Effects of intermittent fasting on periodontal inflammation and subgingival microbiota

BACKGROUND

Studies on the impact of intermittent fasting on periodontal health are still scarce. Thus, this study evaluated the effects of long-term intermittent fasting on periodontal health and the subgingival microbiota.

METHODS

This pilot study was part of a nonrandomized controlled trial. Overweight/obese participants (n = 14) entered an intermittent fasting program, specifically the 5:2 diet, in which they restricted caloric intake to about a quarter of the normal total daily caloric expenditure for two nonconsecutive days/week. Subjects underwent a thorough clinical and laboratory examination, including an assessment of their periodontal condition, at baseline and 6 months after starting the diet. Additionally, subgingival microbiota was assessed by 16S rRNA gene sequencing.

RESULTS

After 6 months of intermittent fasting, weight, body mass index, C-reactive protein, hemoglobin A1c (HbA1c), and the cholesterol profile improved significantly (p < 0.05). Moreover, significant reductions were observed in bleeding on probing (p = 0.01) and the presence of shallow periodontal pockets after fasting (p < 0.001), while no significant change was seen in plaque index (p = 0.14). While we did not observe significant changes in α- or β-diversity of the subgingival microbiota related to dietary intervention (p > 0.05), significant differences were seen in the abundances of several taxa among individuals exhibiting ≥60% reduction (good responders) in probing pocket depth of 4-5 mm compared to those with <60% reduction (bad responders).

CONCLUSION

Intermittent fasting decreased systemic and periodontal inflammation. Although the subgingival microbiota was unaltered by this intervention, apparent taxonomic variability was observed between good and bad responders.

Smart Pen Exposes Missed Basal Insulin Injections and Reveals the Impact on Glycemic Control in Adults With Type 1 Diabetes

BACKGROUND

Adherence to basal insulin injections and the effects of missed basal insulin injections in adults with type 1 diabetes (T1D) were investigated using data from continuous glucose monitoring (CGM) and smart insulin pen devices in a real-world study.

METHODS

This was a post hoc analysis of a prospective, real-world study conducted in Sweden. Adults with T1D who were using CGM received a smart insulin pen device (NovoPen 6) for insulin injections. Missed basal insulin doses (≥40 hours between doses) were evaluated over 14-day periods, and the probability of missing basal insulin doses was estimated. Associations between missed basal insulin doses and glycemic outcomes were also explored.

RESULTS

Thirty-two patients with 4410 acceptable CGM days (315 14-day periods) were included. The number of missed basal insulin doses ranged from 0 to 4 over 315 14-day periods. The estimated probability of missing at least one basal insulin dose over any given 14-day period was 22% (95% confidence interval: 10%-40%). Missed basal insulin doses were significantly associated with higher mean glycemic levels, higher glucose management indicator, and lower time in range (70-180 mg/dL [3.9-10.0 mmol/L]). Similar results were observed when adjusted for missed bolus insulin doses; age and sex had no statistically significant effect on any glycemic parameter.

CONCLUSIONS

This is the first study, based on accurate real-world injection data, to demonstrate the challenge of adherence to basal insulin injections in patients with T1D, and document that just one missed basal injection per week can result in clinically significant changes in glycemic control.

Effect of Isocaloric Meals on Postprandial Glycemic and Metabolic Markers in Type 1 Diabetes-A Randomized Crossover Trial

The aim of this study was to assess the effect of four isocaloric meals with different macronutrient compositions on postprandial blood glucose, lipids, and glucagon in adults with type 1 diabetes (T1D). Seventeen subjects tested four isocaloric meals in a randomized crossover design. The meal compositions were as follows: high-carbohydrate (HC); high-carbohydrate with extra fiber (HC-fiber); low-carbohydrate high-protein (HP); and low-carbohydrate high-fat (HF). Blood glucose and lipid measurements were collected up to 4 h and glucagon up to 3 h postprandially. Mean postprandial glucose excursions were lower after the HP compared to the HC (p = 0.036) and HC-fiber meals (p = 0.002). There were no differences in mean glucose excursions after the HF meal compared to the HC and HP meals. The HF meal resulted in higher triglyceride excursions compared to the HP meal (p < 0.001) but not compared to the HC or HC-fiber meals. Glucagon excursions were higher at 180 min after the HP meal compared to the HC and HF meals. In conclusion, the low-carbohydrate HP meal showed the most favorable glycemic and metabolic effects during a 4 h postprandial period in subjects with T1D.

The impact of macronutrient composition on metabolic regulation: An Islet-Centric view

AIM

The influence of dietary carbohydrates and fats on weight gain is inconclusively understood. We studied the acute impact of these nutrients on the overall metabolic state utilizing the insulin:glucagon ratio (IGR).

METHODS

Following in vitro glucose and palmitate treatment, insulin and glucagon secretion from islets isolated from C57Bl/6J mice was measured. Our human in vivo study included 21 normoglycaemia (mean age 51.9 ± 16.5 years, BMI 23.9 ± 3.5 kg/m² , and HbA1c 36.9 ± 3.3 mmol/mol) and 20 type 2 diabetes (T2D) diagnosed individuals (duration 12 ± 7 years, mean age 63.6 ± 4.5 years, BMI 29.1 ± 2.4 kg/m² , and HbA1c 52.3 ± 9.5 mmol/mol). Individuals consumed a carbohydrate-rich or fat-rich meal (600 kcal) in a cross-over design. Plasma insulin and glucagon levels were measured at -30, -5, and 0 min, and every 30 min until 240 min after meal ingestion.

RESULTS

The IGR measured from mouse islets was determined solely by glucose levels. The palmitate-stimulated hormone secretion was largely glucose independent in the analysed mouse islets. The acute meal tolerance test demonstrated that insulin and glucagon secretion is dependent on glycaemic status and meal composition, whereas the IGR was dependent upon meal composition. The relative reduction in IGR elicited by the fat-rich meal was more pronounced in obese individuals. This effect was blunted in T2D individuals with elevated HbA1c levels.

CONCLUSION

The metabolic state in normoglycaemic individuals and T2D-diagnosed individuals is regulated by glucose. We demonstrate that consumption of a low carbohydrate diet, eliciting a catabolic state, may be beneficial for weight loss, particularly in obese individuals.

Real-world use of once-weekly semaglutide in patients with type 2 diabetes: pooled analysis of data from four SURE studies by baseline characteristic subgroups

INTRODUCTION

This post hoc pooled analysis of four real-world studies (SURE Canada, Denmark/Sweden, Switzerland and UK) aimed to characterize the use of once-weekly (OW) semaglutide, a glucagon-like peptide-1 receptor agonist (GLP-1RA), in patients with type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

The Semaglutide Real-world Evidence (SURE) studies had a duration of ~30 weeks. Changes in glycated hemoglobin (HbA_1c) and body weight (BW) were analyzed for the overall population and the following baseline subgroups: GLP-1RA-naïve/GLP-1RA switchers; body mass index <25/≥25-<30/≥30-<35/≥35 kg/m²; age <65/≥65 years; HbA_1c <7%/≥7-≤8%/>8-≤9%/>9%; T2D duration <5/≥5-<10/≥10 years. Data for patients achieving treatment targets were analyzed in the overall population and the baseline HbA_1c ≥7% subgroup.

RESULTS

Of 1212 patients, 960 were GLP-1RA-naïve and 252 had switched to semaglutide from another GLP-1RA. In the overall population, HbA_1c was reduced from baseline to end of study (EOS) by -1.1% point and BW by -4.7 kg; changes were significant for all subgroups. There were significantly larger reductions of HbA_1c and BW in GLP-1RA-naïve versus GLP-1RA switchers and larger reductions in HbA_1c for patients with higher versus lower baseline HbA_1c. At EOS, 52.6% of patients in the overall population achieved HbA_1c <7%. No new safety concerns were identified in any of the completed SURE studies.

CONCLUSIONS

In this pooled analysis, patients with T2D initiating OW semaglutide showed significant improvements from baseline to EOS in HbA_1c and BW across various baseline subgroups, including patients previously treated with a GLP-1RA other than semaglutide, supporting OW semaglutide use in clinical practice.

TRAIL REGISTRATION NUMBERS

NCT03457012; NCT03631186; NCT03648281; NCT03876015.

Repression of hypoxia-inducible factor-1 contributes to increased mitochondrial reactive oxygen species production in diabetes

Background:

Excessive production of mitochondrial reactive oxygen species (ROS) is a central mechanism for the development of diabetes complications. Recently, hypoxia has been identified to play an additional pathogenic role in diabetes. In this study, we hypothesized that ROS overproduction was secondary to the impaired responses to hypoxia due to the inhibition of hypoxia-inducible factor-1 (HIF-1) by hyperglycemia.

Methods:

The ROS levels were analyzed in the blood of healthy subjects and individuals with type 1 diabetes after exposure to hypoxia. The relation between HIF-1, glucose levels, ROS production and its functional consequences were analyzed in renal mIMCD-3 cells and in kidneys of mouse models of diabetes.

Results:

Exposure to hypoxia increased circulating ROS in subjects with diabetes, but not in subjects without diabetes. High glucose concentrations repressed HIF-1 both in hypoxic cells and in kidneys of animals with diabetes, through a HIF prolyl-hydroxylase (PHD)-dependent mechanism. The impaired HIF-1 signaling contributed to excess production of mitochondrial ROS through increased mitochondrial respiration that was mediated by Pyruvate dehydrogenase kinase 1 (PDK1). The restoration of HIF-1 function attenuated ROS overproduction despite persistent hyperglycemia, and conferred protection against apoptosis and renal injury in diabetes.

Conclusions:

We conclude that the repression of HIF-1 plays a central role in mitochondrial ROS overproduction in diabetes and is a potential therapeutic target for diabetic complications. These findings are timely since the first PHD inhibitor that can activate HIF-1 has been newly approved for clinical use.

Funding:

This work was supported by grants from the Swedish Research Council, Stockholm County Research Council, Stockholm Regional Research Foundation, Bert von Kantzows Foundation, Swedish Society of Medicine, Kung Gustaf V:s och Drottning Victorias Frimurarestifelse, Karolinska Institute’s Research Foundations, Strategic Research Programme in Diabetes, and Erling-Persson Family Foundation for S-B.C.; grants from the Swedish Research Council and Swedish Heart and Lung Foundation for T.A.S.; and ERC consolidator grant for M.M.

Real-world use of once-weekly semaglutide in patients with type 2 diabetes: Results from the SURE Denmark/Sweden multicentre, prospective, observational study

AIMS

As part of the SURE programme, SURE Denmark/Sweden aimed to study the real-world use of once-weekly (OW) semaglutide in adults with type 2 diabetes (T2D) in Denmark/Sweden.

METHODS

SURE Denmark/Sweden was an ∼30-week, prospective, multicentre, open-label, observational study, enrolling adults with T2D and ≥1 documented HbA_1c value ≤12 weeks before initiating semaglutide at their physician's discretion. Primary (change in HbA_1c) and secondary (including change in body weight, glycaemic and weight-loss target achievement) endpoints were assessed between baseline and end of study (EOS).

RESULTS

Of the 331 patients initiating semaglutide, 282 (85%) completed the study on treatment. For the latter, estimated mean changes [95% confidence interval] in HbA_1c and body weight between baseline and EOS were -1.2 [-1.3; -1.1]%-points (-13 [-14; -12] mmol/mol) and -5.4 [-6.0; -4.7] kg (both p < 0.0001), respectively, with similar results in Denmark and Sweden. At EOS, 67.5% of patients achieved HbA_1c <7%; 49.4% achieved a weight reduction of ≥5%. Reported adverse events were consistent with the known safety profile of semaglutide.

CONCLUSIONS

In routine clinical practice in Denmark/Sweden, use of OW semaglutide was associated with glycaemic and weight-loss benefits in a wide range of adults with T2D, supporting real-world use. CLINICALTRIALS.

GOV IDENTIFIER

NCT03648281.

Corrigendum to "Protective Effect of the HIF-1A Pro582Ser Polymorphism on Severe Diabetic Retinopathy"

[This corrects the article DOI: 10.1155/2019/2936962.].

Predictors of normalized HbA1c after gastric bypass surgery in subjects with abnormal glucose levels, a 2-year follow-up study

Clinical biomarkers can predict normalization of HbA1c after Roux-en-Y gastric bypass (RYGB) surgery, but it is unclear which are the most predictive.The aim of this study was to compare biomarkers for insulin sensitivity and other clinical parameters in the prediction of normalization of HbA1c after RYGB surgery. This study included 99 (23 men) obese subjects (BMI > 35 kg/m²) undergoing a laparoscopic RYGB. Clinical and biochemical examinations were performed pre-operatively and up to 2 years after surgery. Pre-operatively, normal fasting glucose levels were found in 25 individuals (NG), prediabetes in 46 and type 2 diabetes (T2DM) in 28. At baseline IGF-I (SD), IGFBP-1 and adiponectin levels were low while leptin was high. Weight loss was observed in all three groups, most in the prediabetes group. After 2 years HbA1c was decreased in prediabetes and T2DM. In all three groups insulin, HOMA-IR, lipids and blood pressure improved, IGFBP-1 and adiponectin increased and leptin decreased. IGF-I (SD) increased only in T2DM. In those with prediabetes or T2DM (n = 74), HbA1c at 2 years correlated to baseline BMI (r = -0.27, p = 0.028), age (r = 0.43, p < 0.001), HbA1c (r = 0.37, p = 0.001) and IGFBP-1 (r = 0.25, p = 0.038), and was normalized in 45/74 (61%) at 1 year and in 36 subjects (49%) at 2 years. These responders were younger, had higher BMI, larger waist circumference, lower HbA1c and lower IGFBP-1 levels at baseline. In a multiple regression model age (negative, p = 0.021) and waist circumference (positive, p = 0.047) were the only predictors for normalized HbA1c. RYGB normalized HbA1c in 49% at two years follow-up, which was predicted by low baseline IGFBP-1 level, a marker of hepatic insulin sensitivty and insulin secretion. However,. younger age and larger waist circumference were the only predictors of normalized HbA1c in multivariate analysis.

Human apolipoprotein CIII levels; evaluation of three assay methods

Apolipoprotein CIII (apoCIII) is associated with triglyceride (TG)-rich particles like VLDL and exerts an inhibitory effect of lipoprotein lipase. Increased levels are related to cardiovascular diseases and diabetes and therefore apoCIII has been proposed as a useful biomarker. Even if several commercial assays for measuring apoCIII in human plasma/serum are available, data is scarce concerning their reliability and none is used clinically. In the present study a comparative investigation has been done. Two ELISA-based methods (Cusabio Biotech and Assay Pro) and one nephelometric assay (Siemens Healthcare) were investigated. Serum and plasma samples were obtained from healthy volunteers and from samples sent to the Laboratory of Clinical Chemistry, preferably with higher levels of TGs. The Cusabio Biotech assay did not yield any valid results. However, both the methods from Assay Pro and Siemens Healthcare showed good performance with similar dynamic ranges. The latter assay had lower CV and required less work. In healthy individuals, apoCIII levels were not affected by fasting, freezing or thawing, nor did we find any gender differences. Individuals with elevated levels of TG displayed higher apoCIII values. Females with oral intake of contraceptives had higher levels. In conclusion, the nephelometric assay showed the best performance with the lowest CV, was less labor intensive than an assay based on ELISA and could therefore be suitable for clinical use.

Protective Effect of the HIF-1A Pro582Ser Polymorphism on Severe Diabetic Retinopathy

OBJECTIVE

Hypoxia is central in the pathogenesis of diabetic retinopathy (DR). Hypoxia-inducible factor-1 (HIF-1) is the key mediator in cellular oxygen homeostasis that facilitates the adaptation to hypoxia. HIF-1 is repressed by hyperglycemia contributing by this to the development of complications in diabetes. Recent work has shown that the HIF-1A Pro582Ser polymorphism is more resistant to hyperglycemia-mediated repression, thus protecting against the development of diabetic nephropathy. In this study, we have investigated the effect of the HIF-1A Pro582Ser polymorphism on the development of DR and further dissected the mechanisms by which the polymorphism confers a relative resistance to the repressive effect of hyperglycemia.

RESEARCH DESIGN AND METHOD

703 patients with type 1 diabetes mellitus from one endocrine department were included in the study. The degree of retinopathy was correlated to the HIF-1A Pro582Ser polymorphism. The effect of glucose on a stable HIF-1A construct with a Pro582Ser mutation was evaluated in vitro.

RESULTS

We identified a protective effect of HIF-1A Pro582Ser against developing severe DR with a risk reduction of 95%, even when adjusting for known risk factors for DR such as diabetes duration, hyperglycemia, and hypertension. The Pro582Ser mutation does not cancel the destabilizing effect of glucose but is followed by an increased transactivation activity even in high glucose concentrations.

CONCLUSION

The HIF-1A genetic polymorphism has a protective effect on the development of severe DR. Moreover, the relative resistance of the HIF-1A Pro582Ser polymorphism to the repressive effect of hyperglycemia is due to the transactivation activity rather than the protein stability of HIF-1α.

Effects of acute fructose loading on levels of serum uric acid-a pilot study

BACKGROUND

Fructose intake may lead to hyperuricaemia, which is associated with increased risk and progression of kidney disease. We aimed to explore the acute effects of fructose loading from different sources, with and without a pizza, on levels of serum uric acid in patients with chronic kidney disease (CKD), type 2 diabetes (T2D) without CKD, and in healthy subjects (HS).

METHODS

The study included six HS, and three CKD stage 4-5 and seven T2D patients. Drinks consumed were blueberry drink (17.5 g fructose), Coca-Cola (18 g fructose) and fructose drink (35 g fructose). The drinks were also combined with pizza, in total six interventions. Serum samples were collected fasting and 30, 60, 90 and 120 minutes after intake and also 240 minutes after drink + pizza, and analysed for fructose, uric acid and triglycerides. Postprandial responses were explored using repeated-measure ANOVA.

RESULTS

Baseline serum uric acid levels were increased in CKD (P = 0.037). There were significant differences in serum fructose and serum uric levels over time between drinks and drinks + pizza for all groups (P < 0.001 and P < 0.05, respectively). The highest peak in serum fructose followed the fructose drink interventions and the lowest the blueberry drink. The fructose drink interventions gave the highest responses in serum uric acid and the lowest responses followed the blueberry drink. Triglycerides increased following pizza interventions (P < 0.001).

CONCLUSIONS

Intake of fructose increases serum uric acid. The fructose intake via a blueberry drink induced lowest increase and thus may be protective.

Improved glycemic control due to sitagliptin is not related to cortisol or the surrogate marker IGFBP-1 for hepatic insulin sensitivity

IMPORTANCE

Elevated cortisol levels and dysregulated insulin-like growth factor binding protein-1 (IGFBP-1; a marker of hepatic insulin sensitivity) are both related to insulin resistance and glucose abnormalities. It is unknown whether improvement in these parameters is related to improved glucose metabolism during treatment with sitagliptin.

OBJECTIVE

To determine whether improved insulin sensitivity and beta-cell function during treatment with sitagliptin is related to lower cortisol levels and/or improved regulation of IGFBP-1 in patients with recent acute coronary syndrome (ACS) and newly discovered glucose abnormalities.

DESIGN

Samples were taken from The BEta-cell function in Glucose abnormalities and Acute Myocardial Infarction (BEGAMI) trial, a double-blinded, placebo-controlled randomized clinical trial on the efficacy and safety of sitagliptin for patients with ACS and newly discovered glucose abnormalities.

SETTING

Cardiology departments (cardiac ICU and outpatient clinic) in two hospitals in Stockholm, Sweden.

PARTICIPANTS

Subjects hospitalized (or recently hospitalized) for ACS, in whom an oral glucose tolerance test revealed previously unknown glucose abnormalities.

INTERVENTIONS

Subjects were randomized to sitagliptin 100mg once daily (n=34) or placebo (n=37) for twelve weeks. Oral glucose tolerance test (OGTT) and randomization occurred after stabilization median 7 days after ACS.

MAIN OUTCOMES AND MEASURES

Fasting serum cortisol and IGFBP-1 were analyzed before OGTT, around 8a.m., and after at 10a.m. The latter time point was chosen as the spread in cortisol levels around is small then, allowing improved chances to detect differences between groups.

RESULTS

Glucose tolerance and insulin sensitivity improved in both groups, while HbA1c and indices of β-cell function improved only in the sitagliptin group as reported previously. Both groups displayed decreased cortisol levels around 10a.m. (from 338±21 to 278±14 nmol/L, p=0.038, in the sitagliptin group; from 343±17 to 302±15 nmol/L, p=0.017, in the placebo group), and improved correlation between fasting log-IGFBP-1 and insulin.

CONCLUSIONS AND RELEVANCE

These findings suggest that a stress-related elevation in cortisol may have negative impact on glucose tolerance in patients with recent ACS. However, improved glycemic control with sitagliptin does not appear to be related to changes in cortisol levels or hepatic insulin sensitivity as assessed by IGFBP-1.

Gender difference in adrenal sensitivity to ACTH is abolished in type 2 diabetes

OBJECTIVE

Dysfunction of the hypothalamus-pituitary-adrenal (HPA) axis has been implicated in type 2 diabetes (T2D). The aim of this study was to investigate the impact of T2D and gender on the HPA axis.

METHODS

Synthetic ACTH (1 μg) was administered to 21 subjects with T2D (age 62 (54-70) years, 11 men/ten women, HbA1c 49±2 mmol/mol, treated with diet or oral antidiabetic drugs) and 38 controls (age 58 (41-67) years, 20 men/18 women). Fasting basal B-glucose, serum cortisol, insulin, IGF1 and IGFBP1 concentrations were measured, and sampling for all but IGF1 was repeated 30, 60, and 90 min after ACTH injection. Patients took 0.25 mg dexamethasone at 2200-2300 h and returned the next morning for the measurement of serum cortisol concentration.

DESIGN

Cross-sectional study.

RESULTS

Patients with T2D had similar fasting serum cortisol, IGF1 and IGFBP1 concentrations; however, serum cortisol concentration after administration of dexamethasone did not differ between the groups. Healthy women exhibited higher peak cortisol levels compared with healthy men (675±26 vs 582±21 nmol/l, P=0.014), while the peak levels were equally high in men and women with T2D, resulting in a higher peak level in men with T2D compared with healthy men (691±42 vs 582±21 nmol/l, P=0.024). Serum cortisol concentration after administration of dexamethasone did not differ between the groups, nor did IGF1 and IGFBP1.

NOVELTY OF THE FINDINGS

Some studies have previously indicated disturbed regulation of the hypothalamus-pituitary-adrenal (HPA) axis in subjects with type 2 diabetes (T2D); however, much remains unknown in this area. To the best of our knowledge, this is the first study to show that the gender difference in the adrenal response to ACTH (with greater reactivity in women) is abolished in T2D. While the clinical implications cannot be determined by this paper, it is known that gender differences exist in the pathogenesis and complications of T2D. Thus, our findings suggest that further research into gender differences in the HPA axis is warranted.

CONCLUSIONS

Gender differences in adrenal response to ACTH were abolished in T2D. Men with T2D had a higher peak cortisol compared with controls. Further studies are needed to elucidate the clinical implications.

Markers of innate immune activity in patients with type 1 and type 2 diabetes mellitus and the effect of the anti-oxidant coenzyme Q10 on inflammatory activity

Major long-term complications in patients with diabetes are related to oxidative stress, caused by the hyperglycaemia characteristic for diabetes mellitus. The anti-oxidant coenzyme Q10 (CoQ10) has therefore been proposed as a beneficial supplement to diabetes treatment. Apart from its anti-oxidative function, CoQ10 appears to modulate immune functions by largely unknown mechanisms. The aim of this study was therefore to investigate the effect of CoQ10 on antimicrobial peptides and natural killer (NK) cells, both innate immune components implicated in the pathogenesis of diabetes and diabetes-associated long-term complications such as cardiovascular disease. We determined serum levels of antimicrobial peptides and the phenotype of NK cells isolated from peripheral blood of patients with type 1 (T1DM) or type 2 diabetes mellitus (T2DM) and from healthy controls. In addition, the same parameters were determined in diabetic patients after a 12-week period of CoQ10 supplementation. Two antimicrobial peptides, the human cathelicidin antimicrobial peptide (CAMP) and the human beta defensin 1 (hBD1), were reduced in serum from patients with T1DM. This defect was not reversible by CoQ10 supplementation. In contrast, CoQ10 reduced the levels of circulating hBD2 in these patients and induced changes in subset distribution and activation markers in peripheral NK cells. The results of the present study open up novel approaches in the prevention of long-term complications associated to T1DM, although further investigations are needed.

Plasma glutaredoxin activity in healthy subjects and patients with abnormal glucose levels or overt type 2 diabetes

Oxidative stress induced by hyperglycemia is a key factor in the pathogenesis of diabetes complications. Glutaredoxin 1(Grx1) is a cytosolic redox protein that catalyzes GSH-dependent thiol redox reactions and reversible protein S-glutathionylation. In humans, Grx1 antigen has previously been detected in plasma; however, it has hitherto been unclear if plasma Grx1 is enzymatically active, which would indicate an extracellular function of the protein. Given that glucose overload damages cells through oxidative stress responses, we investigated whether postprandial hyperglycemia induces changes in extracellular Grx1 in patients with abnormal glucose tolerance and healthy subjects. Using a novel sensitive fluorescent substrate assay, we demonstrated that plasma Grx consists of active protein. Grx antigen, activity and total antioxidant capacity were significantly elevated in patients compared to healthy subjects. In response to oral glucose tolerance test, Grx activity and antioxidant capacity increased significantly in healthy volunteers, however, not to the high levels of the patients. In conclusion, these results indicate an extracellular function of plasma Grx in blood glucose metabolism. Thus, Grx may be a marker of increased oxidative stress during hyperglycemia in healthy subjects and may be a risk marker of progression toward diabetes onset.

Gender differences in non-glycemic responses to improved insulin sensitivity by pioglitazone treatment in patients with type 2 diabetes

Excess cortisol and GH induce insulin resistance, a central feature of type 2 diabetes (T2D). To study whether the insulin sensitizer pioglitazone affects basal cortisol levels and the GH-IGF-I axis in patients with T2D. Forty-eight patients with T2D (men/women = 28:20, age 61 ± 1 years, BMI 31 ± 0.6 kg/m(2)) were treated for 26 weeks with pioglitazone 30-45 mg daily in addition to their preexisting therapy. Insulin, proinsulin, HbA(1c), IGF-I, IGFBP-1, and basal cortisol were analyzed before and after treatment. Pioglitazone decreased proinsulin/insulin ratio and HbA(1c) decreased (HbA(1c) from 7.8 ± 0.2 to 6.6 ± 0.2% in men and from 7.6 ± 0.2 to 6.1 ± 0.2% in women, p < 0.001 in both). There was a redistribution of fat but no change in waist circumference. IGF-I and adiponectin increased (p ≤ 0.001) in both genders. IGFBP-1 increased but significantly only for the whole group (p = 0.033). Triglycerides decreased significantly in women only (p = 0.015). Before treatment, women had lower basal cortisol (p = 0.045). Basal cortisol increased in women (from 390 ± 26 to 484 ± 32 nmol/L, p = 0.020) but not in men and did not differ between genders at week 26. ΔIGFBP-1 correlated with Δcortisol (r = 0.458; p = 0.049) and Δadiponectin (r = 0.600; p = 0.005) in women only. In addition to the known effect of improving insulin sensitivity, pioglitazone increased IGF-I regardless of gender and in women also increased basal cortisol. Increased IGF-I may contribute to improved insulin sensitivity after treatment. There seems to be gender differences in treatment responses to pioglitazone on lipid metabolism and basal cortisol, perhaps correcting different mechanisms of insulin resistance between genders.

Sex differences in type 2 diabetes: focus on disease course and outcomes

BACKGROUND

Women with type 2 diabetes (T2D) are less likely to reach the goals for hemoglobin A1c compared with men, and have higher all-cause mortality. The risk of cardiovascular disease is elevated among both men and women with T2D, however, the risk has declined among men over recent years while it remains stationary in women. Reasons for these sex differences remain unclear, and guidelines for diabetes treatment do not differentiate between sexes. Possible causes for varying outcome include differences in physiology, treatment response, and psychological factors. This review briefly outlines sex differences in hormonal pathophysiology, and thereafter summarizes the literature to date on sex differences in disease course and outcome.

METHODS

Systematic searches were performed on PubMed using "sex", "gender", and various glucose-lowering therapies as keywords. Earlier reviews are summarized and results from individual studies are reported. Reference lists from studies were used to augment the search.

RESULTS

There is an increased risk of missing the diagnosis of T2D when screening women with only fasting plasma glucose instead of with an oral glucose tolerance test. The impact of various risk factors for complications may differ by sex. Efficacy and side effects of some glucose-lowering drugs differ between men and women. Men with T2D appear to suffer more microvascular complications, while women have higher morbidity and mortality in cardiovascular disease and also fare worse psychologically.

CONCLUSION

Few studies to date have focused on sex differences in T2D. Several questions demand further study, such as whether risk factors and treatment guidelines should be sex-specific. There is a need for clinical trials designed specifically to evaluate sex differences in efficacy and outcome of the available treatments.

Analyte flux at a biomaterial-tissue interface over time: implications for sensors for type 1 and 2 diabetes mellitus

OBJECTIVE

The very presence of an implanted sensor (a foreign body) causes changes in the adjacent tissue that may alter the analytes being sensed. The objective of this study was to investigate changes in glucose availability and local tissue metabolism at the sensor-tissue interface in patients with type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM).

METHOD

Microdialysis was used to model implanted sensors. Capillary glucose and subcutaneous (sc) microdialysate analytes were monitored in five T1DM and five T2DM patients. Analytes included glucose, glycolysis metabolites (lactate, pyruvate), a lipolysis metabolite (glycerol), and a protein degradation byproduct (urea). On eight consecutive days, four measurements were taken during a period of steady state blood glucose.

RESULTS

Microdialysate glucose and microdialysate-to-blood-glucose ratio increased over the first several days in all patients. Although glucose recovery eventually stabilized, the lactate levels continued to rise. These trends were explained by local inflammatory and microvascular changes observed in histological analysis of biopsy samples. Urea concentrations mirrored glucose trends. Urea is neither produced nor consumed in sc tissue, and so the initially increasing urea trend is explained by increased local capillary presence during the inflammatory process. Pyruvate in T2DM microdialysate was significantly higher than in T1DM, an observation that is possibly explained by mitochondrial dysfunction in T2DM. Glycerol in T2DM microdialysate (but not in T1DM) was higher than in healthy volunteers, which is likely explained by sc insulin resistance (insulin is a potent antilipolytic hormone). Urea was also higher in microdialysate of patients with diabetes mellitus compared to healthy volunteers. Urea is a byproduct of protein degradation, which is known to be inhibited by insulin. Therefore, insulin deficiency or resistance may explain the higher urea levels. To our knowledge, this is the first histological evaluation of a human tissue biopsy containing an implanted glucose monitoring device.

CONCLUSIONS

Monitoring metabolic changes at a material-tissue interface combined with biopsy histology helped to formulate an understanding of physiological changes adjacent to implanted glucose sensors. Microdialysate glucose trends were similar over 1-week in T1DM and T2DM; however, differences in other analytes indicated wound healing and metabolic activities in the two patient groups differ. We propose explanations for the specific observed differences based on differential insulin insufficiency/resistance and mitochondrial dysfunction in T1DM versus T2DM.