Joost B. L. Hoekstra

Glucose variability is associated with intensive care unit mortality.

Objective:Mounting evidence suggests a role for glucose variability in predicting intensive care unit (ICU) mortality. We investigated the association between glucose variability and intensive care unit and in-hospital deaths across several ranges of mean glucose. Design:Retrospective cohort study. Setting:An 18-bed medical/surgical ICU in a teaching hospital. Patients:All patients admitted to the ICU from January 2004 through December 2007. Interventions:None. Measurements and Main Results:Two measures of variability, mean absolute glucose change per hour and sd, were calculated as measures of glucose variability from 5728 patients and were related to ICU and in-hospital death using logistic regression analysis. Mortality rates and adjusted odds ratios for ICU death per mean absolute glucose change per hour quartile across quartiles of mean glucose were calculated. Patients were treated with a computerized insulin algorithm (target glucose 72–126 mg/dL). Mean age was 65 ± 13 yrs, 34% were female, and 6.3% of patients died in the ICU. The odds ratios for ICU death were higher for quartiles of mean absolute glucose change per hour compared with quartiles of mean glucose or sd. The highest odds ratio for ICU death was found in patients with the highest mean absolute glucose change per hour in the upper glucose quartile: odds ratio 12.4 (95% confidence interval, 3.2–47.9; p < .001). Mortality rates were lowest in the lowest mean absolute glucose change per hour quartiles. Conclusions:High glucose variability is firmly associated with ICU and in-hospital death. High glucose variability combined with high mean glucose values is associated with highest ICU mortality. In patients treated with strict glycemic control, low glucose variability seemed protective, even when mean glucose levels remained elevated.

Glucose variability; does it matter?

Overall lowering of glucose is of pivotal importance in the treatment of diabetes, with proven beneficial effects on microvascular and macrovascular outcomes. Still, patients with similar glycosylated hemoglobin levels and mean glucose values can have markedly different daily glucose excursions. The role of this glucose variability in pathophysiological pathways is the subject of debate. It is strongly related to oxidative stress in in vitro, animal, and human studies in an experimental setting. However, in real-life human studies including type 1 and type 2 diabetes patients, there is neither a reproducible relation with oxidative stress nor a correlation between short-term glucose variability and retinopathy, nephropathy, or neuropathy. On the other hand, there is some evidence that long-term glycemic variability might be related to microvascular complications in type 1 and type 2 diabetes. Regarding mortality, a convincing relationship with short-term glucose variability has only been demonstrated in nondiabetic, critically ill patients. Also, glucose variability may have a role in the prediction of severe hypoglycemia. In this review, we first provide an overview of the various methods to measure glucose variability. Second, we review current literature regarding glucose variability and its relation to oxidative stress, long-term diabetic complications, and hypoglycemia. Finally, we make recommendations on whether and how to target glucose variability, concluding that at present we lack both the compelling evidence and the means to target glucose variability separately from all efforts to lower mean glucose while avoiding hypoglycemia.

The endothelial glycocalyx: a potential barrier between health and vascular disease.

Purpose of review Although cardiovascular prevention has improved substantially, we still face the challenge of finding new targets to reduce the sequelae of atherosclerosis further. In this regard, optimizing the vasculoprotective effects of the vessel wall itself warrants intensive research. In particular, the endothelial glycocalyx, consisting of proteoglycans, glycoproteins and adsorbed plasma proteins, may play an essential role in protecting the vessel wall from atherosclerosis. Recent developments In this review, we will discuss the different vasculoprotective effects exerted by the endothelial glycocalyx, the factors that damage it, and the first preliminary data on the glycocalyx dimension in humans. Whereas most glycocalyx research has traditionally focused on the microvasculature, more recent data have underscored the importance of the glycocalyx in protecting the macrovasculature against pro-atherogenic insults. It has been shown that glycocalyx loss is accompanied by a wide array of unfavourable changes in both small and larger vessels. Pro-atherogenic stimuli increase the shedding of glycocalyx constituents into the circulation, contributing to the progressive loss of the vasculoprotective properties of the vessel wall. Novel techniques have facilitated reproducible measurements of systemic glycocalyx volume in humans. Consistent with experimental data, the volume of the human glycocalyx is also severely perturbed by exposure to atherogenic risk factors. Summary Cumulating evidence suggests that an intact glycocalyx protects the vessel wall, whereas disruption of the glycocalyx upon atherogenic stimuli increases vascular vulnerability for atherogenesis.

Evaluation of short-term consequences of hypoglycemia in an intensive care unit.

Background:Introduction of strict glycemic control has increased the risk for hypoglycemia in the intensive care unit. Little is known about the consequences of hypoglycemia in this setting. We examined short-term consequences (seizures, coma, and death) of hypoglycemia in the intensive care unit. Patients and Methods:All occurrences of hypoglycemia (glucose of <45 mg/dL) in our intensive care unit between September 1, 2002, and September 1, 2004, were identified. Patients with hypoglycemia (n = 156) were matched for time to hypoglycemia with control patients drawn from the at-risk population (nested case control method). Seizures observed within 8 hrs after hypoglycemia were scored. Discharge summaries for cases and controls were reviewed for occurrence of possible hypoglycemia-associated coma and death. A hazard ratio for in-hospital death was calculated with Cox regression analysis. Results:The hazard ratio for in-hospital death was 1.03 (95% confidence interval, 0.68–1.56; p = .88) in patients with a first occurrence of hypoglycemia relative to the controls without hypoglycemia, corrected for duration of intensive care unit admittance before hypoglycemia, age, sex, and Acute Physiology and Chronic Health Evaluation II score at admission. No cases of hypoglycemia-associated death were reported. Hypoglycemic coma was reported in two patients. Seizures after hypoglycemia were observed in one patient. Conclusions:In this study, no association between incidental hypoglycemia and mortality was found. However, this data set is too small to definitely exclude the possibility that hypoglycemia is associated with intensive care unit mortality. In three patients with possible hypoglycemia-associated coma or seizures, a causal role for hypoglycemia seemed likely but could not fully be established.

The therapeutic potential of manipulating gut microbiota in obesity and type 2 diabetes mellitus.

Obesity and type 2 diabetes mellitus (T2DM) are attributed to a combination of genetic susceptibility and lifestyle factors. Their increasing prevalence necessitates further studies on modifiable causative factors and novel treatment options. The gut microbiota has emerged as an important contributor to the obesity—and T2DM—epidemic proposed to act by increasing energy harvest from the diet. Although obesity is associated with substantial changes in the composition and metabolic function of the gut microbiota, the pathophysiological processes remain only partly understood. In this review we will describe the development of the adult human microbiome and discuss how the composition of the gut microbiota changes in response to modulating factors. The influence of short‐chain fatty acids, bile acids, prebiotics, probiotics, antibiotics and microbial transplantation is discussed from studies using animal and human models. Ultimately, we aim to translate these findings into therapeutic pathways for obesity and T2DM in humans.

Impact of oral vancomycin on gut microbiota, bile acid metabolism, and insulin sensitivity

BACKGROUND & AIMS Obesity has been associated with changes in the composition and function of the intestinal microbiota. Modulation of the microbiota by antibiotics also alters bile acid and glucose metabolism in mice. Hence, we hypothesized that short term administration of oral antibiotics in humans would affect fecal microbiota composition and subsequently bile acid and glucose metabolism. METHODS In this single blinded randomized controlled trial, 20 male obese subjects with metabolic syndrome were randomized to 7 days of amoxicillin 500 mg t.i.d. or 7 days of vancomycin 500 mg t.i.d. At baseline and after 1 week of therapy, fecal microbiota composition (Human Intestinal Tract Chip phylogenetic microarray), fecal and plasma bile acid concentrations as well as insulin sensitivity (hyperinsulinemic euglycemic clamp using [6,6-(2)H2]-glucose tracer) were measured. RESULTS Vancomycin reduced fecal microbial diversity with a decrease of gram-positive bacteria (mainly Firmicutes) and a compensatory increase in gram-negative bacteria (mainly Proteobacteria). Concomitantly, vancomycin decreased fecal secondary bile acids with a simultaneous postprandial increase in primary bile acids in plasma (p<0.05). Moreover, changes in fecal bile acid concentrations were predominantly associated with altered Firmicutes. Finally, administration of vancomycin decreased peripheral insulin sensitivity (p<0.05). Amoxicillin did not affect any of these parameters. CONCLUSIONS Oral administration of vancomycin significantly impacts host physiology by decreasing intestinal microbiota diversity, bile acid dehydroxylation and peripheral insulin sensitivity in subjects with metabolic syndrome. These data show that intestinal microbiota, particularly of the Firmicutes phylum contributes to bile acid and glucose metabolism in humans. This trial is registered at the Dutch Trial Register (NTR2566).

Hypoglycemia is associated with intensive care unit mortality.

Objective:The implementation of intensive insulin therapy in the intensive care unit is accompanied by an increase in hypoglycemia. We studied the relation between hypoglycemia on intensive care unit mortality, because the evidence on this subject is conflicting. Design:Retrospective database cohort study. Setting:An 18-bed medical/surgical intensive care unit in a teaching hospital (Onze Lieve Vrouwe Gasthuis Hospital, Amsterdam, The Netherlands). Patients:A total of 5961 patients admitted to from 2004 to 2007 were analyzed. Readmissions and patients with a withholding care policy or with hypoglycemia on the first glucose measurement were excluded. Patients were treated with a computerized insulin algorithm (target glucose range, 72-126 mg/dL). Interventions:None. Measurements and Main Results:All first episodes of hypoglycemia (glucose ≤45 mg/dL) were derived from 154,015 glucose values. Using Poisson regression, the incidence rates for intensive care unit death and incidence rate ratio comparing exposure and nonexposure to hypoglycemia were calculated. Patients were considered to be exposed to hypoglycemia from the event until the end of intensive care unit admittance. We corrected for severity of disease using the daily Sequential Organ Failure Assessment score. Age, sex, cardiothoracic surgery, sepsis, and diabetes mellitus were also included as possible confounders. Two hundred eighty-eight (4.8%) patients experienced at least one episode of hypoglycemia. Median age was 68 yrs (range, 58-75 yrs), 66% were male, and 6.4% died in the intensive care unit. The incidence rate of death in patients exposed to hypoglycemia was 40 per 1000 intensive care unit days compared with 17 per 1000 intensive care unit days in patients without exposure. The adjusted incidence rate ratio for intensive care unit death was 2.1 (95% confidence interval, 1.6-2.8; p < .001). Conclusions:Hypoglycemia is related to intensive care unit mortality, also when adjusted for a daily adjudicated measure of disease severity, indicating the possibility of a causal relationship.

Prevalence of diabetes mellitus and the performance of a risk score among Hindustani Surinamese, African Surinamese and ethnic Dutch: a cross-sectional population-based study

BackgroundWhile the prevalence of type 2 diabetes mellitus (DM) is high, tailored risk scores for screening among South Asian and African origin populations are lacking. The aim of this study was, first, to compare the prevalence of (known and newly detected) DM among Hindustani Surinamese, African Surinamese and ethnic Dutch (Dutch). Second, to develop a new risk score for DM. Third, to evaluate the performance of the risk score and to compare it to criteria derived from current guidelines.MethodsWe conducted a cross-sectional population based study among 336 Hindustani Surinamese, 593 African Surinamese and 486 Dutch, aged 35–60 years, in Amsterdam. Logistic regressing analyses were used to derive a risk score based on non-invasively determined characteristics. The diagnostic accuracy was assessed by the area under the Receiver-Operator Characteristic curve (AUC).ResultsHindustani Surinamese had the highest prevalence of DM, followed by African Surinamese and Dutch: 16.7, 8.1, 4.2% (age 35–44) and 35.0, 19.0, 8.2% (age 45–60), respectively. The risk score included ethnicity, body mass index, waist circumference, resting heart rate, first-degree relative with DM, hypertension and history of cardiovascular disease. Selection based on age alone showed the lowest AUC: between 0.57–0.62. The AUC of our score (0.74–0.80) was higher than that of criteria from guidelines based solely on age and BMI and as high as criteria that required invasive specimen collection.ConclusionIn Hindustani Surinamese and African Surinamese populations, screening for DM should not be limited to those over 45 years, as is advocated in several guidelines. If selective screening is indicated, our ethnicity based risk score performs well as a screening test for DM among these groups, particularly compared to the criteria based on age and/or body mass index derived from current guidelines.

Duplex Doppler measurements of portal venous flow in normal subjects inter-and intra-observer variability

We investigated the variability of quantitative duplex Doppler measurements of portal flow. Measurements were validated in vitro using a flow phantom. The measured flow Q (ml/min), is related to the actual phantom output P (ml/min) according to the following formula: Q = 1.08 (P + 44) (r = 0.998). To estimate inter- and intra-observer variance, 38 subjects without portal hypertension were examined in two groups. Two observers examined the first group of subjects (n = 19), from a routine daily ultrasound schedule. Significant differences were found in mean +/- S.D. portal flow (692 +/- 182 ml/min vs. 613 +/- 185 ml/min, p = 0.04) and mean +/- S.D. velocity (15.3 +/- 3.9 cm/s vs. 13.2 +/- 2.6 cm/s, p = 0.01). The combined inter- and intra-observer coefficient of variation (S.D.) was 24% (158 ml/min), 9% (0.92 mm) and 24% (3.4 cm/s) for portal flow, diameter and velocity respectively. Non-systematic components of variance were the largest. Patient characteristics, age, sex, height, weight and body surface area did not influence measurement variations. In the second group of healthy volunteers (n = 19), where variance in measurements over 3 consecutive days was comparable to the combined variance in the first group, the non-systematic variance component was also the largest. We conclude that quantitative duplex Doppler measurements of portal venous flow are mainly subject to non-systematic variability. A coefficient of variation of 24% can be expected in diagnostic measurements in a single patient. Examination by a single observer is advisable. The value of this technique lies in the analysis of pathophysiological mechanisms in portal flow changes in large groups of subjects.

Insulin Therapy for Type 2 Diabetes

A number of landmark randomized clinical trials established that insulin therapy reduces microvascular complications (1,2). In addition, recent follow-up data from the U.K. Prospective Diabetes Study (UKPDS) suggest that early insulin treatment also lowers macrovascular risk in type 2 diabetes (3). Whereas there is consensus on the need for insulin, controversy exists on how to initiate and intensify insulin therapy. The options for the practical implementation of insulin therapy are many. In this presentation, we will give an overview of the evidence on the various insulin regimens commonly used to treat type 2 diabetes. Secondary analyses of the aforementioned landmark trials endeavored to establish a glycemic threshold value below which no complications would occur. The UKPDS found no evidence for such a threshold for A1C, but instead showed that better glycemic control was associated with reduced risks of complications over the whole glycemic range (“the lower the better”) (4). For the management of type 2 diabetes, this resulted in the recommendation to “maintain glycemic levels as close to the nondiabetic range as possible” (5). However, in contrast to the UKPDS, the Kumamoto study observed a threshold, with no exacerbation of microvascular complications in patients with type 2 diabetes whose A1C was <6.5%, suggesting no additional benefit in lowering A1C below this level (2). Moreover, the intensive glycemia treatment arm of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study, targeting A1C <6.0%, was discontinued because of higher mortality in this group compared with the standard therapy group targeting A1C from 7.0 to 7.9% (6). Therefore, the American Diabetes Association (ADA) recommendation of an A1C target <7.0% seems the most balanced compromise at present (7). Another important conclusion of the UKPDS was that the risk reductions in long-term complications were related to the levels of glycemic control …