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Glycemic Monitoring and Prediction With Response Improvement via Psyllium

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Abstract

Fibers are proven to provide health benefits in preventing metabolic diseases. This chapter first presents the existing blood glucose monitoring sensors and a prediction model for blood glucose concentration. It also aims at analyzing the efficacy of a functional fiber, psyllium on the glycemic control function. Three studies included suggesting psyllium supplementation would significantly improve glycemic response while two studies included showed no effects. Advantages and limitations of each study were evaluated. Overall, it is generally believed that psyllium might give glycemic response improvement effect, especially in Type II Diabetes Mellitus patients.

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Background and objective: Nocturnal hypoglycemia (NH) is common in patients with insulin-treated diabetes. Despite the risk associated with NH, there are only a few methods aiming at the prediction of such events based on intermittent blood glucose monitoring data and none has been validated for clinical use. Here we propose a method of combining several predictors into a new one that will perform at the level of the best involved one, or even outperform all individual candidates. Methods: The idea of the method is to use a recently developed strategy for aggregating ranking algorithms. The method has been calibrated and tested on data extracted from clinical trials, performed in the European FP7-funded project DIAdvisor. Then we have tested the proposed approach on other datasets to show the portability of the method. This feature of the method allows its simple implementation in the form of a diabetic smartphone app. Results: On the considered datasets the proposed approach exhibits good performance in terms of sensitivity, specificity and predictive values. Moreover, the resulting predictor automatically performs at the level of the best involved method or even outperforms it. Conclusion: We propose a strategy for a combination of NH predictors that leads to a method exhibiting a reliable performance and the potential for everyday use by any patient who performs self-monitoring of blood glucose.
Article
Background: In type 1 diabetes (T1D) management, short-term glucose prediction can allow to anticipate therapeutic decisions when hypo/hyperglycemia is imminent. Literature prediction methods mainly use past continuous glucose monitoring (CGM) readings. Sophisticated algorithms can use information on insulin delivered and meal carbohydrate (CHO) content. The quantification of how much insulin and CHO information improves glucose prediction is missing in the literature and is investigated, in an open-loop setting, in this proof-of-concept study. Methods: We adopted a versatile literature prediction methodology able to utilize a variety of inputs. We compared predictors that use (1) CGM; (2) CGM and insulin; (3) CGM and CHO; and (4) CGM, insulin, and CHO. Data of 15 T1D subjects in open-loop setup were used. Prediction was evaluated via absolute error and temporal gain focusing on meal/night periods. The relative importance of each individual input of the predictor was evaluated with a sensitivity analysis. Results: For a prediction horizon (PH) ≥ 30 minutes, insulin and CHO information improves prediction accuracy of 10% and double the temporal gain during the 2 hours following the meal. During the night the 4 methods did not give statistically different results. When PH ≥ 45 minutes, the influence of CHO information on prediction is 5-fold that of insulin. Conclusions: In an open-loop setting, with PH ≥ 30 minutes, information on CHO and insulin improves short-term glucose prediction in the 2-hour time window following a meal, but not during the night. CHO information improves prediction significantly more than insulin.
Article
Owing to its high carrier mobility, conductivity, flexibility and optical transparency, graphene is a versatile material in micro- and macroelectronics. However, the low density of electrochemically active defects in graphene synthesized by chemical vapour deposition limits its application in biosensing. Here, we show that graphene doped with gold and combined with a gold mesh has improved electrochemical activity over bare graphene, sufficient to form a wearable patch for sweat-based diabetes monitoring and feedback therapy. The stretchable device features a serpentine bilayer of gold mesh and gold-doped graphene that forms an efficient electrochemical interface for the stable transfer of electrical signals. The patch consists of a heater, temperature, humidity, glucose and pH sensors and polymeric microneedles that can be thermally activated to deliver drugs transcutaneously. We show that the patch can be thermally actuated to deliver Metformin and reduce blood glucose levels in diabetic mice.
Article
This study of the effect of Metamucil in non-insulin-dependent diabetics revealed similar results as previously reported after the administration of other gel-forming fibres. Hitherto, studies have been made on the effect of LDL and HDL with diverging results. In this study, HDL was not significantly reduced after four months of treatment. Bran is probably relatively equal to the bulk laxatives in the treatment of constipation, but apparently bran lacks the effect on lipid and carbohydrate metabolism produced by the gel-forming fibres. Metamucil, being a mucilloid agent, in this study was proved to possess a significant long-acting reducing effect on fasting blood glucose and serum cholesterol.
Article
Abstract A major challenge for a person with diabetes is to adapt insulin dosage regimens and food intake to keep blood glucose within tolerable limits during daily life activities. The early knowledge about the effects of inputs on glycemia would provide the patients with invaluable information for appropriate on-the-spot decision making concerning the management of the disease. Against this background, in this paper we propose multi-step data-driven predictors to the purpose of predicting blood glucose multiple steps ahead in the future, supporting therefore the patients when deciding upon treatments. We formulate the predictors based on the state-space construction step in subspace identification methods for linear systems. Physiological models from the literature were used to filter the raw information on carbohydrate and insulin intakes in order to retrieve the input signals to the predictors. The clinical data of 14 type 1 diabetic patients collected in hospital during a 3-days long visit were used. Half of the data were employed for predictor development and the remaining half for validation. Mean population prediction error standard deviation on 30 min, 60 min, 90 min, 120 min ahead prediction on validation data resulted in, respectively, 19.17 mg/dL, 37.99 mg/dL, 50.62 mg/dL and 58.06 mg/dL.
Article
A high dietary fiber (DF) intake is emphasized in the recommendations of most diabetes and nutritional associations. It is accepted that viscous and gel-forming properties of soluble DF inhibit macronutrient absorption, reduce postprandial glucose response, and beneficially influence certain blood lipids. Colonic fermentation of naturally available high fiber foods can also be mainly attributed to soluble DF, whereas no difference between soluble and insoluble DF consumption on the regulation of body weight has been observed. However, in prospective cohort studies, it is primarily insoluble cereal DF and whole grains, and not soluble DF, that is consistently associated with reduced diabetes risk, suggesting that further, unknown mechanisms are likely to be involved. Recent research indicates that DF consumption contributes to a number of unexpected metabolic effects independent from changes in body weight, which include improvement of insulin sensitivity, modulation of the secretion of certain gut hormones, and effects on various metabolic and inflammatory markers that are associated with the metabolic syndrome. In this review, we briefly summarize novel findings from recent interventions and prospective cohort studies. We discuss concepts and potential mechanisms that might contribute to the further understanding of the involved processes.
Article
Dietary fiber that is intrinsic and intact in fiber-rich foods (eg, fruits, vegetables, legumes, whole grains) is widely recognized to have beneficial effects on health when consumed at recommended levels (25 g/d for adult women, 38 g/d for adult men). Most (90%) of the US population does not consume this level of dietary fiber, averaging only 15 g/d. In an attempt to bridge this "fiber gap," many consumers are turning to fiber supplements, which are typically isolated from a single source. Fiber supplements cannot be presumed to provide the health benefits that are associated with dietary fiber from whole foods. Of the fiber supplements on the market today, only a minority possess the physical characteristics that underlie the mechanisms driving clinically meaningful health benefits. In this 2-part series, the first part (previous issue) described the 4 main characteristics of fiber supplements that drive clinical efficacy (solubility, degree/rate of fermentation, viscosity, and gel formation), the 4 clinically meaningful designations that identify which health benefits are associated with specific fibers, and the gel-dependent mechanisms in the small bowel that drive specific health benefits (eg, cholesterol lowering, improved glycemic control). The second part (current issue) of this 2-part series will focus on the effects of fiber supplements in the large bowel, including the 2 mechanisms by which fiber prevents/relieves constipation (insoluble mechanical irritant and soluble gel-dependent water-holding capacity), the gel-dependent mechanism for attenuating diarrhea and normalizing stool form in irritable bowel syndrome, and the combined large bowel/small bowel fiber effects for weight loss/maintenance. The second part will also discuss how processing for marketed products can attenuate efficacy, why fiber supplements can cause gastrointestinal symptoms, and how to avoid symptoms for better long-term compliance.
Article
Glucose concentration in type 1 diabetes is a function of biological and environmental factors which present high inter-patient variability. The objective of this study is to evaluate a number of features, which are extracted from medical and lifestyle self-monitoring data, with respect to their ability to predict the short-term subcutaneous (s.c.) glucose concentration of an individual. Random forests (RF) and RReliefF algorithms are first employed to rank the candidate feature set. Then, a forward selection procedure follows to build a glucose predictive model, where features are sequentially added to it in decreasing order of importance. Predictions are performed using support vector regression or Gaussian processes. The proposed method is validated on a dataset of 15 type diabetics in real-life conditions. The s.c. glucose profile along with time of the day and plasma insulin concentration are systematically highly ranked, while the effect of food intake and physical activity varies considerably among patients. Moreover, the average prediction error converges in less than d/2 iterations (d is the number of features). Our results suggest that RF and RReliefF can find the most informative features and can be successfully used to customize the input of glucose models.
Article
We used the Cochran Q test to evaluate heterogeneity between studies and considered a threshold P value less than 0.1 as statistically significant. We also did I² testing to evaluate the magnitude of the heterogeneity between studies (11). We calculated pooled estimates of the mean differences in HbA1c level and weight between intervention groups by using a random-effects model (DerSimonian–Laird method) to adequately account for the additional uncertainty associated with study–study variability in the effect of different agents. We used random-effects meta-regression analyses to assess whether diabetes duration, baseline HbA1c level, baseline body mass index (BMI), and industry funding were potential sources of heterogeneity by using the restricted maximum likelihood estimator. We chose variables on the basis of previous data (12–13) or biological relevance before the meta-analysis was undertaken. We assessed the possibility of publication bias by using a funnel plot of each trial's effect size against the SE. We evaluated funnel plot asymmetry by using Begg and Egger tests and defined significant publication bias as a P value less than 0.1 (14). The direct meta-analysis was done by using Stata statistical software, version 11.0 (StataCorp, College Station, Texas). In this meta-analysis of trials evaluating the effects of adding a third antihyperglycemic agent to metformin and sulfonylurea therapy for patients with type 2 diabetes, we report an overall reduction of HbA1c level of −0.96%, a finding similar to that of a recent network meta-analysis (7) that reported an overall reduction of HbA1c level of −0.62% to −1.00% when a second drug was added to metformin therapy. We found no clear statistically significant differences in the degree of reduction of HbA1c level by drug class in direct and indirect comparisons, also confirming findings from the previous analysis, although it did not evaluate insulin efficacy (7). A similar decrease (−0.5% to −1.25%) was seen in a meta-analysis comparing the effect of adding a single oral antidiabetic agent (GLP-1 agonists and insulins were not evaluated) versus placebo in participants who either were drug-naive or were receiving background therapy with an oral antidiabetic agent with or without insulin (13). Taken together, these findings suggest that addition of a third antihyperglycemic agent provides useful additional glycemic control for patients who are already receiving metformin and a sulfonylurea. The available limited evidence does not clearly identify a preferred antihyperglycemic drug class among drugs represented in clinical trials (thiazolidinediones, GLP-1 agonists, dipeptidyl peptidase-4 inhibitors, insulins, and acarbose). Glucagon-like peptide-1 agonists led to more weight loss than other agents and might be chosen as a third agent on that basis, but they also were associated with more severe hypoglycemic reactions than any other drug class except insulin.
Article
Objective This double-blind, placebo-controlled clinical study was designed to evaluate the effects of psyllium on fasting blood glucose (FBG) and HbA1c in patients being treated for type-2 diabetes mellitus (T2DM).Research design and methodsPatients were randomly assigned to 1 of the 3 treatment groups: placebo, psyllium 3.4 g BID or psyllium 6.8 g BID (just prior to breakfast and dinner). Patients had a total of 9 clinic visits during the 20-week study period (8 weeks baseline, 12 weeks treatment). A total of 37 patients [12 females, 34 Caucasians, mean age 62 years] were enrolled (8 in the placebo group, 15 in the psyllium 3.4 g BID group and 14 in the psyllium 6.8 g BID group) and were included in the Intent-to-Treat analysis.ResultsBoth doses of psyllium significantly (p<0.05) lowered FBG compared to placebo at treatment weeks 4, 8, and 12. Psyllium 6.8 g BID significantly lowered HbA1c compared to placebo at Week 8 (−0.58±0.18, p=0.003), and both the 3.4 g dose and the 6.8 g dose of psyllium significantly (p<0.05) lowered HbA1c compared to placebo at Week 12 (−0.53±0.20, p=0.013; −0.65±0.20, p=0.003, respectively).Conclusions The improvement in glycemic control observed with psyllium in T2DM patients was above that already conferred by a restricted diet (all patients) and a stable dose of a sulfonylurea (81.1% of patients). These data support that psyllium is an effective co-therapy for improving glycemic control in patients being treated for T2DM. NCT01582282.
Article
Background: Hypoglycemia prevention is one of the major challenges in diabetes research. Recently, it has been suggested that continuous glucose monitoring (CGM)-based short-term glucose prediction algorithms could be exploited to generate alerts when hypoglycemia is forecasted, allowing the patient to take appropriate countermeasures to avoid/mitigate the event. However, quantifying the potential benefits of prediction in terms of reduction of number/duration of hypoglycemia requires an in silico assessment that is the object of the present article. Materials and methods: Data for 50 virtual subjects were generated by using the University of Virginia/Padova type 1 diabetes simulator (54-h monitoring), made more credible by adding realistic measurement noise and perturbations of meals and insulin injections. CGM was assumed to be well calibrated. Occurrence and duration of hypoglycemic events were compared in three scenarios: (1) hypoglycemia was not recognized and not dealt with; (2) 15 g of carbohydrates was ingested when CGM crossed the hypoglycemia threshold; or (3) 15 g of carbohydrates was ingested when the 30-min ahead-of-time CGM prediction crossed the hypoglycemia threshold. The effectiveness of alerts was investigated also in the case of delayed/absent ingestion of carbohydrates. Results: In Scenario 1, each virtual subject spent 17.7% of the time in the hypoglycemic range, with a median of four events of 120 min in the 54-h period monitored. In Scenario 2, the time spent in hypoglycemia was reduced to 4.7% (four events of 40 min). In Scenario 3, the time spent in hypoglycemia was further reduced to 1.2% (one event of 15 min). Absent/delayed patient's responses to alerts slightly increase these percentages, but improvements remain significant. Conclusions: This in silico proof-of-concept study demonstrates that using predicted rather than measured CGM allows a significant reduction of the number of hypoglycemic events and the time spent in hypoglycemic range both by 75%, stimulating further research and clinical investigation on the generation of preventive hypoglycemic alerts exploiting glucose prediction methods.
Article
Psyllium (two husk sizes), methylcellulose (three viscosity grades), pectin, and Solka Floc® were fermented in vitro with human fecal inoculum for 4, 12, and 24 h to assess organic matter disappearance (OMD), short chain fatty acid (SCFA) production, and gas production and composition. Substrate OMD was greatest for pectin following by methylcellulose, psyllium, and Solka Floc®. Pectin fermentation produced the highest total SCFA followed by psyllium, Solka Floc®, and methylcellulose. Total gas production correlated well with SCFA production and ranged from 108.1 (pectin) to 0.57 (methylcellulose 15) mL/g OM. Differences in SCFA and gas production may affect clinical properties; therefore, fermentative characteristics of fibrous ingredients should be considered when evaluating the fiber sources for supplementation purposes.
Article
The evidence of the relationship between fiber intake and control of diabetes is mixed. The purpose of this study was to determine if an increase in dietary fiber affects glycosylated hemoglobin (HbA1c) and fasting blood glucose in patients with type 2 diabetes mellitus. Randomized studies published from January 1, 1980, to December 31, 2010, that involved an increase in dietary fiber intake as an intervention, evaluated HbA1c and/or fasting blood glucose as an outcome, and used human participants with known type 2 diabetes mellitus were selected for review. Fifteen studies met inclusion and exclusion criteria. The overall mean difference of fiber versus placebo was a reduction of fasting blood glucose of 0.85 mmol/L (95% CI, 0.46-1.25). Dietary fiber as an intervention also had an effect on HbA1c over placebo, with an overall mean difference of a decrease in HbA1c of 0.26% (95% CI, 0.02-0.51). Overall, an intervention involving fiber supplementation for type 2 diabetes mellitus can reduce fasting blood glucose and HbA1c. This suggests that increasing dietary fiber in the diet of patients with type 2 diabetes is beneficial and should be encouraged as a disease management strategy.
Article
Dietary fiber intake provides many health benefits. However, average fiber intakes for US children and adults are less than half of the recommended levels. Individuals with high intakes of dietary fiber appear to be at significantly lower risk for developing coronary heart disease, stroke, hypertension, diabetes, obesity, and certain gastrointestinal diseases. Increasing fiber intake lowers blood pressure and serum cholesterol levels. Increased intake of soluble fiber improves glycemia and insulin sensitivity in non-diabetic and diabetic individuals. Fiber supplementation in obese individuals significantly enhances weight loss. Increased fiber intake benefits a number of gastrointestinal disorders including the following: gastroesophageal reflux disease, duodenal ulcer, diverticulitis, constipation, and hemorrhoids. Prebiotic fibers appear to enhance immune function. Dietary fiber intake provides similar benefits for children as for adults. The recommended dietary fiber intakes for children and adults are 14 g/1000 kcal. More effective communication and consumer education is required to enhance fiber consumption from foods or supplements.
Article
Thirty-six children identified as having primary type IIa hypercholesterolemia were treated with a diet restricting the intake of saturated fat to 10% of total energy and supplemented with soluble fiber for 8.1 +/- 2.4 (mean +/- SEM) months. In 14 of 36 patients first treated with the American Heart Association "Step-One" diet for 8.0 +/- 1.1 months, total cholesterol level dropped from 257.9 +/- 15.8 mg/dL to 240.6 +/- 10.9 mg/dL; the low-density lipoprotein cholesterol level dropped from 191.8 +/- 17.4 mg/dL to 175.0 +/- 11.7 mg/dL; the high-density lipoprotein cholesterol level dropped from 42.8 +/- 1.94 mg/dL to 41.6 +/- 1.68 mg/dL; and triglyceride concentration rose from 115.9 +/- 13.7 mg/dL to 128.1 +/- 14.1 mg/dL. The 36 patients treated with saturated fat-restrictive diets and supplemental soluble fiber diets had a reduction of total cholesterol levels from 249.2 +/- 7.66 mg/dL to 207.1 +/- 6.31 mg/dL and a low-density lipoprotein cholesterol level reduction from 184.7 +/- 7.55 mg/dL to 142.6 +/- 6.7 mg/dL, a reduction of 18% and 23%, respectively. There was no significant change in high-density lipoprotein cholesterol levels (46.4 +/- 1.9 mg/dL vs 44.3 +/- 2.1 mg/dL) or in triglyceride concentrations (94.2 +/- 7.43 mg/dL vs 102.2 +/- 8.45 mg/dL). In addition, the reduction in serum lipoprotein concentrations resulting from this program was significantly greater than the concentrations resulting from the American Heart Association diet alone. The different responses to these regimens suggest that a simplified diet and soluble fiber supplementation is well tolerated and reduces total and low-density lipoprotein cholesterol levels more effectively than the standard American Heart Association diet in children.
Article
The effect of consumption of isabgol husk for 3 weeks on faecal excretion and serum levels of lipids was investigated in 11 adolescent girls. The consumption of isabgol husk lowered serum lipids and increased faecal fat.
Article
The effect of the administration of 3.5 g of psyllium husk twice daily for 90 days was investigated in 24 patients of non insulin dependent diabetes mellitus (NIDDM) with hyperlipidaemia. After 90 days of treatment, psyllium was withdrawn and the patients were followed up for a further 90 days. Psyllium significantly decreased the levels of total cholesterol (TC; 19.7%), low-density lipoprotein cholesterol (LDL-C; 23.7%), triglycerides (TG; 27.2%) and the ratio of LDL-C to high-density lipoprotein cholesterol (HDL-C; 24.1%) and the lowering was sustained even up to 90 days after cessation of treatment. The level of HDL-C also showed a significant increase of 15.8 per cent but this effect was not sustained after cessation of treatment. The compliance was very good and no adverse effects were observed. This study indicated that psyllium husk is an effective and well tolerated adjunct to diet for the treatment of mild to moderate hyperlipidaemia in NIDDM patients.
Article
The aim of the current study was to characterize the effects of isolated and native sources of beta-glucan, oat gum, and oat bran, respectively, when incorporated into a complete meal. Fasting control subjects and subjects with Type 2 diabetes were fed porridge meals containing either wheat farina, wheat farina plus oat gum or oat bran. Blood samples were collected for 3 h after the test meals and plasma glucose and insulin were measured. Oat bran and wheat farina plus oat gum meals reduced the postprandial plasma glucose excursions and insulin levels when compared with the control wheat farina meal in both control and Type 2 diabetic subjects. This study shows that both the native cell wall fibre of oat bran and isolated oat gum, when incorporated into a meal, act similarly by lowering postprandial plasma glucose and insulin levels. A diet rich in beta-glucan may therefore be of benefit in the regulation of postprandial plasma glucose levels in subjects with Type 2 diabetes.
Article
The diet of six normal and five ileostomy subjects was supplemented with 10 g/d Plantago ovata psyllium husk for 3 wk while six normal and four ileostomy subjects received 10 g/d psyllium seed. Fecal and ileostomy output, sterol excretion, serum cholesterol, and triglycerides were measured before and after supplementation. The husk had no effect on cholesterol or triglyceride concentrations in either normal or ileostomy subjects. Total and high-density-lipoprotein-cholesterol concentrations were reduced on average by 6.4% and 9.3%, respectively, in the normal group after seed supplementation. No effect on fecal bile acid excretion in the normal subjects was found after both regimes. Ileostomy bile acids were increased (on average 25%) after seed supplementation, whereas no effect on cholesterol concentrations was found. These results suggest that psyllium seed might be more effective than the husk in reducing serum cholesterol, that this cholesterol-lowering effect is not mediated by increased fecal bile acid losses, and increased ileal losses of bile acids might be compensated for by enhanced reabsorption in the colon.
Article
Several dietary fibre-rich substrates were fermented in vitro with human colonic bacteria obtained from each of three adult male subjects to assess the extent of substrate fermentation short-chain fatty acid (SCFA) production, and the potential effect of fermented residues on faecal bulk. Substrates tested were two varieties of oat hull fibre, gum arabic, carboxymethylcellulose (CMC), soy fibre, psyllium, and six blends containing oat fibre, gum arabic, and CMC in various proportions. All substrates contained greater than 900 g/kg of total dietary fibre except for CMC (816 g) and soy fibre (778 g). In vitro organic matter disappearance during fermentation was greatest for gum arabic (69.5%), intermediate for soy fibre (56.4%), and less than 20% for the two oat fibres, CMC, and psyllium. Averaged across substrates, acetate, propionate, and butyrate were produced in the molar proportion of 64:24:12. Potential water-holding capacity (PWHC) of substrates, a measure of faecal bulking potential, was greatest for CMC (13.5 g H2O/g substrate) and lowest for gum arabic (1.92 g) and soy fibre (1.71 g). Organic matter disappearance and SCFA production of blends were directly proportional to their gum arabic content. Blend PWHC was proportional to CMC content. In vitro procedures are useful in predicting the actions of fibre blends formulated to produce desirable effects in vivo.
Article
A randomized, double-blind, placebo-controlled, crossover clinical trial was designed to test the efficacy of psyllium fiber in lowering elevated low-density lipoprotein cholesterol (LDL-C) levels in children 5 to 17 years of age. Subjects with LDL-C levels > 2.84 mmol/L (110 mg/dl) after at least 3 months of a low total fat, low saturated fat, low cholesterol diet were enrolled. Two ready-to-eat cereals, with water-soluble psyllium fiber (6 gm/day) and without, were prescribed for 4 to 5 weeks each, with an intervening 2-week washout phase. Reported compliance rates exceeded 80% in the 20 subjects who completed the study. Mean initial total cholesterol, LDL-C, high-density lipoprotein cholesterol, and triglyceride values were 5.23, 3.60, 1.18, and 2.22 mmol/L, respectively. Comparison of the mean changes (from baseline) in lipid values after the two periods of cereal consumption revealed no statistically nor clinically significant differences in total cholesterol, LDL-C, or high-density lipoprotein cholesterol values. Triglyceride levels, however, increased 0.68 mmol/L (26 mg/dl; p < 0.05) after the control cereal in comparison with the psyllium cereal. No significant differences were noted in the children's dietary intake (assessed by 7-day diet records) during the two study periods. Measures of growth (height, weight, and skin-fold thicknesses), and blood vitamin (folic acid; vitamins A, D, and E) and mineral (iron, zinc, and calcium) levels were not affected. In this study, psyllium fiber had no additional lowering effect on total cholesterol or LDL-C levels in children who were already following low total fat, low saturated fat, low cholesterol diets.
Article
A device providing frequent, automatic, and non-invasive glucose measurements for persons with diabetes has been developed: the GlucoWatch biographer. This device extracts glucose through intact skin via reverse iontophoresis where it is detected by an amperometric biosensor. The biographer can provide glucose readings every 20 min for 12 h. The performance of this device was evaluated in two large clinical studies in a controlled clinical environment (n=231), and the home environment (n=124). Accuracy of the biographer was evaluated by comparing the automatic biographer readings to serial finger-stick blood glucose (BG) measurements. Biographer performance was comparable in both environments. Mean difference between biographer and finger-stick measurements was -0.01 and 0.26 mmol l(-1) for the clinical and home environments, respectively. The mean absolute value of the relative difference was 1.06 and 1.18 mmol l(-1) for the same studies. Correlation coefficient (r) between biographer and finger-stick measurements was 0.85 and 0.80 for the two studies. In both studies, over 94% of the biographer readings were in the clinically acceptable A+B region of the Clarke Error Grid. A slight positive bias is observed for the biographer readings at low BG levels. Biographer accuracy is relatively constant over all rates of BG changes, except when BG decreases more than 10 mmol l(-1) h(-1), which occurred for only 0.2% of points in the home environment study. Biographer precision, as measured by CV%, is approx. 10%. Skin irritation, characterized by erythema and edema, was either non-existent or mild in >90% of subjects and resolved in virtually all subjects without treatment in several days.