Relative roles of insulin and hypoglycaemia on induction of neuroendocrine responses to, symptoms of, and deterioration of cognitive function in hypoglycaemia in male and female humans

α- or β-Adrenergic blockade does not affect transplanted islet cell responses to hypoglycemia in type 1 diabetes

Type 1 diabetes recipients of intrahepatic islet transplantation exhibit glucose-dependent suppression of insulin and activation of glucagon secretion in response to insulin-induced hypoglycemia associated with clinical protection from hypoglycemia. Whether sympathetic activation of adrenergic receptors on transplanted islets is required for these responses in defense against hypoglycemia is not known. To evaluate the adrenergic contribution to posttransplant glucose counterregulation, we performed a randomized, double-blind crossover study of responses during a hyperinsulinemic euglycemic-hypoglycemic clamp under phentolamine (α-adrenergic blockage), propranolol (β-adrenergic blockage), or placebo infusion. Characteristics of participants (5 females/4 males) were as follows: median (range) age 53 (34-63) yr, diabetes duration 29 (18-56) yr, posttransplant 7.0 (1.9-8.4) yr, HbA1c 5.8 (4.5-6.8)%, insulin in-/dependent 5/4, all on tacrolimus-based immunosuppression. During the clamp, blood pressure was lower with phentolamine and heart rate was lower with propranolol versus placebo (P < 0.05). There was no difference in the suppression of endogenous insulin secretion (derived from C-peptide measurements) during the euglycemic or hypoglycemic phases, and although levels of glucagon were similar with phentolamine or propranolol vs. placebo, the increase in glucagon from eu- to hypoglycemia was greater with propranolol vs. placebo (P < 0.05). Pancreatic polypeptide was greater with phentolamine versus placebo during the euglycemic phase (P < 0.05), and free fatty acids were lower and the glucose infusion rate was higher with propranolol versus placebo during the hypoglycemic phase (P < 0.05 for both). These results indicate that neither physiological α- nor β-adrenergic blockade attenuates transplanted islet responses to hypoglycemia, suggesting sympathetic reinnervation of the islet graft is not necessary for posttransplant glucose counterregulation.NEW & NOTEWORTHY Whether adrenergic input to islets is necessary for glucose homeostasis in humans is debated. Here, the adrenergic contribution to intrahepatically transplanted islet cell responses to hypoglycemia in individuals with type 1 diabetes was investigated through α- or β-adrenergic receptor blockade during hyperinsulinemic euglycemic-hypoglycemic clamps. Neither α- nor β-adrenergic blockage affected the suppression of endogenous insulin or activation of glucagon secretion, suggesting that sympathetic reinnervation of islet grafts is not required for posttransplant defense against hypoglycemia.

Approach to the Hypoglycemic Patient

Hypoglycemia is commonly encountered in the emergency department. Patients can present with a myriad of symptoms and its presentation can mimic other more serious diagnoses. Despite the relative ease of its management, clinicians often miss the diagnosis or mismanage it even when discovered. Glucose is an important energy source for the brain and failing to recognize hypoglycemia or mismanaging it can lead to permanent neurologic disability or death. Although it is important to replenish glucose in a rapid fashion, it is equally important to discover and manage the underlying etiology to prevent further episodes of hypoglycemia.

The role of gastric emptying in glucose homeostasis and defense against hypoglycemia: Innocent bystander or partner in crime?

Maintenance of plasma glucose (PG) homeostasis is due to a complex network system. Even a minor fall in PG activates multiple neuroendocrine actions promoting hormonal, metabolic and behavioral responses, which prevent and ultimately recover hypoglycemia, primarily neuroglycopenia. Among these responses, gastric emptying (GE) plays an important role by coordinated mechanisms which regulate transit and absorption of nutrients through the small intestine. A bidirectional relationship between GE and glycemia has been established: GE may explain the up to 30-40 % variance in glycemic response following a carbohydrate-rich meal. In addition, acute and chronic hyperglycemia induce deceleration of GE after meals. Hypoglycemia accelerates GE, but its role in counterregulation has been poorly investigated. The role of GE as a counterregulatory mechanism has been confirmed in pathophysiological conditions, such as gastroparesis or following recurrent hypoglycemia. Therefore, it could represent an "ancestral" mechanism, highly conservative and effective in all individuals, conditions and clinical contexts. Recent guidelines recommend GLP-1 receptor agonists (GLP-1RAs) either as the first injectable therapy for type 2 diabetes mellitus or in combination with insulin. Considering the potential impact on GE, it would be important to study subjects on GLP-1 RAs during hypoglycemia, to establish whether a possible deceleration of GE impairs glucose counterregulation.

Decreased branched-chain amino acids and elevated fatty acids during antecedent hypoglycemia in type 1 diabetes

INTRODUCTION

Hypoglycemia is a major limiting factor in achieving recommended glycemic targets for people with type 1 diabetes. Exposure to recurrent hypoglycemia results in blunted hormonal counter-regulatory and symptomatic responses to hypoglycemia. Limited data on metabolic adaptation to recurrent hypoglycemia are available. This study examined the acute metabolic responses to hypoglycemia and the effect of antecedent hypoglycemia on these responses in type 1 diabetes.

RESEARCH DESIGN AND METHODS

Twenty-one outpatients with type 1 diabetes with normal or impaired awareness of hypoglycemia participated in a study assessing the response to hypoglycemia on 2 consecutive days by a hyperinsulinemic glucose clamp. Participants underwent a period of normoglycemia and a period of hypoglycemia during the hyperinsulinemic glucose clamp. Plasma samples were taken during normoglycemia and at the beginning and the end of the hypoglycemic period. Metabolomic analysis of the plasma samples was conducted using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry.

RESULTS

In total, 68 metabolites were studied. On day 1, concentrations of the branched-chain amino acids, leucine (p=3.8×10-3) and isoleucine (p=2.2×10-3), decreased during hypoglycemia. On day 2, during hypoglycemia, five amino acids (including leucine and isoleucine) significantly decreased, and two fatty acids (tetradecanoic and oleic acids) significantly increased (p<0.05). Although more metabolites responded to hypoglycemia on day 2, the responses of the single metabolites were not statistically significant between the 2 days.

CONCLUSIONS

In individuals with type 1 diabetes, one episode of hypoglycemia decreases leucine and isoleucine concentrations. Antecedent hypoglycemia results in the decrement of five amino acids and increases the concentrations of two fatty acids, suggesting an alteration between the two hypoglycemic episodes, which could indicate a possible adaptation. However, more studies are needed to gain a comprehensive understanding of the consequences of these alterations.

TRIAL REGISTRATION NUMBER

NCT01337362.

Clinical Presentation and Diagnostic Approach to Hypoglycemia in Adults Without Diabetes Mellitus

OBJECTIVE

To review the clinical presentation, causes, and diagnostic approach to spontaneous hypoglycemia in adults without diabetes mellitus.

METHODS

A literature review was performed using the PubMed and Google Scholar databases.

RESULTS

Hypoglycemia is uncommon in people who are not on glucose-lowering medications. Under normal physiologic conditions, multiple neural and hormonal counterregulatory mechanisms prevent the development of abnormally low levels of plasma glucose. If spontaneous hypoglycemia is suspected, the Whipple triad should be used to confirm hypoglycemia before pursuing further diagnostic workup. The Whipple criteria include the following: (1) low levels of plasma glucose, (2) signs or symptoms that would be expected with low levels of plasma glucose, and (3) improvement in those signs or symptoms when the level of plasma glucose increases. Spontaneous hypoglycemia can be caused by conditions that cause endogenous hyperinsulinism, including insulinoma, postbariatric hypoglycemia, and noninsulinoma pancreatogenous hypoglycemia. Spontaneous hypoglycemia can also be seen with critical illness, hepatic or renal dysfunction, hormonal deficiency, non-diabetes-related medications, and non-islet cell tumors. The initial diagnostic approach should begin by obtaining a detailed history of the nature and timing of the patient's symptoms, medications, underlying comorbid conditions, and any acute illness. A laboratory evaluation should be conducted at the time of the spontaneous symptomatic episode. Supervised tests such as a 72-hour fast or mixed-meal test may be needed to recreate the situation under which the patient is likely to experience symptoms.

CONCLUSION

We provide an overview of the physiology of counterregulatory response to hypoglycemia, its causes, and diagnostic approaches to spontaneous hypoglycemia in adults.

Machine learning for non-invasive sensing of hypoglycaemia while driving in people with diabetes

AIM

To develop and evaluate the concept of a non-invasive machine learning (ML) approach for detecting hypoglycaemia based exclusively on combined driving (CAN) and eye tracking (ET) data.

MATERIALS AND METHODS

We first developed and tested our ML approach in pronounced hypoglycaemia, and then we applied it to mild hypoglycaemia to evaluate its early warning potential. For this, we conducted two consecutive, interventional studies in individuals with type 1 diabetes. In study 1 (n = 18), we collected CAN and ET data in a driving simulator during euglycaemia and pronounced hypoglycaemia (blood glucose [BG] 2.0-2.5 mmol L^-1 ). In study 2 (n = 9), we collected CAN and ET data in the same simulator but in euglycaemia and mild hypoglycaemia (BG 3.0-3.5 mmol L^-1 ).

RESULTS

Here, we show that our ML approach detects pronounced and mild hypoglycaemia with high accuracy (area under the receiver operating characteristics curve 0.88 ± 0.10 and 0.83 ± 0.11, respectively).

CONCLUSIONS

Our findings suggest that an ML approach based on CAN and ET data, exclusively, enables detection of hypoglycaemia while driving. This provides a promising concept for alternative and non-invasive detection of hypoglycaemia.

Pathophysiology and management of hypoglycemia in diabetes

In the century since the discovery of insulin, diabetes has changed from an early death sentence to a manageable chronic disease. This change in longevity and duration of diabetes coupled with significant advances in therapeutic options for patients has fundamentally changed the landscape of diabetes management, particularly in patients with type 1 diabetes mellitus. However, hypoglycemia remains a major barrier to achieving optimal glycemic control. Current understanding of the mechanisms of hypoglycemia has expanded to include not only counter-regulatory hormonal responses but also direct changes in brain glucose, fuel sensing, and utilization, as well as changes in neural networks that modulate behavior, mood, and cognition. Different strategies to prevent and treat hypoglycemia have been developed, including educational strategies, new insulin formulations, delivery devices, novel technologies, and pharmacologic targets. This review article will discuss current literature contributing to our understanding of the myriad of factors that lead to the development of clinically meaningful hypoglycemia and review established and novel therapies for the prevention and treatment of hypoglycemia.

Glycaemic thresholds for counterregulatory hormone and symptom responses to hypoglycaemia in people with and without type 1 diabetes: a systematic review

AIM/HYPOTHESIS

The physiological counterregulatory response to hypoglycaemia is reported to be organised hierarchically, with hormone responses usually preceding symptomatic awareness and autonomic responses preceding neuroglycopenic responses. To compare thresholds for activation of these responses more accurately between people with or without type 1 diabetes, we performed a systematic review on stepped hyperinsulinaemic-hypoglycaemic glucose clamps.

METHODS

A literature search in PubMed and EMBASE was conducted. We included articles published between 1980 and 2018 involving hyperinsulinaemic stepped hypoglycaemic glucose clamps among people with or without type 1 diabetes. Key exclusion criteria were as follows: data were previously published; other patient population; a clamp not the primary intervention; and an inadequate clamp description. Glycaemic thresholds for counterregulatory hormone and/or symptom responses to hypoglycaemia were estimated and compared using generalised logrank test for interval-censored data, where the intervals were either extracted directly or calculated from the data provided by the study. A glycaemic threshold was defined as the glucose level at which the response exceeded the 95% CI of the mean baseline measurement or euglycaemic control clamp. Because of the use of interval-censored data, we described thresholds using median and IQR.

RESULTS

A total of 63 articles were included, whereof 37 papers included participants with type 1 diabetes (n=559; 67.4% male sex, aged 32.7±10.2 years, BMI 23.8±1.4 kg/m²) and 51 papers included participants without diabetes (n=733; 72.4% male sex, aged 31.1±9.2 years, BMI 23.6±1.1 kg/m²). Compared with non-diabetic control individuals, in people with type 1 diabetes, the median (IQR) glycaemic thresholds for adrenaline (3.8 [3.2-4.2] vs 3.4 [2.8-3.9 mmol/l]), noradrenaline (3.2 [3.2-3.7] vs 3.0 [2.8-3.1] mmol/l), cortisol (3.5 [3.2-4.2]) vs 2.8 [2.8-3.4] mmol/l) and growth hormone (3.8 [3.3-3.8] vs. 3.2 [3.0-3.3] mmol/l) all occurred at lower glucose levels in people with diabetes than in those without diabetes (all p≤0.01). Similarly, although both autonomic (median [IQR] 3.4 [3.4-3.4] vs 3.0 [2.8-3.4] mmol/l) and neuroglycopenic (median [IQR] 3.4 [2.8-N/A] vs 3.0 [3.0-3.1] mmol/l) symptom responses were elicited at lower glucose levels in people with type 1 diabetes, the thresholds for autonomic and neuroglycopenic symptoms did not differ for each individual subgroup.

CONCLUSIONS/INTERPRETATION

People with type 1 diabetes have glycaemic thresholds for counterregulatory hormone and symptom responses at lower glucose levels than people without diabetes. Autonomic and neuroglycopenic symptoms responses are generated at about similar levels of hypoglycaemia. There was a considerable variation in the methodology of the articles and the high insulin doses in most of the clamps may affect the counterregulatory responses.

FUNDING

This article has received funding from the Innovative Medicines Initiative 2 Joint Undertaking (JU) under grant agreement no. 777460.

REGISTRATION

This systematic review is registered in PROSPERO (CRD42019120083).

A distinct hypothalamus-to-β cell circuit modulates insulin secretion

The central nervous system has long been thought to regulate insulin secretion, an essential process in the maintenance of blood glucose levels. However, the anatomical and functional connections between the brain and insulin-producing pancreatic β cells remain undefined. Here, we describe a functional transneuronal circuit connecting the hypothalamus to β cells in mice. This circuit originates from a subpopulation of oxytocin neurons in the paraventricular hypothalamic nucleus (PVN^OXT), and it reaches the islets of the endocrine pancreas via the sympathetic autonomic branch to innervate β cells. Stimulation of PVN^OXT neurons rapidly suppresses insulin secretion and causes hyperglycemia. Conversely, silencing of these neurons elevates insulin levels by dysregulating neuronal signaling and secretory pathways in β cells and induces hypoglycemia. PVN^OXT neuronal activity is triggered by glucoprivation. Our findings reveal that a subset of PVN^OXT neurons form functional multisynaptic circuits with β cells in mice to regulate insulin secretion, and their function is necessary for the β cell response to hypoglycemia.

Spontaneous and iatrogenic hypoglycemia in cystic fibrosis

Spontaneous episodes of hypoglycemia can occur in people with cystic fibrosis (CF) without diabetes, who are not on glucose lowering medications. Spontaneous hypoglycemia in CF could occur both in the fasting or postprandial state (reactive hypoglycemia). The pathophysiology of fasting hypoglycemia is thought to be related to malnutrition and increased energy expenditure in the setting of inflammation and acute infections. Reactive hypoglycemia is thought to be due to impaired first phase insulin release in response to a glucose load, followed by a delayed and extended second phase insulin secretion; ineffective counterregulatory response to dropping glucose levels may also play a role. The overall prevalence of spontaneous hypoglycemia varies from 7 to 69% as examined with oral glucose tolerance test (OGTT) or with continuous glucose monitoring (CGM) under free living conditions. Spontaneous hypoglycemia in CF is associated with worse lung function, higher hospitalization rates, and worse clinical status. In addition, patients with CF related diabetes on glucose-lowering therapies are at risk for iatrogenic hypoglycemia. In this article, we will review the pathophysiology, prevalence, risk factors, clinical implications, and management of spontaneous and iatrogenic hypoglycemia in patients with CF.

O-GlcNAcylated p53 in the liver modulates hepatic glucose production

p53 regulates several signaling pathways to maintain the metabolic homeostasis of cells and modulates the cellular response to stress. Deficiency or excess of nutrients causes cellular metabolic stress, and we hypothesized that p53 could be linked to glucose maintenance. We show here that upon starvation hepatic p53 is stabilized by O-GlcNAcylation and plays an essential role in the physiological regulation of glucose homeostasis. More specifically, p53 binds to PCK1 promoter and regulates its transcriptional activation, thereby controlling hepatic glucose production. Mice lacking p53 in the liver show a reduced gluconeogenic response during calorie restriction. Glucagon, adrenaline and glucocorticoids augment protein levels of p53, and administration of these hormones to p53 deficient human hepatocytes and to liver-specific p53 deficient mice fails to increase glucose levels. Moreover, insulin decreases p53 levels, and over-expression of p53 impairs insulin sensitivity. Finally, protein levels of p53, as well as genes responsible of O-GlcNAcylation are elevated in the liver of type 2 diabetic patients and positively correlate with glucose and HOMA-IR. Overall these results indicate that the O-GlcNAcylation of p53 plays an unsuspected key role regulating in vivo glucose homeostasis.

Hypoglycemia in cystic fibrosis: Prevalence, impact and treatment

Hypoglycemia is a common and feared complication of insulin therapy. As in type 1 and type 2 diabetes, people with cystic fibrosis related diabetes are also at risk for hypoglycemia related to insulin therapy. Spontaneous hypoglycemia is also common in patients with CF without diabetes, who are not on glucose lowering medications. Spontaneous hypoglycemia in CF may also occur during or after an oral glucose tolerance test. In this review, we will discuss the definition, epidemiology, pathophysiology and impact of hypoglycemia, with a focus on people with cystic fibrosis. We will also review strategies to manage and prevent hypoglycemia.

Experimental Models of Impaired Hypoglycaemia-Associated Counter-Regulation

Impaired awareness of hypoglycaemia (IAH) affects around a quarter of patients with diabetes who receive insulin treatment. This condition is characterised by a progressive reduction in symptomatic and behavioural responses to hypoglycaemia, increasing risk of deeper drops in blood glucose, unconsciousness, and collapse. Thus, patients with IAH experience severe hypoglycaemic episodes more frequently, resulting in significant morbidity and mortality. IAH is thought to develop as a consequence of whole-body adaptations to repeated insulin-induced hypoglycaemia (RH), with widespread deficits in the hypoglycaemia counter-regulatory response (CRR). Despite this important insight, the precise pathophysiology by which RH leads to an attenuated CRR is unknown. Studies into the underlying mechanisms of IAH have employed a variety of protocols in humans and experimental species. The use of animal models has many investigational benefits, including the unprecedented increase in the availability of transgenic strains. However, modelling impaired hypoglycaemia-associated counter-regulation remains challenging and appropriate interpretation of findings across species and protocols even more so. Here, we review the experimental modelling of IAH and impaired hypoglycaemia-associated counter-regulation, with a focus on understanding species-specific variation in glucose homeostasis. This review will aid investigators in interpreting outputs from different studies in IAH and aid progress in the field.

Diabetes Management Experience and the State of Hypoglycemia: National Online Survey Study

BACKGROUND

Hypoglycemia, or low blood sugar levels, in people with diabetes can be a serious life-threatening condition, and serious outcomes can be avoided if low levels of blood sugar are proactively detected. Although technologies exist to detect the onset of hypoglycemia, they are invasive or costly or exhibit a high incidence of false alarms. Tremors are commonly reported symptoms of hypoglycemia and may be used to detect hypoglycemic events, yet their onset is not well researched or understood.

OBJECTIVE

This study aimed to understand diabetic patients' perceptions of hypoglycemic tremors, as well as their user experiences with technology to manage diabetes, and expectations from a self-management tool to ultimately inform the design of a noninvasive and cost-effective technology that detects tremors associated with hypoglycemia.

METHODS

A cross-sectional internet panel survey was administered to adult patients with type 1 diabetes using the Qualtrics platform in May 2019. The questions focused on 3 main constructs: (1) perceived experiences of hypoglycemia, (2) experiences and expectations about a diabetes management device and mobile app, and (3) beliefs and attitudes regarding intention to use a diabetes management device. The analysis in this paper focuses on the first two constructs. Nonparametric tests were used to analyze the Likert scale data, with a Mann-Whitney U test, Kruskal-Wallis test, and Games-Howell post hoc test as applicable, for subgroup comparisons to highlight differences in perceived frequency, severity, and noticeability of hypoglycemic tremors across age, gender, years living with diabetes, and physical activity.

RESULTS

Data from 212 respondents (129 [60.8%] females) revealed statistically significant differences in perceived noticeability of tremors by gender, whereby males noticed their tremors more (P<.001), and age, with the older population reporting lower noticeability than the young and middle age groups (P<.001). Individuals living longer with diabetes noticed their tremors significantly less than those with diabetes for ≤1 year but not in terms of frequency or severity. Additionally, the majority of our participants (150/212, 70.7%) reported experience with diabetes-monitoring devices.

CONCLUSIONS

Our findings support the need for cost-efficient and noninvasive continuous monitoring technologies. Although hypoglycemic tremors were perceived to occur frequently, such tremors were not found to be severe compared with other symptoms such as sweating, which was the highest rated symptom in our study. Using a combination of tremor and galvanic skin response sensors may show promise in detecting the onset of hypoglycemic events.

Hypoglycemic thalamic activation in type 1 diabetes is associated with preserved symptoms despite reduced epinephrine

Brain responses to low plasma glucose may be key to understanding the behaviors that prevent severe hypoglycemia in type 1 diabetes. This study investigated the impact of long duration, hypoglycemia aware type 1 diabetes on cerebral blood flow responses to hypoglycemia. Three-dimensional pseudo-continuous arterial spin labeling magnetic resonance imaging was performed in 15 individuals with type 1 diabetes and 15 non-diabetic controls during a two-step hyperinsulinemic glucose clamp. Symptom, hormone, global cerebral blood flow and regional cerebral blood flow responses to hypoglycemia were measured. Epinephrine release during hypoglycemia was attenuated in type 1 diabetes, but symptom score rose comparably in both groups. A rise in global cerebral blood flow did not differ between groups. Regional cerebral blood flow increased in the thalamus and fell in the hippocampus and temporal cortex in both groups. Type 1 diabetes demonstrated lesser anterior cingulate cortex activation; however, this difference did not survive correction for multiple comparisons. Thalamic cerebral blood flow change correlated with autonomic symptoms, and anterior cingulate cortex cerebral blood flow change correlated with epinephrine response across groups. The thalamus may thus be involved in symptom responses to hypoglycemia, independent of epinephrine action, while anterior cingulate cortex activation may be linked to counterregulation. Activation of these regions may have a role in hypoglycemia awareness and avoidance of problematic hypoglycemia.

Effect of Dietary Macronutrients on Postprandial Glucagon and Insulin Release in Obese and Normal-Weight Women

The aim of the study was to assess the effect of dietary macronutrients on circulating glucagon and insulin levels in obese and normal-weight women. Potentially, the impaired release of glucagon may proceed abnormal glucose metabolism in obese patients ahead of overt diabetes. In 20 insulin-sensitive women (11 obese and 9 normal-weight), plasma concentrations of insulin and glucagon levels were assessed before and after 3 different macronutrient test meals. AUC_total insulin in the obese group was increased after protein and carbohydrates compared to fatty test meal consumption (3981 ± 2171 and 4869 ± 2784 vs. 2349 ± 1004 μIU∗h/m, p < 0.05, respectively), but without a difference between protein and carbohydrates ingestion. However, in the normal-weight group, AUC_total insulin was increased after carbohydrates compared to fatty test meal ingestion (3929 ± 1719 vs. 2231 ± 509 μIU∗h/ml, p < 0.05) and similar after carbohydrate and protein as well as after fatty and protein test meals (3929 ± 1719 vs. 2231 ± 509 vs. 3046 ± 1406 μIU∗h/ml, respectively). However, AUC_total insulin was significantly increased in obese compared to normal-weight women only after carbohydrate test meal ingestion (4869 ± 2784 vs. 3929 ± 1719 μIU∗h/ml, p < 0.05). AUC_total glucagon was similar after carbohydrate, protein, and fatty test meals ingestion in obese and normal-weight women (921 ± 356 vs. 957 ± 368 vs. 926 ± 262 ng∗h/ml and 1196 ± 14 vs. 1360 ± 662 vs. 1792 ± 1176 ng∗h/ml, respectively). AUC_total glucagon was significantly lower in obese than normal-weight women after a fatty meal (926 ± 262 vs. 1792 ± 1176 ng∗h/ml, p < 0.01). Postprandial glucagon secretion is not related to the macronutrient composition of the meal in normal-weight women since postprandial glucagon concentrations were stable and did not change after carbohydrate, protein, and fatty test meals. Lower glucagon secretion was observed in obese subjects after fatty meal consumption when compared to normal-weight subjects. Postprandial insulin profile was significantly higher after carbohydrate than fatty test meal intake in the obese group and did not differ between obese and normal-weight groups after carbohydrate, protein, and fatty test meals consumption. Impaired glucagon secretion after fatty meat suggests early pancreatic alpha-cell dysfunction, after a carbohydrate meal is a compensatory mechanism.

Impaired Cortisol and Growth Hormone Counterregulatory Responses among Severe Hypoglycemic Patients with Type 2 Diabetes Mellitus

BACKGROUND

Elevated levels of cortisol and growth hormone are critical counterregulatory responses to severe hypoglycemia. However, the proportion and clinical characteristics of patients with type 2 diabetes mellitus (DM) who fail to show appropriate cortisol and/or growth hormone secretion in response to severe hypoglycemia have not been investigated.

METHODS

We measured plasma cortisol and growth hormone levels in type 2 DM patients with severe hypoglycemia who visited the emergency department between 2006 and 2015.

RESULTS

Of 112 hypoglycemic patients, 23 (20.5%) had an impaired cortisol response (<18 μg/dL) and 82 patients (73.2%) had an impaired growth hormone response (<5 ng/mL). Nineteen patients (17.0%) had impaired responses to both cortisol and growth hormone. The patients with impaired responses of cortisol, growth hormone, and both hormones were significantly older and more likely to be female, and had higher admission rates, lower growth hormone levels, and lower adrenocorticotropic hormone levels than the patients with a normal hormonal response. Multivariate logistic regression analysis indicated that an impaired growth hormone response was significantly associated with advanced age, shorter DM duration, a higher admission rate, and a higher body mass index (BMI). An impaired cortisol response was significantly associated with growth hormone levels. Patients with an impaired growth hormone response had higher admission rates than patients with a normal response.

CONCLUSION

A considerable number of type 2 DM patients had impaired cortisol and/or growth hormone responses to severe hypoglycemia. Advanced age, shorter DM duration, and higher BMI were independently associated with an abnormal growth hormone response.

Central Mechanisms of Glucose Sensing and Counterregulation in Defense of Hypoglycemia

Glucose homeostasis requires an organism to rapidly respond to changes in plasma glucose concentrations. Iatrogenic hypoglycemia as a result of treatment with insulin or sulfonylureas is the most common cause of hypoglycemia in humans and is generally only seen in patients with diabetes who take these medications. The first response to a fall in glucose is the detection of impending hypoglycemia by hypoglycemia-detecting sensors, including glucose-sensing neurons in the hypothalamus and other regions. This detection is then linked to a series of neural and hormonal responses that serve to prevent the fall in blood glucose and restore euglycemia. In this review, we discuss the current state of knowledge about central glucose sensing and how detection of a fall in glucose leads to the stimulation of counterregulatory hormone and behavior responses. We also review how diabetes and recurrent hypoglycemia impact glucose sensing and counterregulation, leading to development of impaired awareness of hypoglycemia in diabetes.

Two days of calorie deprivation impairs high level cognitive processes, mood, and self-reported exertion during aerobic exercise: A randomized double-blind, placebo-controlled study

Military personnel and emergency responders perform cognitively-demanding tasks during periods of sustained physical exertion and limited caloric intake. Cognitive function is preserved during short-term caloric restriction, but it is unclear if preservation extends to combined caloric restriction and physical exertion. According to the "reticular-activating hypofrontality" model, vigorous exertion impairs prefrontal cortex activity and associated functions. This double-blind, placebo-controlled, crossover study examined cognitive function during sustained exertion while volunteers were calorically-deprived. Twenty-three volunteers were calorie-depleted for two days on one occasion and fully-fed on another. They completed intermittent bouts of exercise at 40-65% VO_2peak while prefrontal cortex-dependent tasks of cognitive control, mood, and perceived exertion were assessed. Calorie deprivation impaired accuracy on the task-switching task of set-shifting (p < .01) and decreased sensitivity on the go/no-go task of response inhibition (p < .05). Calorie deprivation did not affect risk taking on the Rogers risk task. During exercise, calorie deprivation, particularly on day 2, increased perceived exertion (p < .05) and impaired mood states of tension, depression, anger, vigor, fatigue, and confusion (all p < .01). Physical exertion during severe calorie deprivation impairs cognitive control, mood, and self-rated exertion. Reallocation of cerebral metabolic resources from the prefrontal cortex to structures supporting movement may explain these deficits.

Hypoglycaemia and gastric emptying

Hypoglycaemia is arguably the most important complication of insulin therapy in type 1 and type 2 diabetes. Counter-regulation of hypoglycaemia is dependent on autonomic function and frequent hypoglycaemia may lead to reductions in both autonomic warning signals and the catecholamine response, the so-called "impaired awareness of hypoglycaemia". It is now appreciated that gastric emptying is a major determinant of the glycaemic response to carbohydrate-containing meals in both health and diabetes, that disordered (especially delayed) gastric emptying occurs frequently in diabetes, and that acute hypoglycaemia accelerates gastric emptying substantially. However, the potential relevance of gastric emptying to the predisposition to, and counter-regulation of, hypoglycaemia has received little attention. In insulin-treated patients, the rate of gastric emptying influences the timing of the postprandial insulin requirement, and gastroparesis is likely to predispose to postprandial hypoglycaemia. Conversely, the marked acceleration of gastric emptying induced by hypoglycaemia probably represents an important counter-regulatory response to increase the rate of carbohydrate absorption. This review summarizes the current knowledge of the inter-relationships between hypoglycaemia and gastric emptying, with a focus on clinical implications.

Impact of Hypoglycemia on Brain Metabolism During Diabetes

Diabetes is a metabolic disease afflicting millions of people worldwide. A substantial fraction of world's total healthcare expenditure is spent on treating diabetes. Hypoglycemia is a serious consequence of anti-diabetic drug therapy, because it induces metabolic alterations in the brain. Metabolic alterations are one of the central mechanisms mediating hypoglycemia-related functional changes in the brain. Acute, chronic, and/or recurrent hypoglycemia modulate multiple metabolic pathways, and exposure to hypoglycemia increases consumption of alternate respiratory substrates such as ketone bodies, glycogen, and monocarboxylates in the brain. The aim of this review is to discuss hypoglycemia-induced metabolic alterations in the brain in glucose counterregulation, uptake, utilization and metabolism, cellular respiration, amino acid and lipid metabolism, and the significance of other sources of energy. The present review summarizes information on hypoglycemia-induced metabolic changes in the brain of diabetic and non-diabetic subjects and the manner in which they may affect brain function.

Indications and complications of inpatient parenteral nutrition prescribed to children in a large tertiary referral hospital

BACKGROUND

Parenteral Nutrition (PN) is prescribed to children with intestinal failure. Although life saving, complications are common. Recommendations for indications and constituents of PN are made in the 2005 guidelines by the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN). The aim of this study was to establish if the indications for prescribing PN in a tertiary children's hospital were appropriate, and to identify complications encountered. Data were compared to those published by the National Confidential Enquiry into patient outcome and death (NCEPOD) carried out in the United Kingdom in 2010.

METHODS

Children and newborns receiving inpatient PN over a 6 months period were entered into the study and data was collected prospectively. The appropriate indications for the use of PN were based on the ESPGHAN guidelines. Recorded complications were divided into metabolic, central venous catheter (CVC) related, hepatobiliary and nutritional.

RESULTS

A total of 303 children (67 newborns) were entered into the study. The main indications for the start of PN were critical illness (66/303), surgery (63/303) and bone marrow transplantation (28/303). The ESPGHAN recommendations were followed in 91.7% (278/303) of cases (95.5% of newborns, 90.7% of children). PN was considered inappropriate in 12/303 patients and equivocal in 13. The mean PN duration was 18 days (1-160) and the incidence of complications correlated to the length of PN prescribed. Metabolic, hepatobiliary and CVC related complications affected 74.6, 24.4, 16.4% of newborns and 76.7, 37.7 and 24.6% of children respectively. In relation to the appropriate indications for the start of PN our results mirrored those reported by the NCEPOD audit (92.4% of newborns and 88.6% children). However, the incidence of metabolic disturbances was higher in our cohort (74.6% vs 30.4% in children, 76.7% vs 14.3% in newborns) but CVC related complications lower amongst our newborns (16,4% vs 25%).

CONCLUSIONS

Although the indications for inpatient PN in children is mostly justified, there is still a proportion who is receiving PN unnecessarily. PN related complications remain common. There is a need for better education amongst health professionals prescribing PN and access to nutritional support teams to reduce unwanted side effects.

Impaired hypoglycaemia awareness in type 1 diabetes: lessons from the lab

Hypoglycaemia remains the most common metabolic adverse effect of insulin and sulfonylurea therapy in diabetes. Repeated exposure to hypoglycaemia leads to a change in the symptom complex that characterises hypoglycaemia, culminating in a clinical phenomenon referred to as impaired awareness of hypoglycaemia (IAH). IAH effects approximately 20-25% of people with type 1 diabetes and increases the risk of severe hypoglycaemia. This review focuses on the mechanisms that are responsible for the much higher frequency of hypoglycaemia in people with diabetes compared with those without, and subsequently how repeated exposure to hypoglycaemia leads to the development of IAH. The mechanisms that result in IAH development are incompletely understood and likely to reflect changes in multiple aspects of the counterregulatory response to hypoglycaemia, from adaptations within glucose and non-glucose-sensing cells to changes in the integrative networks that govern glucose homeostasis. Finally, we propose that the general process that incorporates many of these changes and results in IAH following recurrent hypoglycaemia is a form of adaptive memory called 'habituation'.

Acidosis mediates recurrent hypoglycemia-induced increase in ischemic brain injury in treated diabetic rats

OBJECTIVES

Cerebral ischemia is a serious possible manifestation of diabetic vascular disease. Recurrent hypoglycemia (RH) enhances ischemic brain injury in insulin-treated diabetic (ITD) rats. In the present study, we determined the role of ischemic acidosis in enhanced ischemic brain damage in RH-exposed ITD rats.

METHODS

Diabetic rats were treated with insulin and mild/moderate RH was induced for 5 days. Three sets of experiments were performed. The first set evaluated the effects of RH exposure on global cerebral ischemia-induced acidosis in ITD rats. The second set evaluated the effect of an alkalizing agent (Tris-(hydroxymethyl)-aminomethane: THAM) on ischemic acidosis-induced brain injury in RH-exposed ITD rats. The third experiment evaluated the effect of the glucose transporter (GLUT) inhibitor on ischemic acidosis-induced brain injury in RH-exposed ITD rats. Hippocampal pH and lactate were measured during ischemia and early reperfusion for all three experiments. Neuronal survival in Cornu Ammonis 1 (CA1) hippocampus served as a measure of ischemic brain injury.

FINDINGS

Prior RH exposure increases lactate concentration and decreases pH during ischemia and early reperfusion when compared to controls. THAM and GLUT inhibitor treatments attenuated RH-induced increase in ischemic acidosis. GLUT inhibitor treatment reduced the RH-induced increase in lactate levels. Both THAM and GLUT inhibitor treatments significantly decreased ischemic damage in RH-exposed ITD rats.

CONCLUSIONS

Ischemia causes increased acidosis in RH-exposed ITD rats via a GLUT-sensitive mechanism. Exploring downstream pathways may help understand mechanisms by which prior exposure to RH increases cerebral ischemic damage.

Carbohydrates for Soccer: A Focus on Skilled Actions and Half-Time Practices

Carbohydrate consumption is synonymous with soccer performance due to the established effects on endogenous energy store preservation, and physical capacity maintenance. For performance-enhancement purposes, exogenous energy consumption (in the form of drinks, bars, gels and snacks) is recommended on match-day; specifically, before and during match-play. Akin to the demands of soccer, limited opportunities exist to consume carbohydrates outside of scheduled breaks in competition, such as at half-time. The link between cognitive function and blood glucose availability suggests that carbohydrates may influence decision-making and technical proficiency (e.g., soccer skills). However, relatively few reviews have focused on technical, as opposed to physical, performance while also addressing the practicalities associated with carbohydrate consumption when limited in-play feeding opportunities exist. Transient physiological responses associated with reductions in activity prevalent in scheduled intra-match breaks (e.g., half-time) likely have important consequences for practitioners aiming to optimize match-day performance. Accordingly, this review evaluated novel developments in soccer literature regarding (1) the ergogenic properties of carbohydrates for skill performance; and (2) novel considerations concerning exogenous energy provision during half-time. Recommendations are made to modify half-time practices in an aim to enhance subsequent performance. Viable future research opportunities exist regarding a deeper insight into carbohydrate provision on match-day.

Cognitive, neurophysiologic and metabolic sequelae of previous hypoglycemic coma revealed by hyperinsulinemic-hypoglycemic clamp in type 1 diabetic patients

To examine the relationship between electroencephalographic (EEG) activity and hypoglycemia unawareness, we investigated early parameters of vigilance and awareness of various symptom categories in response to hypoglycemia in intensively treated type 1 diabetic (T1DM) patients with different degrees of hypoglycemia unawareness. Hypoglycemia was induced with a hyperinsulinemic-hypoglycemic clamp in six T1DM patients with a history of hypoglycemia unawareness previous severe hypoglycemic coma (SH) and in six T1DM patients without (C) history of hypoglycemia unawareness previous severe hypoglycemic coma. Cognitive function tests (four choice reaction time), counterregulatory responses (adrenaline), and symptomatic responses were evaluated at euglycemia (90 mg/dl) and during step-wise plasma glucose reduction (68, 58 and 49 mg/dl). EEG activity was recorded continuously throughout the study and analyzed by spectral analysis. Cognitive function deteriorated significantly at a glucose threshold of 55 ± 1 mg/dl in both groups (p = ns) during hypoglycemia, while the glucose threshold for autonomic symptoms was significantly lower in SH patients than in C patients (49 ± 1 vs. 54 ± 1 mg/dl, p < 0.05, respectively). In SH patients, eye-closed resting EEG showed a correlation between the mean dominance frequency and plasma glucose (r = 0.62, p < 0.001). Theta relative power increased during controlled hypoglycemia compared to euglycemia (21.6 ± 6 vs. 15.5 ± 3% Hz p < 0.05) and was higher than in the C group (21.6 ± 6 vs. 13.8 ± 3%, p < 0.03). The cognitive task beta activity was lower in the SH group than in the C group (14.8 ± 3 Hz, vs. 22.6 ± 4 vs. p < 0.03). Controlled hypoglycemia elicits cognitive dysfunction in both C and SH patients; however, significant EEG alterations during hypoglycemia were detected mainly in patients with a history of hypoglycemia unawareness and previous severe hypoglycemic coma. These data suggest that prior episodes of hypoglycemic coma modulate brain electric activity.

Relationship between Glycemic Levels and Treatment Outcome among Critically Ill Children admitted into Emergency Room in Enugu

Background

Critically ill children are those in need of immediate attention on arrival to an emergency room. The importance of glycemic level measurement as well as maintaining the patency of the airway, effective breathing and circulation cannot be overemphasied. It has been highlighted that the peak hyperglycemia and hypoglycemia predict poor prognosis, longer lengths of hospital stay and higher mortality. The study aims to assess the relationship between glycemic level and treatment outcomes as well as length of hospital stay.

Methods

Analytical cross sectional method was used to study critically ill children aged ≥1 month to ≤10 years admitted into the Children Emergency Room of Enugu State University Teaching Hospital, Enugu. Their admission blood glucose was done. Interviewer administered questionnaire was used to collect information including sociodemographics, duration of hospitalization and outcome of treatment. Data was analysed using SPSS version 20. Chi square, logistic regressions and Kruskal Wallis tests were done as appropriate.

Results

A total of 300 patients were recruited. One hundred and seventeen (39%) had hyperglycemia, 62 (20.7%) patients had hypoglycaemia and 121 (40.3%) had euglycemia. Two hundred and fifty two (84%) were discharged while 48 (16%) died. There was significant association between glycemic levels and treatment outcome (p = < 0.001). Among the 48 who died, 12 (25.0%) had euglycemia, 21 (43.75%) had hypoglycaemia while 15 (31.25%) had hyperglycemia. On multivariate analysis, there was statistically significant association between hypoglycaemia and mortality (p = < 0.001). Unadjusted, those children with hypoglycaemia at presentation were about 4.7 times (UOR = 0.21, 95% Cl: 0.08–0.38) and adjusted, about 5 times (AOR = 0.20, 95% CI: 0.09–0.47) less likely to survive compared with those with euglycemia. Although not statistically significant, those with hyperglycemia were about 1.3 times less likely to survive compared with euglycemic children, adjusted and unadjusted (UOR = 0.75, 95% Cl: 0.33–1.68).

Conclusion

While both hypo- and hyperglycemia are associated with mortality, hypoglycaemia had a greater effect than hyperglycemia. Glycemic levels significantly affects treatment outcome.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-017-0879-8) contains supplementary material, which is available to authorized users.

Evaluation of a Predictive Low-Glucose Management System In-Clinic

BACKGROUND

Predictions based on continuous glucose monitoring (CGM) data are the basis for automatic suspension and resumption of insulin delivery by a predictive low-glucose management feature termed "suspend before low," which is part of the Medtronic MiniMed^® 640G combined insulin pump and CGM system. This study assessed the safety and performance characteristics of the system in an in-clinic setting at eight sites.

MATERIALS AND METHODS

In-clinic standardized increases in basal insulin delivery rates were used to induce nocturnal hypoglycemia in subjects (14-75 years) with type 1 diabetes wearing the MiniMed 640G system. The "suspend before low" feature was set at 65 mg/dL, and as a result, the predictive algorithm suspended insulin delivery when the forecasted glucose was predicted to be ≤85 mg/dL in 30 min (a 20 mg/dL safety buffer). Reference plasma glucose values (Yellow Springs Instruments [YSI], Yellow Springs, OH) were used to establish hypoglycemia and were defined as ≥2 consecutive values ≤65 mg/dL.

RESULTS

Eighty subjects were screened. Among the 69 successful completers, 27 experienced a hypoglycemic event and 42 did not, a prevention rate of 60%. The mean (±standard deviation) YSI value at the time of pump suspension was 101 ± 18.5 mg/dL, and the mean duration of the 68 "suspend before low" events was 105 ± 27 min. At 120 min after the start of the pump suspension events, the mean YSI value was 102 ± 34.6 mg/dL.

CONCLUSION

The MiniMed 640G "suspend before low" feature prevented 60% of induced predicted hypoglycemic events without significant rebound hyperglycemia.

Two Days of Calorie Deprivation Induced by Underfeeding and Aerobic Exercise Degrades Mood and Lowers Interstitial Glucose but Does Not Impair Cognitive Function in Young Adults

BACKGROUND

In studies assessing the effects of acute undernutrition on cognitive function, volunteers are sedentary and findings are equivocal, even though glucose concentrations fall substantially. However, military personnel and endurance athletes often are underfed when physical demands, and consequently energy expenditure, are substantial.

OBJECTIVE

The objective of this study was to determine whether 2 d of near-total calorie deprivation combined with aerobic exercise degraded cognitive performance and mood.

METHODS

A double-blind, placebo-controlled, crossover design was used. Twenty-three volunteers [17 men (mean ± SD age: 20.5 ± 0.7 y) and 6 women (mean ± SD age: 23.3 ± 1.4 y); mean ± SD body mass index (in kg/m²): 25 ± 3] participated for 68 h, including a 51-h inpatient phase in a calorie-deprived or fully fed state during which behavioral testing was conducted and interstitial glucose was monitored continuously. Mood and cognitive performance, including psychomotor and visual vigilance, visual match-to-sample, repeated acquisition (motor learning), N-back (working memory), and grammatical reasoning, were repeatedly assessed. During each condition, individual daily energy intake and expenditure were controlled. During calorie deprivation, volunteers consumed 266 ± 61 kcal/d; during full feeding, they consumed 3935 ± 769 kcal/d. Participants engaged in identical exercise sessions for 4 h/d at 40-65% of peak volume of oxygen uptake attained.

RESULTS

Calorie deprivation did not affect any aspect of cognitive performance, but produced robust effects on mood measured by the Profile of Mood States, including increased tension (P < 0.001), fatigue (P < 0.001), and total mood disturbance (from -0.80 ± 5.1 to 20.1 ± 6.1; P < 0.001), and decreased vigor (P = 0.002), as indicated by treatment × trial (time) effects on ANOVA. Interstitial glucose concentrations were lower during calorie deprivation than in the fully fed condition (P = 0.002, treatment × trial interaction) and declined to 61 mg/dL by the end of the treatment condition.

CONCLUSION

In healthy young men and women, 2 d of severe calorie deprivation in combination with substantial aerobic exercise adversely affects multiple aspects of mood, but not cognition, in spite of substantial reductions in interstitial glucose concentrations. This trial was registered at clinicaltrials.gov as NCT01603550.

Sex Differences and Role of Estradiol in Hypoglycemia-Associated Counter-Regulation

Vital nerve cell functions, including maintenance of transmembrane voltage and information transfer, occur at high energy expense. Inadequate provision of the obligate metabolic fuel glucose exposes neurons to risk of dysfunction or injury. Clinical hypoglycemia rarely occurs in nondiabetic individuals but is an unfortunate regular occurrence in patients with type 1 or advanced insulin-treated type 2 diabetes mellitus. Requisite strict glycemic control, involving treatment with insulin, sulfonylureas, or glinides, can cause frequent episodes of iatrogenic hypoglycemia due to defective counter-regulation, including reduced glycemic thresholds and diminished magnitude of motor responses. Multiple components of the body's far-reaching energy balance regulatory network, including the hindbrain dorsal vagal complex, provide dynamic readout of cellular energetic disequilibrium, signals that are utilized by the hypothalamus to shape counterregulatory autonomic, neuroendocrine, and behavioral outflow toward restoration of glucostasis. The ovarian steroid hormone 17β-estradiol acts on central substrates to preserve nerve cell energy stability brain-wide, thereby providing neuroprotection against bio-energetic insults such as neurodegenerative diseases and acute brain ischemia. The current review highlights recent evidence implicating estrogen in gluco-regulation in females by control of hindbrain metabolic sensor screening and signaling of hypoglycemia-associated neuro-energetic instability. It is anticipated that new understanding of the mechanistic basis of how estradiol influences metabolic sensory input from this critical brain locus to discrete downstream regulatory network substrates will likely reveal viable new molecular targets for therapeutic simulation of hormone actions that promote positive neuronal metabolic state during acute and recurring hypoglycemia.

Interstitial glucose concentrations and hypoglycemia during 2 days of caloric deficit and sustained exercise: a double-blind, placebo-controlled trial

Military personnel and some athlete populations endure short-term energy deficits from reduced energy intake and/or increased energy expenditure (EE) that may degrade physical and cognitive performance due to severe hypoglycemia (<3.1 mmol/l). The extent to which energy deficits alter normoglycemia (3.9–7.8 mmol/l) in healthy individuals is not known, since prior studies measured glucose infrequently, not continuously. The purpose of this study was to characterize the glycemic response to acute, severe energy deficit compared with fully fed control condition, using continuous glucose monitoring (CGM). For 2 days during a double-blind, placebo-controlled, crossover study, 23 volunteers (17 men/6 women; age: 21.3 ± 3.0 yr; body mass index: 25 ± 3 kg/m) increased habitual daily EE [2,300 ± 450 kcal/day [means ± SD)] by 1,647 ± 345 kcal/day through prescribed exercise (~3 h/day; 40–65% peak O2 consumption), and consumed diets designed to maintain energy balance (FED) or induce 93% energy deficit (DEF). Interstitial glucose concentrations were measured continuously by CGM (Medtronic Minimed). Interstitial glucose concentrations were 1.0 ± 0.9 mmol/l lower during DEF vs. FED ( P < 0.0001). The percentage of time spent in mild (3.1–3.8 mmol/l) hypoglycemia was higher during DEF compared with FED [mean difference = 20.5%; 95% confidence interval (CI): 13.1%, 27.9%; P = 0.04], while time spent in severe (<3.1 mmol/l) hypoglycemia was not different between interventions (mean difference = 4.6%; 95% CI: −0.6%, 9.8%; P = 0.10). Three of 23 participants spontaneously reported symptoms (e.g., nausea) potentially related to hypoglycemia during DEF, and an additional participant reported symptoms during both interventions. These findings suggest that severe hypoglycemia rarely occurs in healthy individuals enduring severe, short-term energy deficit secondary to heavy exercise and inadequate energy intake.

A Link Between Hypoglycemia and Progression of Atherosclerosis in the Veterans Affairs Diabetes Trial (VADT)

OBJECTIVE

To determine whether a link exists between serious hypoglycemia and progression of atherosclerosis in a substudy of the Veterans Affairs Diabetes Trial (VADT) and to examine whether glycemic control during the VADT modified the association between serious hypoglycemia and coronary artery calcium (CAC) progression.

RESEARCH DESIGN AND METHODS

Serious hypoglycemia was defined as severe episodes with loss of consciousness or requiring assistance or documented glucose <50 mg/dL. Progression of CAC was determined in 197 participants with baseline and follow-up computed tomography scans.

RESULTS

During an average follow-up of 4.5 years between scans, 97 participants reported severe hypoglycemia (n = 23) or glucose <50 mg/dL (n = 74). Serious hypoglycemia occurred more frequently in the intensive therapy group than in the standard treatment group (74% vs. 21%, P < 0.01). Serious hypoglycemia was not associated with progression of CAC in the entire cohort, but the interaction between serious hypoglycemia and treatment was significant (P < 0.01). Participants with serious hypoglycemia in the standard therapy group, but not in the intensive therapy group, had ∼50% greater progression of CAC than those without serious hypoglycemia (median 11.15 vs. 5.4 mm(3), P = 0.02). Adjustment for all baseline differences, including CAC, or time-varying risk factors during the trial, did not change the results. Examining the effect of serious hypoglycemia by on-trial HbA1c levels (cutoff 7.5%) yielded similar results. In addition, a dose-response relationship was found between serious hypoglycemia and CAC progression in the standard therapy group only.

CONCLUSIONS

Despite a higher frequency of serious hypoglycemia in the intensive therapy group, serious hypoglycemia was associated with progression of CAC in only the standard therapy group.

Deciphering the Hypoglycemic Glucagon Response: Development of a Graded Hyperinsulinemic Hypoglycemic Clamp Technique in Female Mice

Glucose lowering therapy in type 1 and type 2 diabetes is often associated with hypoglycemic events. To avoid this, glucose lowering therapies need to be developed that support the hypoglycemic defense mechanisms. Such development needs a tool for evaluating counterregulatory mechanisms in vivo. A sustained glucagon release during hypoglycemia is of most importance to hypoglycemic defense mechanisms. We have therefore developed a graded hyperinsulinemic hypoglycemic clamp in mice and used it to evaluate counterregulatory glucagon dynamics. Glucose was clamped at narrow intervals aiming at 2.5, 3.5, 4.5, and 6.0 mmol/L. Glucagon levels were increased during hypoglycemia in a glucose-dependent way with a glucagon counterregulatory threshold between 3.5 and 4.0 mmol/L. Modelling the glucose-glucagon relationship using a hyperbolic curve with the equation: plasma glucagon = -4.20 + 90.79/blood glucose showed high correlation. When comparing this method to the insulin tolerance test as an approach to study glucagon dynamics in vivo, we found that the graded clamp more efficiently evoked a robust, predictable, glucagon response with considerably less variation in blood glucose. In conclusion, we have developed a tool for the study of in vivo glucagon dynamics during hypoglycemia in mice and demonstrated a hyperbolic glucose-counterregulatory glucagon relationship.

Half-time strategies to enhance second-half performance in team-sports players: a review and recommendations

A number of intermittent team sports require that two consecutive periods of play (lasting for ~30-45 min) are separated by a 10-20 min half-time break. The half-time practices employed by team-sports players generally include returning to the changing rooms, temporarily relaxing from the cognitive and physical demands of the first half, rehydration and re-fuelling strategies, addressing injury or equipment concerns, and receiving tactical instruction and coach feedback. However, the typically passive nature of these actions has been associated with physiological changes that impair performance during the second half. Both physical and cognitive performances have been found to decline in the initial stages of subsequent exercise that follows half-time. An increased risk of injury has also been observed during this period. Therefore, half-time provides sports scientists and strength and conditioning coaches with an opportunity to optimise second-half performance. An overview of strategies thought to benefit team-sports athletes is presented; specifically, the efficacy of heat maintenance strategies (including passive and active methods), post-activation potentiation, hormonal priming, and modified hydro-nutritional practices are discussed. A theoretical model of applying these strategies in a manner that compliments current practice is also offered.

Hypoglycemia in everyday life after gastric bypass and duodenal switch

DESIGN

Gastric bypass (GBP) and duodenal switch (DS) in morbid obesity are accompanied by marked metabolic improvements, particularly in glucose control. In recent years, episodes of severe late postprandial hypoglycemia have been increasingly described in GBP patients; data in DS patients are scarce. We recruited three groups of subjects; 15 GBP, 15 DS, and 15 non-operated overweight controls to examine to what extent hypoglycemia occurs in daily life.

METHODS

Continuous glucose monitoring (CGM) was used during 3 days of normal activity. The glycemic variability was measured by mean amplitude of glycemic excursion and continuous overall net glycemic action. Fasting blood samples were drawn, and the patients kept a food and symptom log throughout the study.

RESULTS

The GBP group displayed highly variable CGM curves, and 2.9% of their time was spent in hypoglycemia (<3.3  mmol/l, or 60  mg/dl). The DS group had twice as much time in hypoglycemia (5.9%) and displayed CGM curves with little variation as well as lower HbA1c levels (29.3 vs 35.9 mmol/mol, P<0.05). Out of a total of 72 hypoglycemic episodes registered over the 3-day period, 70 (97%) occurred in the postprandial state and only about one-fifth of the hypoglycemic episodes in the GBP and DS groups were accompanied by symptoms. No hypoglycemias were seen in controls during the 3-day period.

CONCLUSION

Both types of bariatric surgery induce marked, but different, changes in glucose balance accompanied by frequent, but mainly unnoticed, hypoglycemic episodes. The impact and mechanism of hypoglycemic unawareness after weight-reduction surgery deserves to be clarified.

HypoDE: Research Design and Methods of a Randomized Controlled Study Evaluating the Impact of Real-Time CGM Usage on the Frequency of CGM Glucose Values <55 mg/dl in Patients With Type 1 Diabetes and Problematic Hypoglycemia Treated With Multiple Daily Injections

Systems for continuous glucose monitoring (CGM) have been available for a number of years, and numerous clinical studies have been performed with them. Interestingly, in many of these studies patients with an increased risk of hypoglycemic events were excluded. In addition, in most studies subjects were using a pump for insulin delivery. Therefore our knowledge about the benefit of CGM in patients employing multiple daily injections (MDI) of insulin is limited, especially when it comes to a reduction in the risk of low glucose events in high-risk individuals. We are planning to run a 26-week randomized controlled study in Germany (HypoDE, Hypoglycemia in Deutschland) that is focused on evaluating if such a reduction can be observed in patients on MDI with an increased risk of low glucose events. In all, 160 patients will participate in the study, randomized into the intervention group and control group. Ideally one would study if the frequency of severe hypoglycemic events is different between both groups. However, this would require such a large sample size and study duration, so for pragmatic reasons we will use low glucose levels <55 mg/dl (measured by CGM) for at least 20 minutes as a risk marker for severe hypoglycemic events. The results from the HypoDE study shall help determine the advantage of using CGM in subjects with type 1 diabetes with an increased risk of low glucose events treated with MDI.

Non-ICU hospital care of diabetes mellitus in the elderly population

The concept of lower is better when considering the goal for glycemic control in patients with diabetes mellitus has recently been challenged due to recent studies, such as ACCORD, ADVANCE, and VADT, which have observed increased morbidity and mortality from intensive control, especially in older adults, and in those with long duration of diabetes disease and chronic complications. Although evidence in younger patients suggest that blood glucose levels should not be above 180 mg/dl (10.0 mmol/l), there are many unanswered questions and controversies regarding the benefits and risks, methods to achieve and maintain these levels while avoiding hypoglycemia (<70 mg% (3.9 mmol/l)) in the older population. Since the population is aging with a greater life expectancy, it is crucial that these questions be answered. Although several studies of inpatient non-ICU diabetes management have been published, few include older patients. This review will examine available recommendations and explore those controversies regarding non-ICU hospital management in this vulnerable patient population. Additional conditions that impact upon achieving glycemic control will also be discussed. Finally, the older individual has many special needs which may be more important to consider than in young or middle-aged individuals, when transitioning care from in-hospital to home in a patient-centered approach, as recommended by the American Diabetes Association (ADA) and European Society for the Study of Diabetes (EASD).

Prevalence of dysglycemia and association with outcomes in pediatric extracorporeal membrane oxygenation

OBJECTIVES

To evaluate the relationship between glucose derangement, insulin administration, and mortality among children on extracorporeal membrane oxygenation.

DESIGN

Retrospective cohort.

SETTING

Tertiary PICU.

PATIENTS

Two hundred nine children receiving extracorporeal membrane oxygenation, including 97 neonates.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Hyperglycemia and severe hyperglycemia were defined as a single blood glucose level greater than 15 mmol/L (270 mg/dL) and greater than 20 mmol/L (360 mg/dL), respectively. Hypoglycemia and severe hypoglycemia were defined as any single glucose level less than 3.3 mmol/L (60 mg/dL) and less than 2.2 mmol/L (40 mg/dL), respectively. A total of 15,912 glucose values were recorded. The median number of glucose values was 59 per patient, corresponding to a mean 0.53 ± 0.12 tests per hour. Sixty-nine patients (33.0%) without dysglycemia and who received no insulin were defined as the control group. Eighty-nine (42.6%) and 26 (12.4%) patients developed hyperglycemia and severe hyperglycemia, respectively. Sixty-three (30.1%) and 17 (8.1%) patients developed hypoglycemia and severe hypoglycemia, respectively. Sixty-one patients (29.2%) received IV insulin during extracorporeal membrane oxygenation. Both hyperglycemia and hypoglycemia were associated with increased mortality on extracorporeal membrane oxygenation (46% and 48%, respectively, vs 29% of controls; p = 0.03). However, after adjusting for severity of illness and extracorporeal membrane oxygenation complications, abnormal glucose levels were not independently related to mortality.

CONCLUSIONS

Dysglycemia in children on extracorporeal membrane oxygenation was common but not independently associated with increased mortality. The optimal glucose range for this high-risk population requires further investigation.

Central nervous insulin administration does not potentiate the acute glucoregulatory impact of concurrent mild hyperinsulinemia

Experiments in rodents suggest that hypothalamic insulin signaling essentially contributes to the acute control of peripheral glucose homeostasis. Against this background, we investigated in healthy humans whether intranasal (IN) insulin, which is known to effectively reach the brain compartment, impacts systemic glucose metabolism. Twenty overnight-fasted healthy, normal-weight men were IN administered 210 and 420 international units [IU] (10 and 20 IU every 15 min) of the insulin analog aspart (ins-asp) and placebo, respectively, during experimental sessions lasting 6 h. The use of ins-asp rather than human insulin enabled us to disentangle exogenous and endogenous insulin kinetics. IN insulin dose-dependently decreased plasma glucose concentrations while reducing C-peptide and attenuating endogenous insulin levels. However, we also observed a slight dose-dependent permeation of ins-asp into the circulation. In control experiments mimicking the systemic but not the central nervous uptake of the IN 210 IU dose via intravenous infusion of ins-asp at a dose of 0.12 IU/kg/24 h (n = 10), we obtained essentially identical effects on fasting plasma glucose concentrations. This pattern indicates that sustained IN insulin administration to the human brain to enhance central nervous insulin signaling does not acutely alter systemic glucose homeostasis beyond effects accounted for by concurrent mild hyperinsulinemia.