in eight normal and five type 1 diabetic (T1DM) subjects in 15 separate experiments. The VIA device was connected to a peripheral vein and reported a PG value every 5 minutes during each 510-minute experiment. Blood samples were collected manually every 10 minutes and assayed using a HemoCue(R) beta-glucose analyzer (HC). Whole blood HC measurements were corrected to PG values. Paired HC/VIA measurements (n = 717) were analyzed. Mean PG was 90 +/- 14 and 96 +/- 12 mg/dl in normal subjects and 194 +/- 64 and 173 +/- 48 mg/dl in T1DM subject as measured by the HC and VIA, respectively. Clark error grid analysis revealed 86% points in zone A, 11% points in zone B, and 2% points in zone D. Linear regression analysis yielded the following equation: VIA = 0.732 x HC + 30.5 (r(2) = 0.954). Residual analysis revealed a glucose-dependent bias between the HC and the VIA. VIA data were transformed using the linear regression equation to correct for bias. After the correction, the mean absolute relative difference between the VIA and the HC was less than 10%, and 99.6% of data were in zones A and B. The VIA was able to sample blood automatically every 5 minutes for more than 8 hours in the laboratory setting. On average, the VIA reported glucose values for 94% of the samples it attempted to obtain. This study demonstrated that the VIA blood chemistry monitor for glucose can reliably sample blood frequently for a prolonged period of time safely and effectively in diabetic and nondiabetic volunteers. Agreement between the two devices was the closest at normal glucose concentrations. After correcting for a glucose-dependent bias between the devices, the MARD was consistently less than 10% for all glucose ranges.

Acute hyperglycaemia induces an inflammatory response in young patients with type 1 diabetes

Background. Patients with type 1 diabetes (T1D) are at a substantially increased risk of cardiovascular disease. Stress-induced hyperglycaemia in turn is shown to worsen the prognosis of patients suffering from an acute myocardial infarction. However, the mechanisms behind these findings are incompletely known.Aim. To investigate whether markers of chronic inflammation, and oxidative stress respond to acute hyperglycaemia in patients with T1D.Methods. The plasma glucose concentration was rapidly raised from 5 to 15 mmol/L in 35 males (22 men with T1D and 13 age-matched non-diabetic volunteers) and maintained for 2 h. All participants were young non-smokers without any signs of diabetic or other complications. Markers of chronic inflammation, and oxidative stress were analysed in serum/plasma samples drawn at base-line and after 120 min of hyperglycaemia.Results. Compared to normoglycaemia, acute hyperglycaemia increased the interleukin (IL)-6 concentrations by 39% in patients with T1D (P<0.01) and 26% in healthy volunteers (P<0.05). During hyperglycaemia the superoxide dismutase concentration was increased by 17% in the healthy volunteers (P<0.01) and 5% in the patients with type 1 diabetes (P=NS). The increase in tumour necrosis factor (TNF)-α was larger in patients with type 1 diabetes than in non-diabetic volunteers (35% versus −10%, P<0.05).Conclusions. This study shows that acute hyperglycaemia induces an inflammatory response in patients with type 1 diabetes.

Acute hyperglycaemia disturbs cardiac repolarization in Type 1 diabetes

Patients with Type 1 diabetes have an increased risk of cardiovascular mortality. Notably, a prolonged heart rate adjusted QT interval (QTc) is a predictor of sudden cardiovascular death. Therefore, the objectives of this study were to investigate whether acute hyperglycaemia affects the QTc duration and the QTc dispersion in patients with Type 1 diabetes and in healthy volunteers. Acute hyperglycaemia (15 mmol/l) for 120 min was induced in 35 males (22 men with Type 1 diabetes and 13 age-matched non-diabetic volunteers). All participants were non-smokers without any diabetic complications. Electrocardiogram recordings were performed at normoglycaemia and at 0, 60 and 120 min of hyperglycaemia. Compared with normoglycaemia, acute hyperglycaemia increased the QTc interval in both patients with Type 1 diabetes (390 +/- 6 vs. 415 +/- 5 ms, P < 0.001) and in healthy volunteers (378 +/- 5 vs. 412 +/- 8 ms, P < 0.01). During hyperglycaemia, the QTc dispersion was prolonged in healthy volunteers (36 +/- 4 ms vs. 54 +/- 7 ms, P < 0.05) but not in patients with Type 1 diabetes (45 +/- 3 ms at baseline vs. 48 +/- 5 ms, NS). Acute hyperglycaemia alters myocardial ventricular repolarization in patients with Type 1 diabetes and in healthy volunteers and might consequently be an additional risk factor for cardiovascular events.

Mass Spectral Determination of Fasting Tear Glucose Concentrations in Nondiabetic Volunteers

There is considerable disagreement regarding the concentration of glucose in tears and its relationship to the concentration in blood. Improved sampling and analysis methods may resolve these discrepancies and possibly provide a basis for in situ tear glucose sensors. We used liquid chromatography (LC) with electrospray ionization mass spectrometry (ESI-MS) to determine glucose in 1-muL tear fluid samples obtained from 25 fasting study participants. Tear fluid was collected with microcapillaries and a slitlamp microscope. The median (range) of fasting tear glucose concentrations was 28 (7-161) micromol/L or 0.50 (0.13-2.90) mg/dL. The SD of tear glucose measurements for individuals varied linearly with the mean tear glucose concentration and was approximately half of the mean. We found no significant difference in tear glucose concentrations between contact lens users and nonusers (P = 0.715). We observed significant correlations between fasting blood and tear glucose concentrations (R = 0.50, P = 0.01). Our tear fluid collection and analysis method enables reliable measurement of equilibrium, fasting tear glucose concentrations. These concentrations are lower than those previously reported for nondiabetic persons. Larger population studies are required to determine correlations between blood and tear glucose concentrations and to determine the utility of contact lens-based sensors for the monitoring of diabetes. Our methods are applicable for study of other tear fluid analytes and may prove useful for monitoring other disease states.

Fluorescent serum and urinary advanced glycoxidation end-products in non- diabetic subjects

Advanced glycoxidation end-products (AGEs) are involved in age-related conditions and diabetic complications. Diet intake contributes to their circulating concentrations. To measure serum and urinary AGEs in non-diabetic volunteers and relate their concentration to body composition, blood chemistry and dietary ingestion. We studied 41 adult men (31 middle-aged adults and 10 elderly). A nutritional assessment including a dietary recall designed for detection of AGE ingestion (specifically carboxymethyl-lysine(CML)), and anthropometric measurements were performed. Also serum lipoproteins, insulin, glucose, leptin and C reactive protein (CRP). AGEs were measured in serum and urine samples using size exclusion chromatography and flow injection assay (FIA); the technical procedures were first employed in 11 heterogeneous diabetics, as positive controls for this methodology. Serum and urinary chromatograms indicated that areas under the curve were not different in younger compared with elderly adults. AGEs did not correlate with dietary intake, body composition, nor metabolic parameters, however they correlated significantly with renal function and CRP concentration. In these non-diabetic volunteers, with low CML intake, serum and urinary concentration of AGEs were not related to dietary intake. AGEs were related to renal function and CRP, but not to body composition, lipoproteins, insulin and glucose.

Waist circumference does not predict circulating adiponectin levels in sub-Saharan women

BackgroundBecause of previously reported ethnic differences in determinants and markers of obesity and related metabolic disorders, we sought to investigate circulating levels of adiponectin and their correlates in a sub-Saharan African (sSA) population.Subjects and MethodsWe studied 70 non-diabetic volunteers (33M/37F) living in Yaoundé, Cameroon, aged 24–69 yr, with BMI 20–42 kg/m2. In all participants we measured waist circumference and total body fat by bioimpedance, and obtained a fasting venous blood sample for measurement of plasma glucose, serum insulin and adiponectin concentrations. We performed a euglycaemic hyperinsulinaemic clamp in 1/4 subjects, and HOMAIR was used as surrogate of fasting insulin sensitivity index since it best correlates to clamp measurements.ResultsMales had lower adiponectin levels than females (8.8 ± 4.3 vs. 11.8 ± 5.5 μg/L). There was no significant correlation between adiponectin and total body fat (rs = -0.03; NS), whereas adiponectin was inversely correlated with waist circumference (rs = -0.39; p = 0.001). Adiponectin correlated negatively with insulin resistance (rs = -0.35; p = 0.01). In a regression analysis using fasting adiponectin concentration as the dependent variable, and age, HOMAIR, waist circumference, and fat mass as predictors, waist circumference (β = -3.30; p = 0.002), fat mass (β = -2.68; p = 0.01), and insulin resistance (β = -2.38; p = 0.02) but not age (β = 1.11; p = 0.27) were independent predictors of adiponectin. When considering gender, these relations persisted with the exception of waist circumference in females.ConclusionAdiponectin correlates in this study population are comparable to those observed in Caucasians with the exception of waist circumference in women. The metabolic significance of waist circumference is therefore questioned in sSA women.

Prediction of Postprandial Glycemic Exposure

To determine the best predictors of total postprandial glycemic exposure and peak glucose concentrations in nondiabetic humans. Data from 203 nondiabetic volunteers who ingested a carbohydrate-containing mixed meal were analyzed. Fasting glucose and insulin concentrations were poor predictors of postprandial glucose area above basal (R2 = approximately 0.07, P < 0.001). The correlation was stronger for 2-h glucose concentration (R2 = 0.55, P < 0.001) and improved slightly but significantly (P < 0.001) with the addition of fasting glucose, insulin, age, sex, and body weight to the model (r2 = 0.58). The 2-h glucose concentration also predicted the peak glucose concentration (R2 = 0.37, P < 0.001) with strength of the prediction increasing (P < 0.001) modestly with the addition of fasting glucose, insulin, age, sex, and body weight to the model (R2 = 0.48, P < 0.001). On the other hand, addition of measures of body function and composition did not improve prediction of total glycemic exposure or peak glucose concentration. Isolated measures of fasting or 2-h glucose concentrations alone or in combination with more complex measures of body composition and function are poor predictors of postprandial glycemic exposure or peak glucose concentration. This may explain, at least in part, the weak and at times inconsistent relationship between these parameters and cardiovascular risk.

A refractometry-based glucose analysis of body fluids

In principle, refractometry appears to be a suitable method for the measurement of glucose concentrations in body fluids (such as blood and the intercellular fluid), even though the refractive index of the measured samples, as an additive property, is not specific. But, if certain conditions are fulfilled, the glucose content can be calculated using the refractive index in combination with values from a further measurement. This study describes the determination of the glucose content using refractometry in human blood serum derivates, which were selected – due to their ready availability – to be used as a model for interstitial fluid. Refractometry of body fluids requires the elimination of disturbing components from the measurement sample. First of all, a homogenous fluid (i.e. consisting of one phase) is required, so that all cells and components in suspension need to be separated out. Furthermore, certain dissolved macromolecular components which are known to disturb the measurement process must also be removed. In human serum samples which had been ultrafiltrated with a range of ultrafilters of different pore sizes, a comparative evaluation showed that only ultrafiltration through a filter with a separation limit of between 3 and 30 kDa resulted in maximal reduction of the refractive index (compared to native serum), whereas ultrafilters with greater separation limits did not. The total content of osmotically active solutes (the tonicity) also exerts a clear influence. However, exemplary measurements in blood plasma fluid from one volunteer showed that the electrical conductivity is (without an additive component) directly proportional to the osmolality: physiological changes in the state of body hydration (hyperhydration and dehydration) do not lead to any considerable changes in the relation between ionised and uncharged solute particles, but instead result in a sufficiently clear dilution or concentration of the blood fluid's low molecular components. This finding allows the use of the – technically easy to measure – electrical conductivity as a measure for the tonicity of the measurement samples. Using measurements of these two parameters – refractive index and electrical conductivity – in blood serum obtained from a healthy volunteer, a two-dimensional calibration function (calibration matrix) for the assessment of the glucose content of ultrafiltrated human blood serum was constructed, and the measurement of blood glucose levels in non-diabetic (four females and four males) volunteers in comparison to a reference method was evaluated showing (as a proof of concept) a linear association. Assessment of the inaccuracy of these measurements made with the described measuring devices and methods showed a deviation from the reference values of less than 10%. An estimation of the maximum possible error showed relative deviations (maximum measurement uncertainties) of up to 20%.

Insulin Resistance Causes Human Gallbladder Dysmotility

Obesity, diabetes, and hyperlipidemia are known risk factors for the development of gallstones. A growing body of animal and human data has correlated insulin resistance with organ dysfunction. The relationship among obesity, diabetes, hyperlipidemia, and abnormal gallbladder motility remains unclear. Therefore, we designed a study to investigate the association among obesity, insulin resistance, hyperlipidemia, and gallbladder dysmotility. One hundred ninety-two healthy adult nondiabetic volunteers were studied. Gallbladder ultrasounds were performed before and after a standardized fatty meal. A gallbladder ejection fraction (EF) was calculated, and an EF of < 25% was considered abnormal. Serum was analyzed for cholesterol, triglycerides, cholecystokinin, leptin, glucose, and insulin. The homeostasis assessment model (HOMA) was used to determine insulin resistance. The volunteers had a mean age of 38 years (range, 18-77), and 55% were female. Thirty subjects (15%) had gallstones and were excluded from the study. Thirty subjects (19%) had abnormal gallbladder motility (EF < 25%). In lean subjects (n = 96) fasting glucose was significantly increased in the 16 subjects with gallbladder EF < 25% versus the 80 subjects with gallbladder EF > 25% (109 +/- 20 mg/dl versus 78 +/- 2 mg/dl, P < 0.05). Similarly, the HOMA index was significantly greater in subjects with gallbladder EF < 25% versus gallbladder EF >25% (3.3 +/- 1.2 versus 2.0 +/- 0.2, P < 0.05). In obese subjects (n = 66), fasting glucose, insulin, and insulin resistance were not associated with a gallbladder EF < 25%. These data suggest that in lean, nondiabetic volunteers without gallstones, gallbladder dysmotility is associated with an elevated fasting glucose as well as a high index of insulin resistance. We conclude that insulin resistance alone may be responsible for gallbladder dysmotility that may result in acalculous cholecystitis or gallstone formation.

The effect of aspirin and vitamins C and E on HbA 1c assays

Background Aspirin (ASA) and vitamins C and E may inhibit non-enzymatic glycation in vivo and may also interfere with HbA 1c assays, masking true results. We investigated the effect of usual doses of ASA, vitamin C and E on HbA1c levels in a group of non-diabetic volunteers. Methods A randomized clinical trial was performed with 28 healthy non-diabetic individuals. Subjects were allocated to take ASA 200 mg/day, vitamin C 1 g/day, vitamin E 400 mg/day, or to a control group, for a period of 4 months. Blood samples were collected at baseline and at monthly intervals for HbA1c analysis by HPLC Variant II (BioRad), HPLC L-9100 (Merck – Hitachi) and Tina Quant® HbA 1c II immunoassay (Roche). Results HbA 1c levels of the control, vitamin C and E groups did not change throughout the study, independently of the method used. HbA 1c measured by Hitachi L-9100 HPLC increased significantly ( P = 0.033) at 4 months after ASA intake, although this increase was of only 0.17%. Conclusions: Treatment with vitamins C and E in pharmacological doses does not have any impact on HbA1c measurements in non-diabetic patients with the three methods employed. ASA induces a modest, not clinically relevant, increase in HbA1c levels with one of the methods.

The Role of Endocrine Counterregulation for Estimating Insulin Sensitivity from Intravenous Glucose Tolerance Tests

During insulin-modified frequently sampled iv glucose tolerance tests (IM-FSIGT), which allow assessment of insulin action, plasma glucose can markedly decrease. This study aimed to assess the counterregulatory impact of the insulin-induced fall of glucose on minimal model-derived indices of insulin sensitivity (S(I)) and glucose effectiveness. Thirteen nondiabetic volunteers (seven males, six females, aged 26 +/- 1 yr, body mass index 22.1 +/- 0.7 kg/m(2)) were studied. All participants were studied in random order during IM-FSIGT (0.3 g/kg glucose; 0.03 U/kg insulin at 20 min) and during identical conditions but with a variable glucose infusion preventing a decrease of plasma glucose concentration below euglycemia (IM-FSIGT-CLAMP). Five participants additionally underwent euglycemic-hyperinsulinemic (1 mU.kg(-1).min(-1)) clamp tests. Plasma glucose declined during IM-FSIGT to its nadir of 50 +/- 3 mg/dl at 60 min in parallel to a rise (P < 0.05 vs. basal) of plasma glucagon, cortisol, epinephrine, and GH. Glucose infusion rates of 4.6 +/- 0.5 mg.kg(-1).min(-1) between 30 and 180 min during IM-FSIGT-CLAMP prevented the decline of plasma glucose and the hypoglycemia counterregulatory hormone response. S(I) was approximately 68% lower during IM-FSIGT (3.40 +/- 0.36 vs. IM-FSIGT-CLAMP: 10.71 +/- 1.06 10(-4).min(-1) per microU/ml, P < 0.0001), whereas glucose effectiveness did not differ between both protocols (0.024 +/- 0.002 vs. 0.021 +/- 0.003 min(-1), P = NS). Compared with the euglycemic hyperinsulinemic clamp test, S(I) expressed in identical units from IM-FSIGT was approximately 66% (P < 0.001) lower but did not differ between the euglycemic hyperinsulinemic clamp test and the IM-FSIGT-CLAMP (P = NS). The transient fall of plasma glucose during IM-FSIGT results in lower estimates of S(I), which can be explained by hormonal response to hypoglycemia.

Serum 25-Hydroxyvitamin D3 Concentrations and Prevalence of Cardiovascular Disease Among Type 2 Diabetic Patients

Accumulating research suggests that low 25-hydroxyvitamin D3 [25(OH)D] concentrations may be inversely associated with type 2 diabetes (1,2,3), metabolic syndrome (4,5), insulin resistance (6), and cardiovascular disease (CVD) (7). Much remains to be learned, however, about the relationships between vitamin D status, metabolic syndrome, and CVD. Furthermore, the published data in humans arguing that hypovitaminosis D is a CVD risk factor remain conflicting (8,9). Because this topic has received scant attention and the available information on associations between vitamin D status and CVD among type 2 diabetic adults was lacking, we examined the relationships between serum 25(OH)D concentrations and prevalent CVD in type 2 diabetic adults. We studied 459 consecutive type 2 diabetic outpatients attending our clinic after exclusion of those with recent acute illness or advanced chronic liver or renal disease and those who were taking medications known to alter vitamin D metabolism. The control group consisted of 459 (64% men, age 61 ± 6 years) age- and sex-matched nondiabetic volunteers. Biochemical blood measurements were determined by standard laboratory procedures. Serum 25(OH)D concentrations were measured during winter months using an automated chemiluminescence immunoassay (DiaSorin Liaison). Metabolic syndrome was defined according to the Adult Treatment Panel III criteria (10). Presence of coronary (myocardial infarction, angina, or …

Pravastatin does not affect insulin sensitivity and adipocytokines levels in healthy nondiabetic patients

Background The effect of statins on insulin resistance is controversial and poorly studied in nondiabetic subjects. In addition, the effect of statins on leptin and adiponectin has never been studied. Methods Forty healthy nondiabetic volunteers (22 men and 18 women) aged 28 to 72 were randomized either to placebo or pravastatin 40 mg daily for a 12-week period. Insulin resistance, assessed using the Quantitative Insulin Sensitivity Check Index (QUICKI), as well as serum leptin and adiponectin levels, was measured at baseline and at the end of therapy. Results Pravastatin treatment decreased total cholesterol, low-density lipoprotein cholesterol, and triglycerides levels by 24%, 32%, and 14%, respectively ( P < .05 for all), but did not affect glucose and insulin levels, the (QUICKI) index, and adiponectin and leptin levels. When stratification was performed according to QUICKI index or sex, no significant differences were observed in the prevalues and postvalues of leptin, adiponectin, or QUICKI index in the pravastatin group. Adiponectin, leptin, and QUICKI index were statistically higher in women than in men ( P < .001 for both variables). Adiponectin was negatively correlated with body mass index (BMI; r = −0.39, P < .05) and positively correlated with the QUICKI index ( r = 0.54, P < .001) and with high-density lipoprotein cholesterol ( r = 0.50, P < .01). The relation between adiponectin and QUICKI index remained significant after adjustment for sex and BMI ( P = .005 and P = .007, respectively). Leptin was only related to BMI ( r = 0.57, P < .001) and to sex ( P < .001) with no significant correlations with lipid parameters or QUICKI index. Both sex and BMI are independent predictors of leptin ( P < .001 and P < .001). Conclusion A 12-week treatment with pravastatin 40 mg/d does not change the QUICKI index and leptin and adiponectin levels in healthy volunteers. In addition, our results emphasize the importance of sex and BMI in the determination of both adiponectin and leptin. Adiponectin was also related to QUICKI index, whereas this relation was not found with leptin.

The Ingestion of Ginkgo biloba Extract (EGb 761) Inhibits Arachidonic Acid-Mediated Platelet Aggregation and Thromboxane B2 Production in Healthy Volunteers

Twelve non-diabetic volunteers (age = 39 +/- 13 years, BMI = 23.5 +/- 3.5) undertook a randomized double-blind placebo-controlled crossover study in which they ingested either 120 mg of EGb 761 or a placebo daily for 3 months and then switched to the other test capsules for the next 3 months. Platelet aggregation in platelet-rich plasma (PRP) was performed at the end of each 3-month arm, with or without 1-min incubation with graded doses of EGb 761. In the placebo cycles, AA-stimulated TXB2 production was 2581 +/-1337 pg/10(6) platelets (range 897-5485) compared to 1668 +/- 992 pg/10(6) platelets (range 6-1668) in the EGb 761 cycles (p < 0.005). Incubation of PRP with EGb 761 (150 microg/ml) completely inhibited platelet aggregation accompanied by inhibition of TXB2 synthesis in all subjects both in the placebo (<200 pg TXB2/10(6) platelets) and EGb 761 cycles (< 120 TXB2/10(6) platelets) (p < 0.0001). These results support EGb 761-mediated inhibition of platelet TXB2 synthesis in vivo.

Individual and Combined Effects of Peroxisome Proliferator‐Activated Receptor α and γ Agonists, Fenofibrate and Rosiglitazone, on Biomarkers of Lipid and Glucose Metabolism in Healthy Nondiabetic Volunteers

This open-label, randomized, placebo-controlled, incomplete-block, 3-period crossover pilot study investigated the effects of peroxisome proliferator-activated receptor alpha- and gamma-agonists on biomarkers of lipid and glucose metabolism in 12 nondiabetic subjects. Plasma samples were collected before and after each 14-day treatment with placebo, fenofibrate (201 mg/d), rosiglitazone (4 mg twice daily), and combined fenofibrate (201 mg/d) plus rosiglitazone (4 mg twice daily). Except for triglycerides (P < .042) and free fatty acids (P < .074), no significant interaction was demonstrated between fenofibrate and rosiglitazone; thus, the effect due to each drug alone was evaluated (presence/absence of drug). Fenofibrate significantly (P < .050) increased lipoprotein lipase activity (35%) and decreased apolipoproteins B (13%) and C-III (20%). Rosiglitazone significantly (P < .050) decreased fasting glucose (7.3%) and increased apolipoprotein C-III (19%) and adiponectin (137%). Fenofibrate and rosiglitazone also produced effects on triglycerides and free fatty acids, but it was not possible to determine if these effects were synergistic in nature.

The expression of Metalloproteinases (MMP) mRNA in an ex-vivo model of keratinocytes is not different between diabetic patients and non-diabetic controls

Understanding the molecular basis of the diabetic foot syndrome represents an important step towards a rational treatment. Normal healing depends on a balance in the wound between MMP's and tissue inhibitors of MMP's (TIMP's). We have previously demonstrated significant differences of MMP expression and proliferation in fibroblasts In the present study, we investigated the mRNA levels of MMP's in keratinocytes in an ex-vivo culture model. Methods: In this study 15 diabetic patients and eleven non-diabetic controls were included. From each patient a 5mm punch biopsy of the right thigh was taken. Keratinocytes were separated and cultivated. Collected keratinocytes were studied by RT-PCR (TaqMan) for MMP-1, -2–9; TIMP-1 and TIMP-2. Results: We found no statistical relevant differences for MMP's or TIMP's mRNA between cultivated keratinocytes of diabetic and non-diabetic volunteers. However, there was a tendency towards a higher mRNA expression in keratinocytes of patients with diabetes mellitus. Discussion: In diabetic patients impairment of wound healing begins on cellular level, thus reflecting the systemic character of the primary disease. In contrast to the data of an increased mRNA expression of MMP's and decreased levels of mRNA of TIMP's in cultures of diabetic fibroblasts, this effect was not found in a ex-vivo model of keratinocytes.

Increased renal glucose metabolism in Type 1 diabetes mellitus

In poorly controlled diabetes, increased renal glucose uptake has been implicated in the pathogenesis of diabetic nephropathy by promoting nonenzymatic glycosylation of proteins, activation of protein kinase C, and increased polyol pathway flux. However, whether glucose uptake by the diabetic kidney is actually increased, especially in patients with Type 1 diabetes, is unclear. To examine this question, we used a combination of net balance and isotopic techniques to compare renal glucose uptake in 12 subjects with Type 1 diabetes before and after restoration of near normoglycaemia by infusion of insulin with that in 15 postabsorptive nondiabetic volunteers. Prior to insulin infusion, the diabetic subjects were markedly hyperglycaemic (arterial glucose 15.8 +/- 0.9 vs. 4.4 +/- 0.1 mm) and their renal tissue glucose uptake (i.e. total glucose disappearance across the kidney minus glycosuria) was increased more than 2 1/2-fold (388 +/- 43 vs. 148 +/- 12 micromol/min, P < 0.001). This was wholly explained by the mass action effects of hyperglycaemia since the diabetic subjects had normal renal blood flow (1575 +/- 82 vs. 1492 +/- 68 mL/min, P = 0.46) and reduced renal tissue glucose fractional extraction (1.7 +/- 0.2 vs. 2.3 +/- 0.1%, P = 0.027). Insulin infusion for three hours, which restored near normoglycaemia (arterial glucose 7.6 +/- 0.7 mm), reduced renal tissue glucose uptake toward normal (258 +/- 41 micromol/min, P = 0.006) without altering renal blood flow (1557 +/- 110, P = 0.63) or renal tissue glucose fractional extraction (2.1 +/- 0.3%, P = 0.35). Renal and hepatic glucose release, which had been increased (419 +/- 49 and 960 +/- 54 vs. 204 +/- 9 and 734 +/- 32 micromol/min, both P < 0.001), were suppressed by insulin to 138 +/- 22 and 520 +/- 53 micromol/min, respectively (both P < 0.001). In poorly controlled Type 1 diabetes, renal glucose uptake is markedly increased, which provides a link between hyperglycaemia and biochemical processes implicated in the pathogenesis of diabetic nephropathy. Its reversal by restoration of near normoglycaemia with insulin may explain the benefit of intensive insulin therapy in preventing diabetic nephropathy.

Cooling the Foot to Prevent Diabetic Foot Wounds

The etiology of neuropathic diabetic foot wounds can be summarized by the following formula: pressure x cycles of repetitive stress = ulceration. The final pathway to ulceration consists of an inflammatory response, leading to tissue breakdown. Mitigation of this response might reduce the risk of ulceration. This proof-of-concept trial evaluates whether simple cooling of the foot can safely reduce the time to thermal equilibrium after activity. After a 15-min brisk walk, the six nondiabetic volunteers enrolled were randomly assigned to receive either air cooling or a 10-min 55 degrees F cool water bath followed by air cooling. The process was then repeated with the intervention reversed, allowing subjects to serve as their own controls. There was a rise in mean +/- SD skin temperature after 15 min of activity versus preactivity levels (87.8 degrees +/- 3.9 degrees versus 79 degrees +/- 2.2 degrees F; P = .0001). Water cooling immediately brought the foot to a point cooler than preactivity levels for all subjects, whereas air cooling required an average of nearly 17 min to do so. Ten minutes of cooling required a mean +/- SD of 26.2 +/- 5.9 min to warm to preactivity levels. No adverse effects resulted from the intervention. We conclude that cooling the foot may be a safe and effective method of reducing inflammation and may serve as a prophylactic or interventional tool to reduce skin breakdown risk.