Hypoglycemia counterregulation in elderly humans: relationship to glucose levels

Hypoglycemia unawareness in type 1 diabetes suppresses brain responses to hypoglycemia

BACKGROUND

Among nondiabetic individuals, mild glucose decrements alter brain activity in regions linked to reward, motivation, and executive control. Whether these effects differ in type 1 diabetes mellitus (T1DM) patients with and without hypoglycemia awareness remains unclear.

METHODS

Forty-two individuals (13 healthy control [HC] subjects, 16 T1DM individuals with hypoglycemia awareness [T1DM-Aware], and 13 T1DM individuals with hypoglycemia unawareness [T1DM-Unaware]) underwent blood oxygen level-dependent functional MRI brain imaging during a 2-step hyperinsulinemic euglycemic (90 mg/dl)-hypoglycemic (60 mg/dl) clamp for assessment of neural responses to mild hypoglycemia.

RESULTS

Mild hypoglycemia in HC subjects altered activity in the caudate, insula, prefrontal cortex, and angular gyrus, whereas T1DM-Aware subjects showed no caudate and insula changes, but showed altered activation patterns in the prefrontal cortex and angular gyrus. Most strikingly, in direct contrast to HC and T1DM-Aware subjects, T1DM-Unaware subjects failed to show any hypoglycemia-induced changes in brain activity. These findings were also associated with blunted hormonal counterregulatory responses and hypoglycemia symptom scores during mild hypoglycemia.

CONCLUSION

In T1DM, and in particular T1DM-Unaware patients, there is a progressive blunting of brain responses in cortico-striatal and fronto-parietal neurocircuits in response to mild-moderate hypoglycemia. These findings have implications for understanding why individuals with impaired hypoglycemia awareness fail to respond appropriately to falling blood glucose levels.

FUNDING

This study was supported in part by NIH grants R01DK020495, P30 DK045735, K23DK109284, K08AA023545. The Yale Center for Clinical Investigation is supported by an NIH Clinical Translational Science Award (UL1 RR024139).

Trends in the management levels of metabolic risk factors in middle-aged and elderly patients with type 2 diabetes mellitus: The Korean National Health and Nutrition Examination Survey 1998-2014

The present study examined the temporal trends in the management of blood pressure, glucose, and lipid levels among middle-aged and elderly patients with type 2 diabetes using data from the Korean National Health and Nutrition Examination Survey (1998–2014). A total of 3,689 patients with diabetes were included and divided into middle-aged (30–64 years old) and elderly (≥65 years old) groups. Demographic and lifestyle data were obtained using a self-reported questionnaire, and trained medical staff obtained fasting blood samples and blood pressure data. Laboratory testing was performed to determine blood glucose, cholesterol, and triglyceride levels. In the multivariable adjusted models, significant decreasing trends in the prevalences of hyperglycemia and hypertension were observed in both age groups during 1998–2014, although no trends were observed for lipid levels. Based on the most recent survey, approximately 50% of patients with diabetes had hyperglycemia, and one-third of patients with diabetes and hypertension did not appropriately manage their blood pressure. In addition, 50% of the patients in both age groups did not manage their lipid profiles, and the management of lipid profiles did not improve in recent years. These results suggest that continuous follow-up is needed to effectively manage metabolic risk factors, especially lipid profiles, among patients with diabetes.

Development and Validation of a Questionnaire Evaluating Impaired Hypoglycemia Awareness among Adult Filipino Patients with Type 2 Diabetes Mellitus

Introduction

Hazards of hypoglycemia include accidents, cardiovascular events, neurologic damage, and impaired hypoglycemia awareness (IHA) which presents as inability to perceive and respond to hypoglycemic warning symptoms.

Objective

This study aimed to develop the first questionnaire evaluating IHA adapted from Clarke Hypoglycemia Index (CHI) and validated among adult Filipino patients with Type 2 Diabetes Mellitus (T2DM).

Methodology

A questionnaire development study was conducted involving CHI linguistic translation, its modification through literature review and focus group discussions, panel synthesis, and content validity. A cross-sectional analytic study followed by administration of the questionnaire to 117 adult Filipinos with T2DM, advanced age, long-standing T2DM, insulin or sulfonylurea, polypharmacy, comorbidities and/or prior hypoglycemia. There were 9 participants in pilot testing, 69 in criterion validity against continuous glucose monitoring (CGM), and 108 in construct validity.

Results

IHA domains in the concept map included Elusive Euglycemia Model, Developmental Model, and Cognitive Model. The Filipino-CHI formulated had 8 questions with content validity scores ranging from 87.5-93.75%. Owing to brevity, its internal consistency Cronbach's alpha was 0.45. Criterion validity against CGM yielded 21 patients with biochemical hypoglycemic events, of which 2 had clinical hypoglycemic events and 19 were positive monitor-identified IHA. A questionnaire IHA cutoff score of ≥4 had sensitivity of 89.47%, and area under the curve of 0.55.

Conclusion

An 8-item questionnaire evaluating IHA among adult Filipino T2DM patients was developed and validated.

Exaggerated glucagon responses to hypoglycemia in women with polycystic ovary syndrome

CONTEXT

Premenopausal women have blunted counter-regulatory hormone responses (CRR) to hypoglycemia compared to men. Postmenopausal women have CRR similar to men; the premenopausal pattern can be restored by estrogen. However, glucagon and pancreatic polypeptide (PP) responses remain lower in postmenopausal women than in men. Since hyperandrogenemia contributes to the metabolic phenotype of polycystic ovary syndrome (PCOS), we hypothesize that CRR to hypoglycemia especially of glucagon and PP is exaggerated in premenopausal women with PCOS compared to premenopausal control women.

STUDY SUBJECTS AND METHODS

Ten obese women with PCOS and 9 control women of similar ethnicity, age and BMI underwent determination of CRR in response to hypoglycemia during 180-min 60mU/m²/min insulin dose hypoglycemic clamp with isotopic assessment of endogenous glucose production (EGP). To assess CRR to hypoglycemia, glucagon, cortisol, growth hormone (GH), epinephrine, norepinephrine, PP, lactate, free fatty acid (FFA), β-hydroxybutyrate, and glycerol levels were sampled at 15-min intervals throughout the clamp.

MAIN FINDINGS

Incremental glucagon levels were ~3-fold higher during hypoglycemia (P=0.03) in PCOS. Postabsorptive, steady-state and incremental GH, cortisol, epinephrine, norepinephrine, PP, FFA, glycerol and β-hydroxybutyrate did not differ. At target glucose levels of ~52mg/dL, insulin mediated glucose disposal (IMGD) was decreased by ~40% (P=0.02) in PCOS, compared to control women, despite ~20% higher steady-state insulin levels (P=0.03). Neither postabsorptive nor steady-state EGP differed. However, postabsorptive lactate levels were ~50% higher (P=0.02). PCOS status (P=0.04) and IMGD (P=0.02) predicted the differential glucagon response to hypoglycemia in separate regression models, however, neither parameter remained an independent predictor in a combined model.

PRINCIPAL CONCLUSIONS

Glucagon responses were increased in PCOS, whereas other CRR did not differ. Women with PCOS were insulin resistant under hypoglycemic conditions and higher postabsorptive lactate levels in PCOS were consistent with this finding. Insulin resistance may have contributed to exaggerated glucagon response to hypoglycemia in PCOS.

Management of Hypoglycemia in Nondiabetic Palliative Care Patients: A Prognosis-Based Approach

Hypoglycemia due to underlying terminal illness in nondiabetic end-of-life patients receiving palliative care has not been fully studied. For example, we do not have adequate information on the frequency of spontaneous hypoglycemia in patients as occurs during the different stages of palliative care. Depending on the case-mix nature of the palliative care ward, at least 2% of palliative care patients may develop hypoglycemia near the end of life when the remaining life expectancy counts down in days. As many as 25%-60% of these patients will neither have autonomic response nor have neuroglycopenic symptoms during a hypoglycemic episode. Although it is not difficult to diagnose and confirm a true hypoglycemia when it is suspected clinically, an episode of hypoglycemic attack may go unnoticed in some patients in a hospice setting. Current trends in palliative care focus on providing treatments based on a prognosis-based framework, involving shared decision-making between the patient and caregivers, after considering the prognosis, professional recommendations, patient's autonomy, family expectations, and the current methods for treating the patient's physical symptoms and existential suffering. This paper provides professional care teams with both moral and literature support for providing care to nondiabetic patients presenting with hypoglycemia.

Achieving glycemic control in elderly patients with type 2 diabetes: a critical comparison of current options

The prevalence of type 2 diabetes mellitus (T2DM) is increasing in the elderly. Because of the unique characteristics of elderly people with T2DM, therapeutic strategy and focus should be tailored to suit this population. This article reviews the guidelines and studies related to older people with T2DM worldwide. A few important themes are generalized: 1) the functional and cognitive status is critical for older people with T2DM considering their life expectancy compared to younger counterparts; 2) both severe hypoglycemia and persistent hyperglycemia are deleterious to older adults with T2DM, and both conditions should be avoided when determining therapeutic goals; 3) recently developed guidelines emphasize the avoidance of hypoglycemic episodes in older people, even in the absence of symptoms. In addition, we raise the concern of glycemic variability, and discuss the rationale for the selection of current options in managing this patient population.

Age-dependent and gender-dependent regulation of hypothalamic-adrenocorticotropic-adrenal axis

Tightly regulated output of glucocorticoids is critical to maintaining immune competence, the structure of neurons, muscle, and bone, blood pressure, glucose homeostasis, work capacity, and vitality in the human and experimental animal. Age, sex steroids, gender, stress, body composition, and disease govern glucocorticoid availability through incompletely understood mechanisms. According to an ensemble concept of neuroendocrine regulation, successful stress adaptations require repeated incremental signaling adjustments among hypothalamic corticotropin-releasing hormone and arginine vasopressin, pituitary adrenocorticotropic hormone, and adrenal corticosteroids. Signals are transduced via (positive) feedforward and (negative) feedback effects. Age and gonadal steroids strongly modulate stress-adaptive glucocorticoid secretion by such interlinked pathways.

Hypoglycaemic symptoms and hypoglycaemia threshold in older people with diabetes--a patient perspective

OBJECTIVES

To investigate patients' views about their lowest tolerable blood glucose level and explore symptoms they may develop below that level.

DESIGN

A semi-structured patient interview.

SETTING

Outpatient clinic for older people (≥75 years) with diabetes.

PARTICIPANTS

Patients attending an outpatient clinic over a six months period who are monitoring their blood glucose at home and able to participate in interview.

RESULTS

Sixty one patients gave answers to the interview questions. Mean (SD) age was 82.3 (3.9) years and 33 (54%) were females. All patients indicated that they were usually aware when hypoglycaemia occurs but the symptoms reported were mostly non specific. The threshold for hypoglycaemia was 5 mmol/L in 13 (21%) patients, 6 mmol/L in 14 (23%) patients, 7 mmol/L in 13 (21%) patients, 8 mmol/L in 17 (28%) patients and 9 mmol/L in 4 (7%) patients. There was no significant difference between patients who were symptomatic at a higher blood glucose level (>6 mmo/L) and those who developed symptoms at a lower level (≤6 mmol/L).

CONCLUSION

Older people with diabetes who seem to be aware of hypoglycaemia report mostly non specific symptoms. The threshold of experiencing hypoglycaemic symptoms appears to be higher than the usually defined <4 mmol/L.

Attenuation of age-related declines in glucagon-mediated signal transduction in rat liver by exercise training

This study investigated alterations in glucagon receptor-mediated signal transduction in rat livers from 7- to 25-mo-old animals and examined the effects of exercise training on ameliorating these changes. Sixty-six young (4 mo), middle-aged (12 mo), and old (22 mo) male Fischer 344 rats were divided into sedentary and trained (treadmill running) groups. Isolated hepatic membranes were combined with [(125)I-Tyr(10)]monoiodoglucagon and nine concentrations of glucagon to determine maximal binding capacity (B(max)) and dissociation constant (K(d)). No alterations were found in B(max) among groups; however, middle-aged trained animals had significantly higher glucagon affinity (lower K(d); 21.1 +/- 1.8 nM) than did their untrained counterparts (50.2 +/- 7.1 nM). Second messenger studies were performed by measuring adenylyl cyclase (AC) specific activity under basal conditions and with four pharmacological stimulations to assess changes in receptor-dependent, G protein-dependent, and AC catalyst-dependent cAMP production. Age-related declines were observed in the old animals under all five conditions. Training resulted in increased cAMP production in the old animals when AC was directly stimulated by forskolin. Stimulatory G protein (G(s)) content was reduced with age in the sedentary group; however, training offset this decline. We conclude that age-related declines in glucagon signaling capacity and responsiveness may be attributed, in part, to declines in intrinsic AC activity and changes in G protein [inhibitory G protein (G(i))/G(s)] ratios. These age-related changes occur in the absence of alterations in glucagon receptor content and appear to involve both G protein- and AC-related changes. Endurance training was able to significantly offset these declines through restoration of the G(i)/G(s) ratio and AC activity.