Exercise-related hypoglycemia in diabetes mellitus

Closed-Loop Insulin Delivery for Adults with Type 1 Diabetes Undertaking High-Intensity Interval Exercise Versus Moderate-Intensity Exercise: A Randomized, Crossover Study

BACKGROUND

We aimed to compare closed-loop glucose control for people with type 1 diabetes undertaking high-intensity interval exercise (HIIE) versus moderate-intensity exercise (MIE).

METHODS

Adults with type 1 diabetes established on insulin pumps undertook HIIE and MIE stages in random order during automated insulin delivery via a closed-loop system (Medtronic). Frequent venous sampling for glucose, lactate, ketones, insulin, catecholamines, cortisol, growth hormone, and glucagon levels was performed. The primary outcome was plasma glucose <4.0 mmol/L for ≥15 min, from exercise commencement to 120 min postexercise. Secondary outcomes included continuous glucose monitoring and biochemical parameters.

RESULTS

Twelve adults (age mean ± standard deviation 40 ± 13 years) were recruited; all completed the study. Plasma glucose of one participant fell to 3.4 mmol/L following MIE completion; no glucose levels were <4.0 mmol/L for HIIE (primary outcome). There were no glucose excursions >15.0 mmol/L for either stage. Mean (±standard error) plasma glucose did not differ between stages pre-exercise; was higher during exercise in HIIE than MIE (11.3 ± 0.5 mmol/L vs. 9.7 ± 0.6 mmol/L, respectively; P < 0.001); and remained higher until 60 min postexercise. There were no differences in circulating free insulin before, during, or postexercise. During HIIE compared with MIE, there were greater increases in lactate (P < 0.001), catecholamines (all P < 0.05), and cortisol (P < 0.001). Ketones increased more with HIIE than MIE postexercise (P = 0.031).

CONCLUSIONS

Preliminary findings suggest that closed-loop glucose control is safe for people undertaking HIIE and MIE. However, the management of the postexercise rise in ketones secondary to counter-regulatory hormone-induced insulin resistance observed with HIIE may represent a challenge for closed-loop systems.

Risk of hypoglycaemia in users of sulphonylureas compared with metformin in relation to renal function and sulphonylurea metabolite group: population based cohort study

OBJECTIVE

 To determine the association between use of sulphonylureas and risk of hypoglycaemia in relation to renal function and sulphonylurea metabolic group compared with use of metformin.

DESIGN

 Population based cohort study using routinely collected data from general practices in England.

SETTING

 Clinical Practice Research Datalink (CPRD) database, 2004-12.

PARTICIPANTS

 120 803 new users of a non-insulin antidiabetic agent with at least one prescription and aged 18 years or more. The first prescription defined start of follow-up. Patients were followed until the end of data collection, a record for hypoglycaemia, or a blood glucose level of less than 3.0 mmol/L.

MAIN OUTCOME MEASURES

 Associations between sulphonylurea dose, renal impairment, type of sulphonylurea used, and risk of hypoglycaemia, were determined using Cox proportional hazard models. Adjustments were made for age, sex, lifestyle, comorbidity, and drug use.

RESULTS

 The risk of hypoglycaemia in current users of sulphonylureas only was significantly increased compared with current users of metformin only (adjusted hazard ratio 2.50, 95% confidence interval 2.23 to 2.82). The higher risk in current users of sulphonylureas only was further increased in patients with an estimated glomerular filtration rate of less than 30 mL/min/1.73 m(2) (4.96, 3.76 to 6.55). The risk of hypoglycaemia was also significantly higher in patients with a high sulphonylurea dose (3.12, 2.68 to 3.62) and in current users of glibenclamide (7.48, 4.89 to 11.44). Gliclazide, the sulphonylurea of first choice, showed a similar risk of hypoglycaemia compared with other sulphonylureas.

CONCLUSIONS

 Sulphonylurea treatment in patients with a renal function of less than 30 mL/min/1.73 m(2) should be considered with caution. Moreover, an increased risk of hypoglycaemic events was observed among all users of sulphonylureas. This contrasts with several guidelines that recommend gliclazide as first choice sulphonylurea, and therefore requires further investigation.

Effects of Antecedent GABA A Receptor Activation on Counterregulatory Responses to Exercise in Healthy Man

The aim of this study was to determine whether antecedent stimulation of γ-aminobutyric acid (GABA) A receptors with the benzodiazepine alprazolam can blunt physiologic responses during next-day moderate (90 min) exercise in healthy man. Thirty-one healthy individuals (16 male/15 female aged 28 ± 1 year, BMI 23 ± 3 kg/m(2)) were studied during separate, 2-day protocols. Day 1 consisted of morning and afternoon 2-h hyperinsulinemic-euglycemic or hypoglycemic clamps with or without 1 mg alprazolam given 30 min before a clamp. Day 2 consisted of 90-min euglycemic cycling exercise at 50% VO2max. Despite similar euglycemia (5.3 ± 0.1 mmol/L) and insulinemia (46 ± 6 pmol/L) during day 2 exercise studies, GABA A activation with alprazolam during day 1 euglycemia resulted in significant blunting of plasma epinephrine, norepinephrine, glucagon, cortisol, and growth hormone responses. Lipolysis (glycerol, nonesterified fatty acids) and endogenous glucose production during exercise were also reduced, and glucose infusion rates were increased following prior euglycemia with alprazolam. Prior hypoglycemia with alprazolam resulted in further reduction of glucagon and cortisol responses during exercise. We conclude that prior activation of GABA A pathways can play a significant role in blunting key autonomous nervous system, neuroendocrine, and metabolic physiologic responses during next-day exercise in healthy man.

Clinical use of insulin degludec

The limitations of current basal insulin preparations include concerns related to their pharmacokinetic and pharmacodynamic properties, hypoglycaemia, weight gain, and perception of management complexity, including rigid dosing schedules. Insulin degludec (IDeg) is a novel basal insulin with improved pharmacokinetic and pharmacodynamic properties compared to insulin glargine (IGlar) including a long half-life of ∼25 h and a duration of action >42 h at steady state, providing a flat and stable blood glucose-lowering effect when injected once daily. Evidence from phase 3a clinical trials with a treat-to-target design in patients with type 1 and type 2 diabetes has shown that IDeg has similar efficacy to IGlar, with a 9% and 26% reduction in risk of overall and nocturnal hypoglycaemia, respectively (in the pooled population) during the entire treatment period, and a 16% and 32% reduction during the maintenance period, respectively. Given its pharmacodynamic properties, IDeg offers a broad dosing window, allowing for flexible dose administration, if required. Two different formulations of IDeg are available (100 units/mL [U100] and 200 units/mL), the latter providing the same IDeg dose as the U100 formulation in half the injection volume. The unique pharmacokinetic profile of IDeg facilitates glycaemic control while minimising the risk of nocturnal hypoglycaemia.

[Clinical recommendations for sport practice in diabetic patients (RECORD Guide). Diabetes Mellitus Working Group of the Spanish Society of Endocrinology and Nutrition (SEEN)]

Sporting activity is becoming a common practice in patients with diabetes mellitus (DM). This situation requires both a preliminary medical assessment and a wide range of changes in treatment which have scarcely been addressed in medical literature.

OBJECTIVE

To prepare a clinical guideline on the medical approach to patients with diabetes who practice sport regularly.

METHODS

An expert panel from the Diabetes Mellitus Working Group of the Spanish Society of Endocrinology and Nutrition (SEEN) reviewed the most relevant literature in each of the sections. Based both on this review and on data from the experience of a number of athletes with DM, a number of recommendations were agreed within each section. Finally, the Working Group and representatives of the SEEN jointly discussed all these recommendations.

CONCLUSION

The guideline provides recommendations ranging from medical assessment before patients with DM start to practice sport to actions during and after physical activity. Recommendations are also given on aspects such as the impact of sport on blood glucose control, training schemes, or special risk situations.

Physical activity and type 1 diabetes: time for a rewire?

While being physically active bestows many health benefits on individuals with type 1 diabetes, their overall blood glucose control is not enhanced without an effective balance of insulin dosing and food intake to maintain euglycemia before, during, and after exercise of all types. At present, a number of technological advances are already available to insulin users who desire to be physically active with optimal blood glucose control, although a number of limitations to those devices remain. In addition to continued improvements to existing technologies and introduction of new ones, finding ways to integrate all of the available data to optimize blood glucose control and performance during and following exercise will likely involve development of "smart" calculators, enhanced closed-loop systems that are able to use additional inputs and learn, and social aspects that allow devices to meet the needs of the users.

Ischemia-reperfusion injury and hypoglycemia risk in insulin-treated T1DM rats following different modalities of regular exercise

While regular exercise is known to improve cardiovascular function, individuals with type 1 diabetes mellitus (T1DM) have an increased risk for exercise-induced hypoglycemia. Clinical data suggest that higher intensities of acute exercise may alleviate the onset of hypoglycemia; however, the cardiovascular benefit from these forms of exercise in patients with T1DM has yet to be established. The purpose of this study was to investigate the cardiovascular benefit of different regular exercise regimes, while monitoring blood glucose concentrations during the post-exercise period. Fifty rats (8-week-old Sprague-Dawley male) were equally divided into the following groups: nondiabetic sedentary (C), diabetic sedentary (DS), diabetic low-intensity aerobic exercise (DL), diabetic high-intensity aerobic exercise (DH) or diabetic resistance exercise (DR). Diabetes was induced using multiple streptozotocin injections (5×; 20 mg/kg) while subcutaneous insulin pellets maintained glycemia in a range typical for individuals that exercise with T1DM. Exercise consisted of six weeks of treadmill running (DL and DH) or weighted ladder climbs (DR). The cardiovascular benefit of each exercise program was determined by the myocardial recovery from ischemia-reperfusion injury. Exercise-related cardiovascular protection was dependent on the exercise modality, whereby DH demonstrated the greatest protection following an ischemic-reperfusion injury. Each exercise modality caused a significant decline in blood glucose in the post-exercise period; however, blood glucose levels did not reach hypoglycemic concentrations (<3.0 mmol/L) throughout the exercise intervention. These results suggest that elevating blood glucose concentrations prior to exercise allows patients with T1DM to perform exercise that is beneficial to the myocardium without the accompanying risk of hypoglycemia.

A review of the pharmacological properties of insulin degludec and their clinical relevance

Insulin degludec (IDeg) is a new-generation basal insulin with an ultra-long duration of action. To date, a large number of studies have been conducted to investigate the pharmacokinetic and pharmacodynamic properties of IDeg. Standardised methods for collection and analysis of blood samples (for pharmacokinetic endpoints) and euglycaemic clamp procedures (for pharmacodynamic endpoints) were applied across studies to enable cross-study evaluation of important pharmacokinetic and pharmacodynamic parameters. Data show that IDeg has a half-life of >25 h [compared with ~12 h for insulin glargine (IGlar)] and reaches steady state within 3 days of administration in all patient populations investigated. The pharmacokinetic profile of IDeg demonstrates an even distribution of exposure across one dosing interval. The pharmacodynamic profile of IDeg is flat and stable, demonstrated by an even distribution of glucose-lowering effect across all four 6-h intervals in a 24-h period (one dosing day). These properties were consistently demonstrated across different type 1 and type 2 diabetes mellitus patient populations, including those from different ethnic origins (both males and females with type 2 diabetes), the elderly, and patients with hepatic or renal impairment. IDeg has an ultra-long duration of action exceeding 42 h and demonstrates four times lower day-to-day within-subject variability in glucose-lowering effect than IGlar. This review discusses the pharmacokinetic and pharmacodynamic data accumulated thus far, and the relevance of these results from a clinical perspective.

Adding heart rate signal to a control-to-range artificial pancreas system improves the protection against hypoglycemia during exercise in type 1 diabetes

BACKGROUND

We present a clinical trial establishing the feasibility of a control-to-range (CTR) closed-loop system informed by heart rate (HR) and assess the effect of HR information added to CTR on the risk for hypoglycemia during and after exercise.

SUBJECTS AND METHODS

Twelve subjects with type 1 diabetes (five men, seven women; weight, 68.9 ± 3.1 kg; age, 38 ± 3.3 years; glycated hemoglobin, 6.9 ± 0.2%) participated in a randomized crossover clinical trial comparing CTR versus CTR+HR in two 26-h admissions, each including 30 min of mild exercise. The CTR algorithm was implemented in the DiAs portable artificial pancreas platform based on an Android(®) (Google, Mountainview, CA) smartphone. We assessed blood glucose (BG) decline during exercise, the Low BG Index (LBGI) (a measure of hypoglycemic risk), number of hypoglycemic episodes (BG <70 mg/dL) and overall glucose control (percentage time within the target range 70 mg/dL ≤ BG ≤ 180 mg/dL).

RESULTS

Using HR to inform the CTR algorithm reduced significantly the BG decline during exercise (P=0.022), indicated marginally lower LBGI (P=0.3) and fewer hypoglycemic events during exercise (none vs. two events; P=0.16), and resulted in overall higher percentage time within the target range (81% vs. 75%; P=0.2). LBGI and average BG remained unchanged overall, during recovery, and overnight.

CONCLUSIONS

HR-informed closed-loop control can be implemented in a portable artificial pancreas. Although closed loop has been shown to reduce hypoglycemia, adding HR signal may further limit the risk for hypoglycemia during and immediately after exercise. The most prominent effect of adding HR information is reduced BG decline during exercise, without deterioration of overall glycemic control.

Insulin degludec--the impact of a new basal insulin on care in type 2 diabetes

Many patients with type 2 diabetes continue to have poor glycaemic control and would benefit from insulin therapy. However, resistance to the introduction of insulin therapy can be high on both the part of the healthcare provider and the patient. A number of new, long-acting basal insulins are in development that provide good metabolic control, but with a lower risk of hypoglycaemia than currently available insulins, and greater flexibility in dosing time from day to day. These attributes may address some of the current barriers to insulin initiation and intensification that currently limit the effectiveness of diabetes care.

Morphological assessment of pancreatic islet hormone content following aerobic exercise training in rats with poorly controlled Type 1 diabetes mellitus

Regular exercise has been shown to improve many complications of Type 1 diabetes mellitus (T1DM) including enhanced glucose tolerance and increased cardiac function. While exercise training has been shown to increase insulin content in pancreatic islets of rats with T1DM, experimental models were severely hyperglycemic and not undergoing insulin treatment. Further, research to date has yet to determine how exercise training alters glucagon content in pancreatic islets. The purpose of the present investigation was to determine the impact of a 10-week aerobic training program on pancreatic islet composition in insulin-treated rats with T1DM. Second, it was determined whether the acute, exercise-mediated reduction in blood glucose experienced in rats with T1DM would become larger in magnitude following aerobic exercise training. Diabetes was induced in male Sprague-Dawley rats by multiple low dose injections of streptozotocin (20mg/kg i.p.) and moderate intensity aerobic exercise training was performed on a motorized treadmill for one hour per day for a total of 10 weeks. Rats with T1DM demonstrated significantly less islet insulin, and significantly more islet glucagon hormone content compared with non-T1DM rats, which did not significantly change following aerobic training. The reduction in blood glucose in response to a single exercise bout was similar across 10 weeks of training. Results also support the view that different subpopulations of islets exist, as small islets (<50 μm diameter) had significantly more insulin and glucagon in rats with and without T1DM.

Hypoglycemia: The neglected complication

Hypoglycemia is an important complication of glucose-lowering therapy in patients with diabetes mellitus. Attempts made at intensive glycemic control invariably increases the risk of hypoglycemia. A six-fold increase in deaths due to diabetes has been attributed to patients experiencing severe hypoglycemia in comparison to those not experiencing severe hypoglycemia Repeated episodes of hypoglycemia can lead to impairment of the counter-regulatory system with the potential for development of hypoglycemia unawareness. The short- and long-term complications of diabetes related hypoglycemia include precipitation of acute cerebrovascular disease, myocardial infarction, neurocognitive dysfunction, retinal cell death and loss of vision in addition to health-related quality of life issues pertaining to sleep, driving, employment, recreational activities involving exercise and travel. There is an urgent need to examine the clinical spectrum and burden of hypoglycemia so that adequate control measures can be implemented against this neglected life-threatening complication. Early recognition of hypoglycemia risk factors, self-monitoring of blood glucose, selection of appropriate treatment regimens with minimal or no risk of hypoglycemia and appropriate educational programs for healthcare professionals and patients with diabetes are the major ways forward to maintain good glycemic control, minimize the risk of hypoglycemia and thereby prevent long-term complications.

Whole-body glucose oxidation rate during prolonged exercise in type 1 diabetic patients under usual life conditions

OBJECTIVE

Fuel oxidation during exercise was studied in type 1 insulin-dependent (T1DM) patients mainly under quite constant insulin and glycemia; these protocols, however, likely do not reflect patients' usual metabolic conditions. The glucose oxidation rate (GLUox) in T1DM patients under usual life conditions was thus investigated during prolonged exercise (3-h) and its behavior was described mathematically.

MATERIALS/METHODS

Whole-body GLUox was determined in eight T1DM patients (4/8 M; aged 35-59 years) and eight well-matched healthy subjects. Venous blood was drawn prior to and every 30 min until the end of exercise; glycemia, insulin, cortisol, and growth hormone concentrations were determined. Oxygen consumption, carbon dioxide production, and ventilation were measured at rest and thereafter every 30 min of the exercise. To prevent hypoglycemia, patients were given fruit fudge (93% sucrose) prior to / during exercise.

RESULTS

Insulin concentration and glycemia were significantly higher in patients across the entire exercise period (group effect, p<0.001 for both). GLUox decreased significantly with increasing exercise duration (time effect, p<0.001), but no significant difference was detected between the two groups (group effect, p=NS). GLUox, expressed as the percentage of the starting value, was described by an exponential function showing a time constant of 90 min (n=96; mean corrected R(2)=0.666).

CONCLUSIONS

GLUox in T1DM patients was not significantly different from the rate observed in the control subjects. The function describing the time course of GLUox may be useful to correct an estimated GLUox for the duration of exercise and help T1DM patients avoiding exercise-induced glycemic imbalances.