Islet function and stress hyperglycemia: plasma glucose and epinephrine interaction

Challenges in hyperglycemia management in critically ill patients with COVID-19

Hyperglycemia is commonly associated with adverse outcomes especially in patients requiring intensive care unit stay. Data from the corona virus disease 2019 (COVID-19) pandemic indicates that individuals with diabetes appear to be at similar risk for COVID-19 infection to those without diabetes but are more likely to experience increased morbidity and mortality. The proposed hypothesis for hyperglycemia in COVID-19 include insulin resistance, critical illness hyperglycemia (stress- induced hyperglycemia) secondary to high levels of hormones like cortisol and catecholamines that counteract insulin action, acute cytokine storm and pancreatic cell dysfunction. Diabetic patients are more likely to have severe hyperglycemic complications including diabetic ketoacidosis and hyperosmolar hyperglycemic state. Management of hyperglycemia in COVID-19 is often complicated by use of steroids, prolonged total parenteral or enteral nutrition, frequent acute hyperglycemic events, and restrictions with fluid management due to acute respiratory distress syndrome. While managing hyperglycemia special attention should be paid to mode of insulin delivery, frequency of glucose monitoring based on patient and caregiver safety thereby minimizing exposure and conserving personal protective equipment. In this article we describe the pathophysiology of hyperglycemia, challenges encountered in managing hyperglycemia, and review some potential solutions to address them.

Non-ketotic Hyperglycemia Chorea-Ballismus and Intracerebral Hemorrhage: A Case Report and Literature Review

Non-ketotic hyperglycemia chorea-ballismus (NKH-CB) is a rare metabolical syndrome secondary to the hyperglycemic condition, which is characterized by a triad of acute or subacute hemichorea-hemiballismus, hyperglycemic state, and unique abnormalities limited to the striatum on neuroimaging. Several related case studies on this disorder have been reported previously, but NKH-CB had never been associated with intracerebral hemorrhage (ICH). Herein, we report an uncommon case of NKH-CB and ICH that occurred simultaneously in one patient, which provides a challenge for clinicians in making a correct diagnosis. An 88-year-old woman with a long-term history of poor-controlled type 2 diabetes mellitus and hypertension, who presented with a sudden-onset headache, restlessness, severe bilateral choreiform and ballistic movements, elevated levels of glucose and osmolality in the serum, an increased white blood cell count, and two-type hyperdense signs on CT imaging, was finally diagnosed with NKH-CB and ICH. Despite administrated active treatments, the patient's clinical status did not improve and ultimately passed away. This case is reported to remind clinicians to consider the possibility of NKH-CB when patients present sudden-onset choreiform and ballistic movements. It is also the first entity with two-type hyperdense signs on CT imaging simultaneously, which helps us distinguish NKH-CB from ICH more intuitively.

Brain control of blood glucose levels: implications for the pathogenesis of type 2 diabetes

Despite a rapidly growing literature, the role played by the brain in both normal glucose homeostasis and in type 2 diabetes pathogenesis remains poorly understood. In this review, we introduce a framework for understanding the brain's essential role in these processes based on evidence that the brain, like the pancreas, is equipped to sense and respond to changes in the circulating glucose level. Further, we review evidence that glucose sensing by the brain plays a fundamental role in establishing the defended level of blood glucose, and that defects in this control system contribute to type 2 diabetes pathogenesis. We also consider the possibility that the close association between obesity and type 2 diabetes arises from a shared defect in the highly integrated neurocircuitry governing energy homeostasis and glucose homeostasis. Thus, whereas obesity is characterised by an increase in the defended level of the body's fuel stores (e.g. adipose mass), type 2 diabetes is characterised by an increase in the defended level of the body's available fuel (e.g. circulating glucose), with the underlying pathogenesis in each case involving impaired sensing of (or responsiveness to) relevant humoral negative feedback signals. This perspective is strengthened by growing preclinical evidence that in type 2 diabetes the defended level of blood glucose can be restored to normal by therapies that restore the brain's ability to properly sense the circulating glucose level. Graphical abstract.

Role of Insulin in Neurotrauma and Neurodegeneration: A Review

Insulin is a hormone typically associated with pancreatic release and blood sugar regulation. The brain was long thought to be “insulin-independent,” but research has shown that insulin receptors (IR) are expressed on neurons, microglia and astrocytes, among other cells. The effects of insulin on cells within the central nervous system are varied, and can include both metabolic and non-metabolic functions. Emerging data suggests that insulin can improve neuronal survival or recovery after trauma or during neurodegenerative diseases. Further, data suggests a strong anti-inflammatory component of insulin, which may also play a role in both neurotrauma and neurodegeneration. As a result, administration of exogenous insulin, either via systemic or intranasal routes, is an increasing area of focus in research in neurotrauma and neurodegenerative disorders. This review will explore the literature to date on the role of insulin in neurotrauma and neurodegeneration, with a focus on traumatic brain injury (TBI), spinal cord injury (SCI), Alzheimer’s disease (AD) and Parkinson’s disease (PD).

Impact of stress-induced hyperglycemia on the outcome of children with trauma: A cross-sectional analysis based on propensity score-matched population

This was a retrospective study of pediatric trauma patients and were hospitalized in a level-1 trauma center from January 1, 2009 to December 31, 2016. Stress-induced hyperglycemia (SIH) was defined as a hyperglycemia level ≥200 mg/dL upon arrival at the emergency department without any history of diabetes or a hemoglobin A1c level ≥6.5% upon arrival or during the first month of admission. The results demonstrated that the patients with SIH (n = 36) had a significantly longer length of stay (LOS) in hospital (16.4 vs. 7.8 days, p = 0.002), higher rates of intensive care unit (ICU) admission (55.6% vs. 20.9%, p < 0.001), and higher in-hospital mortality rates (5.6% vs. 0.6%, p = 0.028) compared with those with non-diabetic normoglycemia (NDN). However, in the 24-pair well-balanced propensity score-matched patient populations, in which significant difference in sex, age, and injury severity score were eliminated, patient outcomes in terms of LOS in hospital, rate of ICU admission, and in-hospital mortality rate were not significantly different between the patients with SIH and NDN. The different baseline characteristics of the patients, particularly injury severity, may be associated with poorer outcomes in pediatric trauma patients with SIH compared with those with NDN. This study also indicated that, upon major trauma, the response of pediatric patients with SIH is different from that of adult patients.

Focus on FKBP51: A molecular link between stress and metabolic disorders

BACKGROUND

Obesity, Type 2 diabetes (T2D) as well as stress-related disorders are rising public health threats and major burdens for modern society. Chronic stress and depression are highly associated with symptoms of the metabolic syndrome, but the molecular link is still not fully understood. Furthermore, therapies tackling these biological disorders are still lacking. The identification of shared molecular targets underlying both pathophysiologies may lead to the development of new treatments. The FK506 binding protein 51 (FKBP51) has recently been identified as a promising therapeutic target for stress-related psychiatric disorders and obesity-related metabolic outcomes.

SCOPE OF THE REVIEW

The aim of this review is to summarize current evidence of in vitro, preclinical, and human studies on the stress responsive protein FKBP51, focusing on its newly discovered role in metabolism. Also, we highlight the therapeutic potential of FKBP51 as a new treatment target for symptoms of the metabolic syndrome.

MAJOR CONCLUSIONS

We conclude the review by emphasizing missing knowledge gaps that remain and future research opportunities needed to implement FKBP51 as a drug target for stress-related obesity or T2D.

'Beauty and the beast' in infection: How immune-endocrine interactions regulate systemic metabolism in the context of infection

The immune and endocrine systems ensure two vital functions in the body. The immune system protects us from lethal pathogens, whereas the endocrine system ensures proper metabolic function of peripheral organs by regulating systemic homeostasis. These two systems were long thought to operate independently. The immune system uses cytokines and immune receptors, whereas the endocrine system uses hormones to regulate metabolism. However, recent findings show that the immune and endocrine systems closely interact, especially regarding regulation of glucose metabolism. In response to pathogen encounter, cytokines modify responsiveness of peripheral organs to endocrine signals, resulting in altered levels of blood hormones such as insulin, which promotes the ability of the body to fight infection. Here we provide an overview of recent literature describing various mechanisms, which the immune system utilizes to modify endocrine regulation of systemic metabolism. Moreover, we will describe how these immune-endocrine interactions derail in the context of obesity. From a clinical perspective we will elaborate how infection and obesity aggravate the development of metabolic diseases such as diabetes mellitus type 2 in humans. In summary, this review provides a comprehensive overview of immune-induced changes in systemic metabolism following infection, with a focus on regulation of glucose metabolism.

How does homeostasis happen? Integrative physiological, systems biological, and evolutionary perspectives

Homeostasis is a founding principle of integrative physiology. In current systems biology, however, homeostasis seems almost invisible. Is homeostasis a key goal driving body processes, or is it an emergent mechanistic fact? In this perspective piece, I propose that the integrative physiological and systems biological viewpoints about homeostasis reflect different epistemologies, different philosophies of knowledge. Integrative physiology is concept driven. It attempts to explain biological phenomena by continuous formation of theories that experimentation or observation can test. In integrative physiology, "function" refers to goals or purposes. Systems biology is data driven. It explains biological phenomena in terms of "omics"-i.e., genomics, gene expression, epigenomics, proteomics, and metabolomics-it depicts the data in computer models of complex cascades or networks, and it makes predictions from the models. In systems biology, "function" refers more to mechanisms than to goals. The integrative physiologist emphasizes homeostasis of internal variables such as Pco₂ and blood pressure. The systems biologist views these emphases as teleological and unparsimonious in that the "regulated variable" (e.g., arterial Pco₂ and blood pressure) and the "regulator" (e.g., the "carbistat" and "barostat") are unobservable constructs. The integrative physiologist views systems biological explanations as not really explanations but descriptions that cannot account for phenomena we humans believe exist, although they cannot be observed directly, such as feelings and, ultimately, the conscious mind. This essay reviews the history of the two epistemologies, emphasizing autonomic neuroscience. I predict rapprochement of integrative physiology with systems biology. The resolution will avoid teleological purposiveness, transcend pure mechanism, and incorporate adaptiveness in evolution, i.e., "Darwinian medicine."

Homeostatic systems, biocybernetics, and autonomic neuroscience

In this review we describe a series of major concepts introduced during the past 150years that have contributed to our current understanding about how physiological processes required for well-being and survival are regulated. One can theorize that hierarchical networks involving input-output relationships continuously orchestrate and learn adaptive patterns of observable behaviors, cognition, memory, mood, and autonomic systems. Taken together, these networks function as "good regulators" determining levels of internal variables and act as if there were homeostatic comparators ("homeostats"). The consequences of models with vs. without homeostats remain the same in terms of allostatic load and the eventual switch from stabilizing negative feedback loops to destabilizing, pathogenic positive feedback loops. Understanding this switch seems important for comprehending senescence-related, neurodegenerative disorders that involve the autonomic nervous system. Our general proposal is that disintegration of homeostatic systems causes disorders of regulation in degenerative diseases and that medical cybernetics can inspire and rationalize new approaches to treatment and prevention.

The Impact of a Normoglycemic Management Protocol on Clinical Outcomes in the Trauma Intensive Care Unit

BACKGROUND

The purpose of this study was to determine if protocol-driven normoglycemic management in trauma patients affected glucose control, ventilator-associated pneumonia, surgical-site infection, and inpatient mortality.

METHODS

A prospective, consecutive-series, historically controlled study design evaluated protocol-driven normoglycemic management among trauma patients at Vanderbilt University Medical Center. Those mechanically ventilated > or =24 hours and > or =15 years of age were included. A glycemic-control protocol required insulin infusion therapy for glucose >110 mg/dL. Control patients included those who met criteria, were admitted the year preceding protocol implementation, and had hyperglycemia treated at the physician's discretion.

RESULTS

Eight hundred eighteen patients met study criteria; 383 were managed without protocol; 435 underwent protocol. The protocol group had lower glucose levels 7 of 14 days measured. After admission, both groups had mean daily glucose levels <150 mg/dL. No difference in pneumonia (31.6% vs 34.5%; p = .413), surgical infection (5.0% vs 5.7%; p = .645) or mortality (12.3% vs 13.1%; p = .722) occurred between groups. If one episode of blood glucose level was > or =150 mg/dL (n = 638; 78.0%), outcomes were worse: higher daily glucose levels for 14 days after admission (p < .001), pneumonia rates (35.9% vs 23.3%; p = .002), and mortality (14.6% vs 6.1%; p = .002). One or more days of glucose > or =150 mg/dL had a 2- to 3-fold increase in the odds of death. Protocol use in these patients was not associated with outcome improvement.

CONCLUSIONS

Protocol-driven management decreased glucose levels 7 of 14 days after admission without outcome change. One or more glucose levels > or =150 mg/dL were associated with worse outcome.

The predicting ability of serum potassium to assess the duration of mechanical ventilation in critically ill patients

Background:

No previous study has been done to evaluate the admission serum potassium level as a predictor of morbidity or need for mechanical ventilation. The aim of this study is to determine the predictive ability of serum potassium on admission, in critically ill trauma patients, and to evaluate the relation of the potassium level to organ failure, length of stay, ventilator need, and duration of mechanical ventilation.

Materials and Methods:

A prospective, observational study was done on 100 patients >16 years old, admitted to the Medical-Surgical Intensive Care Units (ICU), for over one year. Patients were classified into Group A: Patients who required equal or less than five days of mechanical ventilation and Group B: Patients who required more than five days of mechanical ventilation. The total serum potassium concentrations were measured and the Sequential Organ Failure Assessment (SOFA) score was recorded at the time of admission to the ICU, when connected to the ventilator, and then at the time of weaning from the ventilator.

Results:

There was no significant difference between the Serum K concentrations between the two groups, on admission. However, there were significant difference between the Serum K concentrations at times of receiving and weaning from mechanical ventilation (MV) between the two groups. We found the best cut-off point of 3.45 for serum potassium concentration, to predict the need for longer duration of MV.

Conclusion:

Development of hypokalemia during an ICU stay is associated with the need for mechanical ventilation. Monitoring of the serum potassium levels may be a good prognostic factor for the requirement of mechanical ventilation.

Neuroendocrine circuits governing energy balance and stress regulation: functional overlap and therapeutic implications

Significant comorbidities between obesity-related metabolic disease and stress-related psychological disorders suggest important functional interactions between energy balance and brain stress integration. Largely overlapping neural circuits control these systems, and this anatomical arrangement optimizes opportunities for mutual influence. Here we first review the current literature identifying effects of metabolic neuroendocrine signals on stress regulation, and vice versa. Next, the contributions of reward-driven food intake to these metabolic and stress interactions are discussed. Lastly, we consider the interrelationships between metabolism, stress, and reward in light of their important implications in the development of therapies for metabolism- or stress-related disease.

Risk of cancer in patients using glucose-lowering agents: a nationwide cohort study of 3.6 million people

OBJECTIVES

To study the association between exposures to glucose-lowering therapy and risk of cancer using the nationwide administrative registers in Denmark.

DESIGN

Nationwide cohort study.

SETTING

All hospitals in Denmark.

PARTICIPANTS

All individuals aged ≥35 years in 1998-2009 who were naive to glucose-lowering treatment and had no history of cancer. Primary measures outcomes: first cancer diagnosis between 1998 and 2009. The RR of cancer as dependent on exposure to individual glucose-lowering agents was assessed by multivariable Poisson regression models.

RESULTS

Of 159 894 patients that initiated treatment with glucose-lowering agents, 12 789 developed cancer, incidence rate 17.4/1000 person-years. Of the remaining 3 447 904 individuals not using glucose-lowering agents, 293 878 developed cancer, incidence rate 7.9/1000 person-years. Use of different types of glucose-lowering agents including human insulin, insulin analogues, as well as sulfonylureas were associated with a quantitatively similar and significantly increased RR of cancer of 1.2-1.3 compared with unexposed individuals after multivariable adjustment. For the majority of agents, the authors identified the highest RR of cancer during the first 30 treatment days with a subsequent decline of risk approaching the cancer risk of the background population only 6-12 months after initiation of treatments.

CONCLUSIONS

Use of most glucose-lowering agents including sulfonylureas was associated with a comparable increased risk of cancer shortly after initiation of treatment and subsequently a decline to the risk of the background population. This suggests that the relation is not causal.

Hyperglycemia is a strong prognostic factor of lethality in methanol poisoning

Methanol poisoning is seen in the form of isolated episodes, or intentional ingestion and epidemics. Despite its efficient treatment, methanol poisoning has high morbidity and mortality rates. So far, several studies have been performed to identify the prognostic factors in methanol poisoning. Recently, during the treatment of patients with methanol poisoning, we observed that patients' blood glucose levels were high on presentation to the hospital, particularly in those who expired. Through a literature search, we found that no studies have been performed on blood glucose levels or hyperglycemia in methanol poisoning. Therefore, the present retrospective study was done as a preliminary investigation to understand whether there was a meaningful relationship between methanol poisoning and blood glucose level on presentation, and also if hyperglycemia could be considered as a prognostic factor for mortality. In this retrospective study, a review of the hospital charts was performed for all patients who were treated for methanol poisoning from March 2003 to March 2010 in two hospitals in Tehran, Iran. Those with definitive diagnosis of methanol poisoning, no history of diabetes mellitus, and normal or low body mass index (<25) were included. Patients' demographic information, clinical manifestations, time elapsed between ingestion and presentation, blood glucose level on presentation (before treatment), results of arterial blood gas analysis, and the clinical outcome were recorded. Statistical analysis was done using SPSS software (version 17, Chicago, Illinois, USA) and application of Mann-Whitney U test, Pearson's chi-square test, Pearson correlation coefficient (r), receiver operating characteristic (ROC) curve, and logistic regression. P values less than 0.05 were considered as the statistically significant levels. Ninety-five patients with methanol poisoning met the inclusion criteria and were included in the study. Of these, 91 (96%) were male and 4 (4%) were female. Mean age was 31.61 ± 14.3 years (range, 13 to 75). Among the 95 patients, 68 survived (72%) and 27 expired (28%). Median blood glucose level was 144 mg/dL (range, 75 to 500). There was no significant statistical correlation between blood glucose level and time of treatment, age, pCO(2), or serum bicarbonate concentration, but blood glucose level had a statistically significant correlation with pH (r = -0.242, P = 0.02) and base deficit (r = 0.230, P = 0.03). The mean blood glucose level was 140 ± 55 and 219 ± 99 mg/dL in the survivor and non-survivor patients, respectively (P < 001). Considering the cutoff level of 140 mg/dL for blood glucose and using logistic regression analysis, and adjusting according to the admission data with significant statistical difference in the two study groups, the odds ratio for hyperglycemia as a risk factor for death was 6.5 (95% confidence interval = 1.59-26.4). Our study showed that blood glucose levels were high in methanol poisoning and even higher in those who died in comparison with the survivors. Therefore, hyperglycemia might be a new prognostic factor in methanol poisoning, but further studies are needed to determine whether controlling hyperglycemia has therapeutic consequences.

Hyperinsulinemic-euglycemic clamps in conscious, unrestrained mice

Type 2 diabetes is characterized by a defect in insulin action. The hyperinsulinemic-euglycemic clamp, or insulin clamp, is widely considered the "gold standard" method for assessing insulin action in vivo. During an insulin clamp, hyperinsulinemia is achieved by a constant insulin infusion. Euglycemia is maintained via a concomitant glucose infusion at a variable rate. This variable glucose infusion rate (GIR) is determined by measuring blood glucose at brief intervals throughout the experiment and adjusting the GIR accordingly. The GIR is indicative of whole-body insulin action, as mice with enhanced insulin action require a greater GIR. The insulin clamp can incorporate administration of isotopic 2[¹⁴C]deoxyglucose to assess tissue-specific glucose uptake and [3-³H]glucose to assess the ability of insulin to suppress the rate of endogenous glucose appearance (endoRa), a marker of hepatic glucose production, and to stimulate the rate of whole-body glucose disappearance (Rd).

The miniaturization of the insulin clamp for use in genetic mouse models of metabolic disease has led to significant advances in diabetes research. Methods for performing insulin clamps vary between laboratories. It is important to note that the manner in which an insulin clamp is performed can significantly affect the results obtained. We have published a comprehensive assessment of different approaches to performing insulin clamps in conscious mice¹ as well as an evaluation of the metabolic response of four commonly used inbred mouse strains using various clamp techniques². Here we present a protocol for performing insulin clamps on conscious, unrestrained mice developed by the Vanderbilt Mouse Metabolic Phenotyping Center (MMPC; URL: www.mc.vanderbilt.edu/mmpc). This includes a description of the method for implanting catheters used during the insulin clamp. The protocol employed by the Vanderbilt MMPC utilizes a unique two-catheter system³. One catheter is inserted into the jugular vein for infusions. A second catheter is inserted into the carotid artery, which allows for blood sampling without the need to restrain or handle the mouse. This technique provides a significant advantage to the most common method for obtaining blood samples during insulin clamps which is to sample from the severed tip of the tail. Unlike this latter method, sampling from an arterial catheter is not stressful to the mouse¹. We also describe methods for using isotopic tracer infusions to assess tissue-specific insulin action. We also provide guidelines for the appropriate presentation of results obtained from insulin clamps.

Stress and hormones

In the modern environment one is exposed to various stressful conditions. Stress can lead to changes in the serum level of many hormones including glucocorticoids, catecholamines, growth hormone and prolactin. Some of these changes are necessary for the fight or flight response to protect oneself. Some of these stressful responses can lead to endocrine disorders like Graves' disease, gonadal dysfunction, psychosexual dwarfism and obesity. Stress can also alter the clinical status of many preexisting endocrine disorders such as precipitation of adrenal crisis and thyroid storm.

Increased serum levels of the brain damage marker S100B after apnea in trained breath-hold divers: a study including respiratory and cardiovascular observations

The concentration of the protein S100B in serum is used as a brain damage marker in various conditions. We wanted to investigate whether a voluntary, prolonged apnea in trained breath-hold divers resulted in an increase of S100B in serum. Nine trained breath-hold divers performed a protocol mimicking the procedures they use during breath-hold training and competition, including extensive preapneic hyperventilation and glossopharyngeal insufflation, in order to perform a maximum-duration apnea, i.e., “static apnea” (average: 335 s, range: 281–403 s). Arterial blood samples were collected and cardiovascular variables recorded. Arterial partial pressures of O2 and CO2 (PaO2 and PaCO2) were 128 Torr and 20 Torr, respectively, at the start of apnea. The degree of asphyxia at the end of apnea was considerable, with PaO2 and PaCO2 reaching 28 Torr and 45 Torr, respectively. The concentration of S100B in serum transiently increased from 0.066 μg/l at the start of apnea to 0.083 μg/l after the apnea ( P < 0.05). The increase in S100B is attributed to the asphyxia or to other physiological responses to apnea, for example, increased blood pressure, and probably indicates a temporary opening of the blood-brain barrier. It is not possible to conclude that the observed increase in S100B levels in serum after a maximal-duration apnea reflects a serious injury to the brain, although the results raise concerns considering negative long-term effects. At the least, the results indicate that prolonged, voluntary apnea affects the integrity of the central nervous system and do not preclude cumulative effects.

Sense of coherence buffers relationships of chronic stress with fasting glucose levels

Sense of coherence (SOC) was examined as a buffer of the relationship of chronic stress with fasting glucose and insulin levels. Spouse caregivers of persons with diagnoses of Alzheimer's disease (AD) (n = 73) were compared to controls [spouses of nondemented persons (n = 69)], group-matched on age/gender. After controlling for anger and coronary heart disease (CHD), interactions of SOC and gender explained variance in glucose (but not insulin) at study entry (T1) and 15-18 months later (T2). However, this occurred only in caregivers. At both times SOC and glucose were negatively related in men caregivers but not in women caregivers or in controls. In caregivers (but not controls), SOC at T1 predicted glucose at T2, independent of gender, anger, and glucose at T1; and hassles at T1 appeared to mediate this relationship. Future research should examine SOC as a buffer of other chronic stressors and metabolic variables.