Biological and behavioural determinants of the frequency of mild, biochemical hypoglycaemia in patients with Type 1 diabetes on multiple insulin injection therapy

Recurrent Hypoglycemia Exacerbates Cerebral Ischemic Damage in Diabetic Rats via Enhanced Post-Ischemic Mitochondrial Dysfunction

Diabetes significantly increases the risk of stroke and post-stroke mortality. Recurrent hypoglycemia (RH) is common among diabetes patients owing to glucose-lowering therapies. Earlier, we showed that RH in a rat model of insulin-dependent diabetes exacerbates cerebral ischemic damage. Impaired mitochondrial function has been implicated as a central player in the development of cerebral ischemic damage. Hypoglycemia is also known to affect mitochondrial functioning. The present study tested the hypothesis that prior exposure of insulin-treated diabetic (ITD) rats to RH exacerbates brain damage via enhanced post-ischemic mitochondrial dysfunction. In a rat model of streptozotocin-induced diabetes, we evaluated post-ischemic mitochondrial function in RH-exposed ITD rats. Rats were exposed to five episodes of moderate hypoglycemia prior to the induction of cerebral ischemia. We also evaluated the impact of RH, both alone and in combination with cerebral ischemia, on cognitive function using the Barnes circular platform maze test. We observed that RH exposure to ITD rats leads to increased cerebral ischemic damage and decreased mitochondrial complex I activity. Exposure of ITD rats to RH impaired spatial learning and memory. Our results demonstrate that RH exposure to ITD rats potentially increases post-ischemic damage via enhanced post-ischemic mitochondrial dysfunction.

Prevention of hypoglycemia-induced hippocampal neuronal death by N-acetyl-L-cysteine (NAC)

Type 1 and type 2 diabetic patients who are treated with insulin or other blood glucose reducing agents for tight control of blood glucose levels are frequently at risk of experiencing severe hypoglycemia which can lead to seizures, loss of consciousness and death. Hypoglycemic neuronal cell death is not a simple result of low glucose supply to the brain, but, instead, results from a cell death signaling pathway that is started by the re-administration of glucose after glucose deprivation. Zinc is a biologically important element for physiological function of central nervous system. However, excessive zinc release from the presynaptic terminals and subsequent translocation into the postsynaptic neurons may contribute to neuronal death following hypoglycemia. N-acetyl-L-cysteine (NAC) acts as a zinc chelator that alleviates zinc-induced neuronal death processes. In addition, NAC restores levels of neuronal glutathione (GSH), a potent antioxidant, by providing a cell-permeable source of cysteine. Thus, we hypothesized that NAC treatment can reduce neuronal cell death, not only by increasing GSH concentration but also by zinc chelation. As a result, we found that NAC decreased the oxidative stress, zinc release and translocation, and improved the level of glutathione. Therefore, NAC administration alleviated hippocampal neuron death in hypoglycemia-induced rats.

Neurologic damage in hypoglycemia

Hypoglycemia occurs in diabetic patients as a consequence of treatment with hypoglycemic agents, in insulinoma patients as a result of excessive insulin production, and in infants as a result of abnormal regulation of metabolism. Profound hypoglycemia can cause structural and functional disturbances in both the central (CNS) and the peripheral nervous system (PNS). The brain is damaged by a short and severe episode of hypoglycemia, whereas PNS pathology appears after a mild and prolonged episode. In the CNS, damaged mitochondria, elevated intracellular Ca2(+) level, released cytochrome c to the cytosol, extensive production of superoxide, increased caspase-3 activity, release of aspartate and glutamate from presynaptic terminals, and altered biosynthetic machinery can lead to neuronal cell death in the brain. Considering the PNS, chronic hypoglycemia is associated with delayed motor and sensory conduction velocities in peripheral nerves. With respect to pathology, hypoglycemic neuropathy in the PNS is characterized by Wallerian-like axonal degeneration that starts at the nerve terminal and progresses to a more proximal part of the axon, and motor axons to the muscles may be more severely damaged than sensory axons. Since excitatory neurotransmitters primarily involve the neuron in the CNS, this "dying back" pattern of axonal damage in the PNS may involve mechanisms other than excitotoxicity.

Evaluating the cost-effectiveness of reduced mild hypoglycaemia in subjects with Type 1 diabetes treated with insulin detemir or NPH insulin in Denmark, Sweden, Finland and the Netherlands

AIMS

To estimate short-term cost-effectiveness of insulin detemir vs. NPH insulin based on the incidence of mild hypoglycaemia in subjects with Type 1 diabetes in Denmark, Sweden, Finland and the Netherlands.

METHODS

A model was developed to evaluate cost-effectiveness based on mild (self-treated) hypoglycaemia and pharmacy costs over 1 year. Published rates of mild hypoglycaemia were used for NPH insulin and insulin detemir. Effectiveness was calculated in terms of quality-adjusted life expectancy. Pharmacy costs were accounted using published prices and defined daily doses for both insulins. Costs were expressed in 2010 euros (€).

RESULTS

Treatment with insulin detemir was associated with fewer mild hypoglycaemic events than NPH insulin (mean rates of 26.3 vs. 35.5 events per person-year), leading to an improvement in mean quality-adjusted life expectancy of approximately 0.019 (0.030) quality-adjusted life years (standard deviation). Annual costs were € 573.55 (110.42) vs. € 332.76 (62.18) in Denmark for insulin detemir and NPH insulin, respectively. These values were € 545.79 (106.54) vs. € 306.12 (57.78) in Sweden, € 720.10 (140.74) vs. € 408.73 (78.61) in Finland and € 584.01 (109.47) vs. € 359.60 (64.84) in the Netherlands. Incremental cost-effectiveness ratios were approximately € 12,644 (Denmark), € 12,612 (Sweden), € 16,568 (Finland) and € 12,216 (the Netherlands) per quality-adjusted life year gained for insulin detemir vs. NPH insulin.

CONCLUSIONS

Insulin detemir is likely to be cost-effective vs. NPH insulin in subjects with Type 1 diabetes in Denmark, Sweden, Finland and the Netherlands. Increased pharmacy costs with insulin detemir should not be a barrier to therapy based on these findings.

Uncovering undetected hypoglycemic events

Hypoglycemia is the rate-limiting factor that often prevents patients with diabetes from safely and effectively achieving their glycemic goals. Recent studies have reported that severe hypoglycemia is associated with a significant increase in the adjusted risks of major macrovascular events, major microvascular events, and mortality. Minor hypoglycemic episodes can also have serious implications for patient health, psychological well being, and adherence to treatment regimens. Hypoglycemic events can impact the health economics of the patient, their employer, and third-party payers. Insulin treatment is a key predictor of hypoglycemia, with one large population-based study reporting an overall prevalence of 7.1% (type 1 diabetes mellitus) and 7.3% (type 2 diabetes mellitus) in insulin-treated patients, compared with 0.8% in patients with type 2 diabetes treated with an oral sulfonylurea. Patients with type 1 diabetes typically experience symptomatic hypoglycemia on average twice weekly and severe hypoglycemia once annually. The progressive loss of islet cell function in patients with type 2 diabetes results in a higher risk of both symptomatic and unrecognized hypoglycemia over time. Patients with diabetes who become hypoglycemic are also more susceptible to developing defective counter-regulation, also known as hypoglycemia awareness autonomic failure, which is life-threatening and must be aggressively addressed. In patients unable to recognize hypoglycemia symptoms, frequent home monitoring or use of continuous glucose sensors are critical. Primary care physicians play a key role in the prevention and management of hypoglycemia in patients with diabetes, particularly in those requiring intensive insulin therapy, yet physicians are often unaware of the multitude of consequences of hypoglycemia or how to deal with them. Careful monitoring, adherence to guidelines, and use of optimal treatment combinations are all important steps toward improving care in patients with diabetes. The most important goals are for primary care physicians to recognize that every patient treated with antihyperglycemic medications is at risk of iatrogenic hypoglycemia and to ask patients about hypoglycemia at every visit.

Recent advances in the prevention of hypoglycemia in type 1 diabetes

Iatrogenic hypoglycemia is one of the chief barriers to optimal glycemic control in people with type 1 diabetes (T1D). As a common contributor to morbidity and mortality in T1D, severe hypoglycemia (SH) is also a major fear for people with T1D and their families. Consequently, fear of hypoglycemia and hypoglycemia-avoidant behaviors are predominant limiting factors in achieving euglycemia in people with T1D. Nocturnal SH and hypoglycemia unawareness are prevalent obstacles in the detection of hypoglycemia which further impair the prevention and treatment of SH. Various strategies and technologies have already been developed to help detect and prevent hypoglycemia, including improved patient education, frequent self-monitoring of blood glucose levels, the use of rapid-acting and basal insulin analogs, continuous subcutaneous insulin infusion therapy, exercise-related insulin modifications, and continuous glucose monitors. The efficacy of these methods is well established, but further advances are still needed. The purpose of this review is to describe these currently available methods and to emphasize recent progress related to the prevention of hypoglycemia in T1D.

Flexible insulin therapy with glargine insulin improved glycemic control and reduced severe hypoglycemia among preschool-aged children with type 1 diabetes mellitus

BACKGROUND AND OBJECTIVES

Insulin replacement regimens now stress the importance of administering throughout the day insulin doses that are based on flexible food choices and focusing on improved metabolic control. A flexible multiple daily insulin (FMDI) regimen (premeal lispro plus bedtime glargine) results in lower hemoglobin A1c (HbA1c) levels and fewer hypoglycemic episodes than does a multiple daily insulin (MDI) regimen among school-aged children and adolescents with type 1 diabetes mellitus (DM). The purpose of this study was to determine the feasibility of FMDI therapy for a group of preschool-aged children with type 1 DM who were transitioned from MDI therapy (premeal lispro plus ultralente insulin twice per day), by comparing BMI, total daily insulin requirements, HbA1c levels, and episodes of severe hypoglycemia.

RESEARCH DESIGN AND METHODS

Data were collected over a 2-year period, during quarterly DM clinic visits, from 35 patients (17 female patients and 18 male patients, 4.8 +/- 1.0 years of age) who had received MDI insulin therapy for > or =1 year before being transitioned to a FMDI regimen.

RESULTS

Although there was no significant change in BMI with FMDI therapy (17.1 +/- 1.8 kg/m2 vs 17.0 +/- 1.7 kg/m2), 43% of patients (6 female subjects and 9 male subjects) were overweight (BMI of >85th percentile for age) both before and after treatment. The total daily insulin requirement (0.67 +/- 0.13 U/kg per day vs 0.78 +/- 0.14 U/kg per day) and bolus/basal insulin ratio (1.1 +/- 0.4 vs 1.9 +/- 0.6) were significantly increased and overall glycemic control was improved after transition to FMDI therapy (HbA1c levels: 8.8 +/- 0.9% vs 8.3 +/- 0.8%). However, HbA1c levels improved only among normal-weight subjects (9.0 +/- 1.0% vs 8.3 +/- 1.0%) and not among overweight subjects (8.7 +/- 0.7% vs 8.4 +/- 0.6%) after FMDI therapy. The overall rate of severe hypoglycemia was significantly decreased with the FMDI regimen (25.5 events per 100 patient-years vs 10.6 events per 100 patient-years) but again only for normal-weight children (29.7 events per 100 patient-years vs 7.4 events per 100 patient-years).

CONCLUSIONS

The use of FMDI therapy with glargine among preschool-aged children with type 1 DM was associated with improved overall glycemic control and decreased frequency of severe hypoglycemia. Although our study did not have a control group, these findings suggest that FMDI regimens may be a feasible therapeutic alternative to MDI treatment for preschool-aged children with type 1 DM. However, excess body weight status appeared to preclude a desirable therapeutic response in this group of patients.

Beneficial effects of continuous subcutaneous insulin infusion and flexible multiple daily insulin regimen using insulin glargine in type 1 diabetes

OBJECTIVE

The aim of this study was to evaluate the metabolic effects of continuous subcutaneous insulin infusion (CSII) with flexible multiple daily insulin (FMDI; premeal lispro + bedtime glargine) therapy as determined by glycosylated hemoglobin (HbA1c), body mass index (BMI), and hypoglycemic episodes in a group of patients who made the transition from multiple daily insulin (premeal lispro + bid ultralente) to either CSII or FMDI therapy.

METHODS

Data from 40 (27 female and 13 male) patients (10.1-17.8 years of age) who were on CSII and 40 age- and gender-matched (27 female and 13 male) patients (10.3-17.3 years of age) who were on FMDI were collected during regularly scheduled visits at a similar frequency over a 1-year period.

RESULTS

The total daily insulin dose did not change in CSII (0.97 +/- 0.24 vs 0.91 +/- 0.22 U/kg) and FMDI (0.98 +/- 0.21 vs 0.97 +/- 0.21 U/kg) patients, whereas the bolus:basal insulin ratio was significantly increased in both CSII (1.01 +/- 0.43 vs 1.32 +/- 0.52) and FMDI (1.07 +/- 0.0.41 vs 1.29 +/- 0.47) patients. The total cohort of CSII patients showed a decrease in HbA1c from 8.4 +/- 1.0% to 7.8 +/- 0.8%, whereas the FMDI cohort did not show a significant change in HbA1c (8.5 +/- 1.1% to 8.2 +/- 0.9%). However, 40% of the CSII group and 22.5% of the FMDI group showed > or =1.0% improvement in HbA1c. Also, a similar number of patients in CSII (52.5%; 8.0 +/- 1.1 to 7.2 +/- 0.5%) and FMDI (47.5%; 8.0 +/- 0.5% to 7.5 +/- 0.4%) maintained or achieved target HbA1c values <8.0%. The BMI increased significantly in the CSII group (21.6 +/- 3.2 vs 23.0 +/- 3.0 kg/m2) but did not change in the FMDI group (21.9 +/- 3.9 vs 22.6 +/- 3.8 kg/m2). There was a significant reduction in the rate of severe hypoglycemia (events/100 patient-years) in both cohorts: 20.6 to 8.2 in the CSII and 18.8 to 7.5 in the FMDI. Similarly, the rate of moderate hypoglycemia decreased in both CSII (68.3-35.4) and FMDI (56.3-30.4).

CONCLUSIONS

CSII therapy resulted in a significant improvement in HbA 1c in the entire group, whereas FMDI therapy improved HbA1c in only a subgroup of patients. However, almost half of the patients in each of the treatment groups maintained or achieved target glycemic control. Both CSII and FMDI treatment groups demonstrated a decreased rate of hypoglycemia without an abnormal increase in BMI. Although the design of this study does not allow direct comparison of the metabolic effects of CSII and FMDI therapies, both regimens seem to be superior to basal ultralente and lispro multiple daily insulin regimen and offer desirable therapeutic alternatives in pediatric diabetes care.

Biochemical hypoglycemia in female nurses during clinical shift work

Female nurses in Japan commonly experience symptoms similar to those of hypoglycemia while working. Biochemical hypoglycemia can lead to impaired cognition; thus, it is important to know the prevalence of biochemical hypoglycemia among nurses. Five hundred and sixty-eight female nurses (53% of the target population) in four hospitals completed questionnaires. They determined their blood glucose levels 12 times, at four points during three shifts. Fifty-seven nurses (10%) recorded biochemical hypoglycemia (<or=3.0 mM) at least once. Multivariate analysis revealed three independent risk factors for hypoglycemia: higher coefficient of variation of blood glucose level, lower body mass index, and not smoking. Subjective symptoms were not associated with hypoglycemia. More research on hypoglycemia is needed in order to improve working environment for nurses.