Double blind clinical and laboratory study of hypoglycaemia with human and porcine insulin in diabetic patients reporting hypoglycaemia unawareness after transferring to human insulin

Transitioning to a national (New Zealand) sole supply scheme for glucose meters: lessons learned, problems yet to be solved

This case study describes the clinical impact of moving to a single brand of glucose test strips. In 2013 the New Zealand public health system completed a move to procure test strips at a significant discount. The associated direct savings is estimated at around 40% of the total glucose strip budget. Half the local diabetes population undertake glucose monitoring using government-funded diabetes supplies. These patients no longer have a choice of brand of meters and strips. Although the majority of patients adapted well to this change, a small percentage did not. Also, some consumers expressed concerns about analytical performance of the new strips, when used in everyday life. A pragmatic postmarketing surveillance system, designed with consumer input, may help address these residual concerns.

Differential changes in brain glucose metabolism during hypoglycaemia accompany loss of hypoglycaemia awareness in men with type 1 diabetes mellitus. An [11C]-3-O-methyl-D-glucose PET study

AIMS/HYPOTHESIS

Hypoglycaemia unawareness in type 1 diabetes increases the risk of severe hypoglycaemia and impairs quality of life for people with diabetes. To explore the central mechanisms of hypoglycaemia awareness, we used [11C]-3-O-methyl-D-glucose (CMG) positron emission tomography (PET) to measure changes in global and regional brain glucose metabolism between euglycaemia and hypoglycaemia in aware and unaware diabetic subjects.

MATERIALS AND METHODS

Twelve men with type 1 diabetes, of whom six were characterised as aware and six as unaware of hypoglycaemia, underwent two CMG-PET brain scans while plasma glucose was controlled by insulin and glucose infusion either at euglycaemia (5 mmol/l) or at hypoglycaemia (2.6 mmol/l) in random order.

RESULTS

With hypoglycaemia, symptoms and sweating occurred only in the aware group. Brain glucose content fell in both groups (p=0.0002; aware, 1.18+/-0.45 to 0.02+/-0.2 mmol/l; unaware, 1.07+/-0.46 to 0.19+/-0.23 mmol/l), with a relative increase in tracer uptake in prefrontal cortical regions, including the anterior cingulate. No detectable differences were found between groups in global brain glucose transport parameters (K1, k2). The cerebral metabolic rate for glucose (CMRglc) showed a relative rise in the aware subjects (11.839+/-2.432 to 13.958+/-2.372) and a fall in the unaware subjects (from 12.457+/-1.938 to 10.16+/-0.801 micromol 100 g(-1) min(-1), p=0.043).

CONCLUSIONS/INTERPRETATION

Hypoglycaemia is associated with reduced brain glucose content in aware and unaware subjects, with a relative preservation of metabolism in areas associated with sympathetic activation. The relative rise in global glucose metabolic rate seen in aware subjects during hypoglycaemia contrasted with the relative fall in the unaware subjects and suggests that cortical neuronal activation is a necessary correlate of the state of hypoglycaemia awareness.

'Human' insulin versus animal insulin in people with diabetes mellitus

BACKGROUND

Human insulin was introduced for the routine treatment of diabetes mellitus in the early 1980s without adequate comparison of efficacy to animal insulin preparations. First reports of altered hypoglycaemia awareness after transfer to human insulin made physicians and especially patients uncertain about potential adverse effects of human insulin.

OBJECTIVES

To assess the effects of different insulin species by evaluating their efficacy (in particular glycaemic control) and adverse effects profile (mainly hypoglycaemia).

SEARCH STRATEGY

A highly sensitive search for randomised controlled trials combined with key terms for identifying studies on human versus animal insulin was performed using The Cochrane Library, MEDLINE and EMBASE. We also searched reference lists and databases of ongoing trials. Date of latest search: July 2004.

SELECTION CRITERIA

We included randomised controlled clinical trials with diabetic patients of all ages that compared human to animal (for the most part purified porcine) insulin. Trial duration had to be at least one month in order to achieve reliable results on the main outcome parameter glycated haemoglobin.

DATA COLLECTION AND ANALYSIS

Trial selection as well as evaluation of study quality was performed by two independent reviewers. The quality of reporting of each trial was assessed according to a modification of the quality criteria as specified by Schulz and by Jadad.

MAIN RESULTS

Altogether 2156 participants took part in the 45 randomised controlled studies that were discovered through extensive search efforts. Though many studies had a randomised, double-blind design, most studies were of poor methodological quality. Purified porcine and semi-synthetic insulin were most often investigated. No significant differences in metabolic control or hypoglycaemic episodes between various insulin species could be elucidated. Insulin dose and insulin antibodies did not show relevant dissimilarities.

AUTHORS' CONCLUSIONS

A comparison of the effects of human and animal insulin as well as of the adverse reaction profile did not show clinically relevant differences. Many patient-oriented outcomes like health-related quality of life or diabetes complications and mortality were never investigated in high-quality randomised clinical trials. The story of the introduction of human insulin might be repeated by contemporary launching campaigns to introduce pharmaceutical and technological innovations that are not backed up by sufficient proof of their advantages and safety.

Strategies for managing the diabetic patient

Diabetes mellitus is now classified as either 'type 1' (failure of endogenous insulin production) or 'type 2' ('insulin resistance') and can be diagnosed if fasting blood glucose is >6.1 mmol/l (110mg/dl) on two separate occasions or there is unequivocal hyperglycaemia with acute metabolic decompensation or obvious symptoms. The prevalence of the disease is rising and may be as great as 12-14% in western populations aged over 40 years. Diabetes is complicated by micro- and macrovascular consequences of chronically elevated blood glucose concentrations, and diabetic patients are over-represented in hospital populations, particularly among patients requiring surgical interventions. It is associated with increased perioperative mortality and morbidity. Evidence is now accumulating that intensive glycaemic monitoring and the administration of insulin infusions to achieve tight glycaemic control are associated with an improvement of both perioperative mortality and morbidity.

Are hypoglycaemia and other adverse effects similar among sulphonylureas?

This review provides an updated overview of the adverse effects of sulphonylureas and identifies factors associated with variation in adverse effect rates among sulphonylureas published by different studies. A search of Medline, Embase, Current Contents and Cochrane Library was conducted to identify all papers related to sulphonylureas and adverse effects published from 1950-2001. The reference lists of all relevant papers were also searched for additional articles. The frequency of sulphonylurea-induced hypoglycaemia varied from 1.8-59%. Severe hypoglycaemia due to sulphonylurea use has been reported from 1.9-3.5%. Variation in hypoglycaemia rates may be due to differences in definitions, methods to detect and to collect information, patient characteristics, patient knowledge of the condition, threshold for symptoms, and activity level during hypoglycaemia. Other adverse effects associated with sulphonylurea use include bodyweight gain, gastrointestinal distress, disulphiram-like syndrome, dermatological reactions, haematological changes, ocular problems, and the syndrome of inappropriate secretion of antidiuretic hormone. Bodyweight gain has been reported to vary from 1.7-4.8 kg, according to the United Kingdom Prospective Diabetes Study (UKPDS-33). Controversy exists regarding cardiovascular adverse effects, but the consensus is to exercise caution in the use of these drugs as first-line therapy for patients with diabetes mellitus and coronary artery disease. The benefits of sulphonylurea treatment should be weighed against the risks associated with them. More work in this area is needed to homogenise the definition of hypoglycaemia, to get consensus on the methods for detection and data collection, as well as to further patient and physician education.

'Human' insulin versus animal insulin in people with diabetes mellitus

BACKGROUND

Human insulin was introduced for the routine treatment of diabetes mellitus in the early 1980s without adequate comparison of efficacy to animal insulin preparations. First reports of altered hypoglycaemia awareness after transfer to human insulin made physicians and especially patients uncertain about potential adverse effects of human insulin.

OBJECTIVES

To assess the effects of different insulin species by evaluating their efficacy (in particular glycaemic control) and adverse effects profile (mainly hypoglycaemia).

SEARCH STRATEGY

A highly sensitive search for randomised controlled trials combined with key terms for identifying studies on human versus animal insulin was performed using the Cochrane Library (issue 2, 2002), Medline (1966 to May, 2002) and Embase (1974 to February, 2002). We also searched reference lists and databases of ongoing trials. Date of latest search: May 2002.

SELECTION CRITERIA

We included randomised controlled clinical trials with diabetic patients of all ages that compared human to animal (for the most part purified porcine) insulin. Trial duration had to be at least one month in order to achieve reliable results on the main outcome parameter glycated haemoglobin.

DATA COLLECTION AND ANALYSIS

Trial selection as well as evaluation of study quality was performed by two independent reviewers. The quality of reporting of each trial was assessed according to a modification of the quality criteria as specified by Schulz and by Jadad.

MAIN RESULTS

Altogether 2156 participants took part in the 45 randomised controlled studies that were discovered through extensive search efforts. Though many studies had a randomised, double-blind design, most studies were of poor methodological quality. Purified porcine and semi-synthetic insulin were most often investigated. No significant differences in metabolic control or hypoglycaemic episodes between various insulin species could be elucidated. Insulin dose and insulin antibodies did not show relevant dissimilarities.

REVIEWER'S CONCLUSIONS

A comparison of the effects of human and animal insulin as well as of the adverse reaction profile did not show clinically relevant differences. Many patient-oriented outcomes like health-related quality of life or diabetes complications and mortality were never investigated in high-quality randomised clinical trials. The story of the introduction of human insulin might be repeated by contemporary launching campaigns to introduce pharmaceutical and technological innovations that are not backed up by sufficient proof of their advantages and safety.

Human versus animal insulin in people with diabetes mellitus. A systematic review

This review is in accordance with the findings of the systematic review of Airey et al [18] with respect to the absence of a differential effect on hypoglycemia between human and animal insulin. For the first time, however, the review compares the relative efficacies of human and animal insulin, which indicates that human insulin was introduced without proof of being superior to animal insulin. Studies have not assessed patient-centered outcomes [41,42], such as patient satisfaction, health-related quality of life, and diabetes-related morbidity. Randomized trials did not report on qualitative assessments of patients' experiences when using different insulin species. Because history tends to repeat itself, we probably will be faced with other "innovations" (e.g., insulin analogs) evaluated in clinical trials tht focus on surrogate outcomes followed by marketing of insulins "proved" to be effective in short-term, underpowered, and badly executed studies.

Physiological responses during hypoglycaemia induced by regular human insulin or a novel human analogue, insulin glargine

AIM

Glargine, a product of recombinant technology, has different structural and physicochemical properties compared with native human insulin. We determined whether such differences are associated with alterations in the responses to hypoglycaemia induced by glargine.

METHODS

Nineteen adults (six healthy and 13 with type 1 diabetes) underwent a 5-h hyperinsulinaemic (2 mU/kg/min(-1)) stepped hypoglycaemic clamps (hourly targets of 4.7, 4.2, 3.6, 3.1 and 2.5 mmol/l, respectively) on two occasions using intravenous infusion of regular human insulin or glargine, in random sequence. Hypoglycaemic symptoms, counter-regulatory hormones and glucose disposal rates were assessed at intervals throughout the clamps. A 1-week 'wash out' period was observed between studies.

RESULTS

The peak total symptoms scores (mean +/- s.e.m.) at nadir blood glucose (2.5 mmol/1) were 18.83 +/- 2.68 (healthy) and 17.46 +/- 3.62 (diabetic) during regular insulin, and 18.50 +/- 3.20 (healthy) and 19.08 +/- 3.83 (diabetic) during glargine infusion. The peak epinephrine levels during hypoglycaemia were 767.8 +/- 140.4 pg/ml (regular insulin) and 608.8 +/- 129.9 pg/ml (glargine) among healthy subjects, and 332.5 +/- 54.8 pg/ml (regular insulin) and 321.8 +/- 67.4 pg/ml (glargine) in diabetic patients. Diabetic patients had blunted glucagon responses during hypoglycaemia with either insulin. Both insulins also elicited similar rates of glucose disposal.

CONCLUSIONS

We conclude that insulin glargine and regular human insulin elicit comparable symptomatic and counter-regulatory hormonal responses during hypoglycaemia in healthy or diabetic subjects, and induce similar rates of glucose disposal. Since glargine is designed for subcutaneous (s.c.) use, it is possible (though unlikely) that our findings obtained using an intravenous protocol could differ from responses to hypoglycaemia induced by the s.c. route.

Hypoglycaemia induced by exogenous insulin--'human' and animal insulin compared

AIMS

A systematic review of the literature was carried out to examine whether published evidence suggests a difference in the frequency and awareness of hypoglycaemia induced by 'human' and animal insulin.

METHODS

The review identified randomized controlled trials and studies of other designs including observational comparisons, case series and case reports in which the use of 'human' insulin was compared to animal insulin in people with diabetes. These were identified from bibliographic databases and hand-searches of key journals. The main outcome measures were frequency, severity, awareness and symptoms of insulin induced hypoglycaemia.

RESULTS

Fifty-two randomized controlled trials, 37 of double-blind design, were identified which included one or more of the relevant outcome measures. Of these, 21 specifically investigated hypoglycaemic frequency and awareness as primary outcomes (six in people with previously reported reduced hypoglycaemic awareness). The remainder of the identified trials reported hypoglycaemic outcomes as a secondary or incidental outcome during comparative investigations of efficacy or immunogenicity. Seven of the double-blind studies reported differences in frequency of hypoglycaemia or awareness of symptoms, although none of the studies which selected subjects on the basis of previously reported impaired awareness demonstrated significant differences between insulin species. Four of the unblinded trials reported differences in hypoglycaemia. This reached statistical significance in two of the studies. A further 56 studies of other designs and case reports were considered. In addition to the 10 case reports describing individuals with impaired hypoglycaemic awareness, nine studies reported differences in the incidence and manifestation of hypoglycaemia during 'human' insulin treatment. Notably, none of the four population time trend studies found any relationship between the increasing use of 'human' insulin and hospital admission for hypoglycaemia or unexplained death among those with diabetes. The largest case series could find no support for the hypothesis that an influence of treatment with 'human' insulin on hypoglycaemia had contributed to any of the 50 deaths investigated. When all types of studies considered are ranked in order of rigour (according to the accepted 'hierarchy of evidence'), it is the least rigorous which lend most support to the notion that treatment with 'human' insulin has an effect on the frequency, severity or symptoms of hypoglycaemia.

CONCLUSIONS

Evidence does not support the contention that treatment with 'human' insulin per se affects the frequency, severity or symptoms of hypoglycaemia. However, a number of studies, mainly those of less rigorous design, describe an effect when people are transferred from animal insulin to 'human' insulin. It is not possible to state how common this is or whether the phenomenon is specific to 'human' insulin or an effect resulting from stricter glycaemic control (perhaps compounded, in some cases, by neurological complications in long-standing diabetes). This remaining uncertainty makes it essential that insulin from animal sources continues to be available so that clinicians and patients may retain this choice of treatment.

No differential effects of porcine and human insulin on muscle sympathetic nerve activity during euglycaemia or hypoglycaemia

On the basis of some clinical studies in diabetic patients, and experimental studies in normal humans, it has been suggested that hypoglycaemic autonomic responses are augmented with porcine (PI) compared to human insulin (HI). A difference in sensory processing has been reported following insulin-induced hypoglycaemia with PI compared to HI, and has been interpreted as different insulin effects on the central nervous system. In a double blind crossover comparison of HI and PI in nine healthy subjects, microneurographic recordings of muscle sympathetic nerve activity (MSNA) were performed, as well as measurements of cardiovascular and hormonal responses during a low dose hyperinsulinaemic euglycaemic glucose clamp (plasma insulin 60.1 +/- 1.9 mU ml-1 (mean +/- SEM)), followed by a period of insulin-induced hypoglycaemia. Plasma insulin and glucose were identical in the two sessions. Plasma glucose nadir during hypoglycaemia was 2.4 +/- 0.2 mmol l-1 for HI and 2.5 +/- 0.1 mmol l-1 for PI. During euglycaemia, MSNA increased from 24 +/- 2 to 34 +/- 3 and 23 +/- 2 to 30 +/- 2 burst/min (P:NS) for HI and PI, respectively, and during hypoglycaemia to 49 +/- 4 and 45 +/- 2 bursts min-1 (P:NS), respectively. The maximal hypoglycaemic increments of MSNA were not different (HI 15 +/- 4; PI 15 +/- 2 bursts min-1 (P:NS)) Responses of plasma noradrenaline and haemodynamic parameters did not differ either. This study does not indicate differing sympathetic responses to PI and HI in healthy humans. Evidence for a modulating effect of insulin on central sympathetic outflow was not found.

Hypoglycemia-induced cognitive dysfunction in diabetes mellitus: effect of hypoglycemia unawareness

Hypoglycemia results in cognitive dysfunction. The aim of this study was to assess and compare the degree of cognitive dysfunction experienced by insulin-dependent diabetic patients (IDDM) with hypoglycemia unawareness with patients with normal awareness of hypoglycemia. Cognitive function was examined in 10 patients who had normal awareness of the onset of hypoglycemia and 10 patients who had a history of impaired awareness of hypoglycemia. A hyperinsulinemic glucose clamp was used to manipulate blood glucose concentrations. Cognitive function was assessed using Rapid Visual Information Processing (RVIP), Trial Making B (TMB), Paced Auditory Serial Addition Test (PASAT) and Digit Symbol Substitution Test (DSST). Multivariate analysis of variance demonstrated a significant effect of hypoglycemia on cognitive function (p < 0.01). A trend was observed towards an overall effect of awareness on performance (p = 0.08). There were trends in the effects of awareness on RVIP correct responses across time (p = 0.07) and the interaction of awareness by study by TMB (p = 0.08). During hypoglycemia subjects with impaired awareness were less cautious in their responses (RVIP misses p = 0.03) and on recovery from hypoglycemia, their cognitive function remained abnormal (TMB p = 0.04, RVIP correct responses p = 0.02, RVIP misses p = 0.04). Thus, IDDM patients with hypoglycemia unawareness exhibited more profound cognitive dysfunction during acute hypoglycemia which persisted for longer following blood glucose recovery.

Binding of human, porcine and bovine insulin to insulin receptors from human brain, muscle and adipocytes and to expressed recombinant alternatively spliced insulin receptor isoforms

Previous studies have suggested that human and porcine insulin exert identical effects on blood glucose and counter-regulatory hormones but elicit different neurophysiological reactions. A major goal of the present study was to investigate whether this could be caused by different relative affinities of the insulins from different species to insulin receptors from the brain compared to other tissues. Insulin receptors isolated from human brain, muscle or adipocytes as well as from cultured cells over-expressing either of the human insulin receptor isoforms (exon 11- or exon 11 +) were immobilized to microwells coated with monoclonal anti-insulin receptor antibody. Subsequently the binding of human, porcine and bovine insulin was measured. While the receptors derived from the different tissues had different affinities for insulin, there were no tissue-specific differences in the relative binding of the insulins of the three species. The insulins of the three species were also not different with regard to their binding to the receptor isoforms. Finally, in human brain homogenates no differences in the degradation rates for human, porcine and bovine insulin were detected. Thus, our data do not support the hypothesis that different neurophysiological reactions during hypoglycaemia due to human or porcine insulin are caused by differences of the binding of the insulins to human brain insulin receptors or their degradation in the human brain.

Frequency, severity and symptomatology of hypoglycaemia: a comparative trial of human and porcine insulins in type 1 diabetic patients

A randomized, double-blind, cross-over trial was performed to compare the frequency, severity, and symptomatology of hypoglycaemia during treatment with porcine and human insulins. Forty patients with Type 1 diabetes (20 newly diagnosed and 20 with diabetes of 5-20 years duration) were treated with human and porcine insulins for consecutive 3-month periods, in random order. Episodes of hypoglycaemia were recorded prospectively with self-reporting of the presence and intensity of symptoms using a standardized scoring technique. Serial measurements of glycated haemoglobin and review of home blood glucose tests confirmed that similar glycaemic control was achieved with each insulin species. On comparison of the treatment periods with human and porcine insulins, no differences were demonstrated in the total frequency of symptomatic hypoglycaemia (3.10 vs 3.06 episodes patient-1 3-months-1; p = 0.94), the frequency of severe hypoglycaemia (0.1 vs 0.2 episodes patient-1 3-months-1; p = 0.44), the occurrence of asymptomatic biochemical hypoglycaemia (0.75 vs 0.68 episodes patient-1 3-months-1; p = 0.81), and the capillary blood glucose concentration at the onset of hypoglycaemic symptoms (2.6 +/- 0.2 vs 2.4 +/- 0.3 mmol l-1; p = 0.40), with all results being expressed for human vs porcine treatment periods, respectively. The symptoms of hypoglycaemia did not differ during the treatment periods with each insulin species. In conclusion, treatment with human insulin had no effect upon the symptomatic response to hypoglycaemia, did not increase the total frequency of hypoglycaemia, and did not emerge as a significant risk factor for severe hypoglycaemia in these patients.

Human insulin and hypoglycaemia: a literature survey

Thirty-nine clinical studies and 12 epidemiological reports comparing human insulin and porcine insulin were reviewed. Twenty-five studies (encompassing 338 subjects) showed identical symptoms and physiological response to acute hypoglycaemia overall. Fifteen studies (encompassing more than 1253 patients) showed identical incidence of hypoglycaemia overall and similar symptoms with the two types of insulin. Twelve studies showed identical incidence of hypoglycaemia overall with the two types of insulin. Thus, the overwhelming evidence from a large number of studies including a large number of patients suggests that: (1) human and porcine insulin do not provoke different hormonal responses to hypoglycaemia; (2) they do not cause different symptoms of hypoglycaemia; (3) the incidence of severe hypoglycaemia with human insulin does not differ from that of porcine insulin.

Changing from porcine to human insulin

The development of hypoglycaemia unawareness is associated with long duration of diabetes, improved glycaemic control, alcohol intake and recurrent hypoglycaemia. However, current evidence suggests that neither frequency of severe episodes nor mortality from hypoglycaemia are increased following a change from animal to human insulin. Nevertheless, a small number of patients continue to report an alteration in the nature of hypoglycaemic warning symptoms following a change in insulin species. This is possibly a consequence of a reduced catecholamine response to lowering blood glucose levels or to species differences in the effect of insulin on central nervous system function. In practical terms, it seems sensible to warn patients that the nature of the symptoms associated with hypoglycaemia might alter following conversion from porcine to human insulin. At the time of the changeover, patients should be encouraged to perform frequent blood glucose measurements. Also, the usual insulin dose should be reduced by 10% at the start of human insulin treatment. Other aspects of insulin treatment including injection technique, meal timing, exercise, etc. should be discussed. For patients who are convinced that loss of warning of hypoglycaemia occurred after conversion from porcine to human insulin, a change back to animal insulin would be preferred to relaxing glycaemic control in the first instance. Pressure should be brought to bear on the pharmaceutical industry to maintain the availability of animal insulins for the small number of patients who have experienced problems with human insulin.

Protection by lactate of cerebral function during hypoglycaemia

Severe hypoglycaemia with brain dysfunction limits intensified therapy in patients with insulin-dependent diabetes mellitus, despite evidence that such therapy reduces the risk of chronic complications of the disease. We have investigated the effect of infusing lactate (a potential non-glucose fuel for brain metabolism) on protective, symptomatic neurohumoral responses and on brain function during hypoglycaemia in seven healthy men. Elevation of lactate (within a physiological range) substantially diminished catecholamines, growth hormone, cortisol, and symptomatic responses to hypoglycaemia and lowered the glucose level at which these responses began. Glucagon responses were unaffected. Lactate was also associated with a significant lowering of the glucose level at which brain function deteriorated, suggesting that brain function was protected during the hypoglycaemia. The defect in counter-regulation is similar to that seen in hypoglycaemia-prone diabetic patients. Initiation of the protective responses to hypoglycaemia (except glucagon) can be delayed by supporting metabolism with an alternative metabolic fuel. Cerebral cortical dysfunction of severe hypoglycaemia is also delayed. Our demonstration that higher brain function can be protected during hypoglycaemia may have therapeutic potential.