Reproducibility and variability in the action of injected insulin

Insulin Tregopil: An Ultra-Fast Oral Recombinant Human Insulin Analog: Preclinical and Clinical Development in Diabetes Mellitus

Insulin therapy is indispensable for achieving glycemic control in all patients with type 1 diabetes mellitus and many patients with type 2 diabetes mellitus. Insulin injections are associated with negative connotations in patients owing to administration discomfort and adverse effects such as hypoglycemia and weight gain. Insulin administered orally can overcome these limitations by providing a convenient and effective mode of delivery with a potentially lower risk of hypoglycemia. Oral insulin mimics the physiologic process of insulin secretion, absorption into the portal circulation, and subsequent peripheral delivery, unlike the subcutaneous route that results in peripheral hyperinsulinemia. Insulin tregopil (IN-105), a new generation human recombinant insulin, methoxy (polyethylene glycol) hexanoyl human recombinant insulin, is developed by Biocon as an ultra-fast onset short-acting oral insulin analog. This recombinant oral insulin is a single short-chain amphiphilic oligomer modified with the covalent attachment of methoxy-triethylene-glycol-propionyl moiety at Lys-β29-amino group of the B-chain via an amide linkage. Sodium caprate, an excipient in the insulin tregopil formulation, is a permeation enhancer that increases its absorption through the gastrointestinal tract. Also, meal composition has been shown to non-significantly affect its absorption. Several global randomized, controlled clinical trials have been conducted in type 1 and type 2 diabetes patients towards the clinical development of insulin tregopil. The formulation shows post-prandial glucose control that is more effective than placebo throughout the meal period; however, compared with an active comparator insulin aspart, the post-prandial control is more effective mainly in the early post-meal period. It shows a good safety profile with a lower incidence of clinically significant hypoglycemia. This review covers the overall clinical development of insulin tregopil establishing it as an ultra-fast onset, short-acting oral insulin analog for optimizing post-prandial glucose.

The Effect of BMI on Pharmacokinetic and Pharmacodynamic Parameters of Insulin Degludec: Results from an Euglycemic Glucose Clamp Study

PURPOSE

This study evaluated the effect of body mass index (BMI) on pharmacokinetic (PK) and pharmacodynamic (PD) parameters of insulin degludec in healthy Chinese males, depending on an euglycemic glucose clamp study.

METHODS

Sixty-five healthy male subjects were divided into four groups according to quartile of BMI value. Group A: BMI ≤ 20.7 kg/m²; group B: 20.7 < BMI ≤ 22.5 kg/m²; group C: 22.5 < BMI ≤ 23.6 kg/m²; group D: BMI > 23.6 kg/m². Each volunteer received a single subcutaneous dose (0.4 U/kg) of insulin degludec and accepted a 24-h euglycemic glucose clamp study. The primary PK parameters were maximum observed drug concentration (C_max) and the area under the curve (AUC_INS) for the specified time intervals. The primary PD parameters were the time to the start of glucose infusion (T_onset), maximal glucose infusion rate (GIR_max) and area under the curve (AUC_GIR) for the specified time intervals. The differences of these PK/PD parameters were compared among groups.

RESULTS

C_max and the AUC of insulin (0-6 h, 6-12 h and 0-24 h) were more than onefold higher in group A than those in groups B, C, D, and the concentration-time curve of group A was significantly shifted to the left compared with the other three groups. The GIR_max, total AUC_GIR, and AUC_GIR for each time interval were significantly higher in group A than those in other three groups. The proportion of AUC_GIR in group A was the lowest proportion among four groups seen in the late stage. Multiple linear regression analysis showed that BMI was negatively correlated with AUC_GIR,_{0-24 h}.

CONCLUSIONS

Insulin degludec in healthy Chinese male subjects with BMI ≤ 20.7 kg/m² had a faster absorption, clearance, and a stronger glucose-lowering effect, but a steeper decrease of insulin action in the late stage after dosing.

Quantitative evaluation of insulin-induced abdominal subcutaneous dystrophic tissue using shear wave elastography

Aims/Introduction

Subcutaneous dystrophic tissue (DT) produced by insulin injection causes dysglycemia owing to inadequate absorption of insulin. However, precise techniques for measuring DT have not been established. Shear wave elastography (SWE) is an imaging technology that can quantify tissue stiffness. In this study, insulin injection‐induced DT was quantified using SWE to generate whole‐abdominal wall subcutaneous tissue by three‐dimensional (3D) imaging in patients with type 2 diabetes who were treated with multiple insulin injections.

Materials and Methods

Seven patients with type 2 diabetes were recruited who received long‐standing multiple insulin injections. Using SWE, the shear wave velocity (SWV) of DT and control (normal subcutaneous tissue) was measured. Furthermore, two of seven patients underwent whole‐abdominal SWE examination to calculate the proportion of DT. A subcutaneous insulin tolerance test was also performed in both the DT and control tissues.

Results

The SWV in DT was significantly higher than that in the control tissue (2.87 [2.66–2.98] vs 1.29 [1.23–1.44] m/s, P < 0.01). The proportion of the DT volume was 0.67% and 5.21% for two individuals from the entire abdominal subcutaneous tissue volume. The area under the curve for the subcutaneously injected insulin aspart concentration at the DT sites was lower than that of the control tissue (75.0 [52.1–111] vs 116 [86.9–152.5] h*mU/L, P = 0.1).

Conclusions

SWE can be useful in quantifying abdominal subcutaneous insulin‐induced DT, especially the 3D volume of insulin injection‐induced DT from the entire abdominal subcutaneous tissue. This study is the first to examine the volume and distribution of abdominal subcutaneous DT using SWE.

Interindividual Variability in the Pharmacodynamic and Pharmacokinetic Characteristics of Recombinant Human Insulin and Insulin Aspart

PURPOSE

The present study compared the interindividual variability in the pharmacodynamic (PD) and pharmacokinetic (PK) properties of a short-acting recombinant human insulin to those of insulin aspart through manual euglycemic glucose clamp tests.

METHODS

Sixty healthy Chinese male volunteers were randomly assigned to receive human insulin or insulin aspart, administered via SC injection (0.2 U/kg). For the evaluation of interindividual variability in PD and PK properties (glucose infusion rate [GIR], insulin concentration [INS]) through euglycemic clamp studies, %CVs were calculated, and PK/PD interindividual variability was compared between the 2 groups.

FINDINGS

The differences between the human insulin and insulin aspart groups in interindividual variabilities in total AUCs of the GIR (19% vs 21%) and INS (14% vs 17%) were not significant. The interindividual variabilities in AUCgir_0-120min, early T_max50%, and AUCins_0-120min were lower in the insulin aspart group than in the human insulin group (22% vs 44%, 21% vs 35%, and 22% vs 28%, respectively; all, P ˂ 0.05), while the interindividual variabilities in the AUCs of GIR_120-600min and INS_120-600min were higher with insulin aspart than with human insulin (29% vs 20%, 51% vs 30%; both, P ˂ 0.05).

IMPLICATIONS

The overall interindividual variability with insulin aspart was similar to that with recombinant human insulin. Yet insulin concentration and metabolic effect during the declining period were more variable with insulin aspart compared to human insulin in these healthy male subjects.

A fluorescence sandwich immunoassay for the real-time continuous detection of glucose and insulin in live animals

Biosensors that continuously measure circulating biomolecules in real time could provide insights into the health status of patients and their response to therapeutics. But biosensors for the continuous real-time monitoring of analytes in vivo have only reached nanomolar sensitivity and can measure only a handful of molecules, such as glucose and blood oxygen. Here we show that multiple analytes can be continuously and simultaneously measured with picomolar sensitivity and sub-second resolution via the integration of aptamers and antibodies into a bead-based fluorescence sandwich immunoassay implemented in a custom microfluidic chip. After an incubation time of 30 s, bead fluorescence is measured using a high-speed camera under spatially multiplexed two-colour laser illumination. We used the assay for continuous quantification of glucose and insulin concentrations in the blood of live diabetic rats to resolve inter-animal differences in the pharmacokinetic response to insulin as well as discriminate pharmacokinetic profiles from different insulin formulations. The assay can be readily modified to continuously and simultaneously measure other blood analytes in vivo.

Optimal Design of Needle Array for Effective Drug Delivery

Recently, the multi-needle drug injection has been adopted to overcome the shortcomes of conventional single-needle injection, enhancing the efficiency of drug delivery. However, the effect of needle array on the efficacy of drug delivery has not been fully elucidated. In this study, the interactions of drug analogous solution injected from a pair of needles were analyzed to examine the design criteria of effective multi-needle devices for drug delivery. Temporal and spatial variations of relative contents of the solution in the tissues were compared according to the distance between two adjacent needles (DN). As the DN increases from 5 to 20 D, where D is the needle diameter, the solution from each needle encounters 3.5 times faster, and 4.22 times more solution was accumulated. At the same time, the effective spreading area was continuously increased from 54.2 to 177.8 mm² and RCS gradient decreases from 0.087 to 0.037, due to the overlapping effect of the spreading solution from neighboring needles. Finally, based on the experimental results, an optimal design criterion of needle array for effective drug delivery was proposed. The present results would be helpful in the design of multi-needle injection devices and eventually offer advantage to patients with effective drug delivery.

Factors Affecting the Absorption of Subcutaneously Administered Insulin: Effect on Variability

Variability in the effect of subcutaneously administered insulin represents a major challenge in insulin therapy where precise dosing is required in order to achieve targeted glucose levels. Since this variability is largely influenced by the absorption of insulin, a deeper understanding of the factors affecting the absorption of insulin from the subcutaneous tissue is necessary in order to improve glycaemic control and the long-term prognosis in people with diabetes. These factors can be related to either the insulin preparation, the injection site/patient, or the injection technique. This review highlights the factors affecting insulin absorption with special attention on the physiological factors at the injection site. In addition, it also provides a detailed description of the insulin absorption process and the various modifications to this process that have been utilized by the different insulin preparations available.

Effective method for drug injection into subcutaneous tissue

Subcutaneous injection of drug solution is widely used for continuous and low dose drug treatment. Although the drug injections have been administered for a long time, challenges in the design of injection devices are still needed to minimize the variability, pain, or skin disorder by repeated drug injections. To avoid these adverse effects, systematic study on the effects of injection conditions should be conducted to improve the predictability of drug effect. Here, the effects of injection conditions on the drug permeation in tissues were investigated using X-ray imaging technique which provides real-time images of drug permeation with high spatial resolution. The shape and concentration distribution of the injected drug solution in the porcine subcutaneous and muscle tissues are visualized. Dynamic movements of the wetting front (WF) and temporal variations of water contents in the two tissues are quantitatively analyzed. Based on the quantitative analysis of the experimental data, the permeability of drug solution through the tissues are estimated according to permeation direction, injection speed, and tissue. The present results would be helpful for improving the performance of drug injection devices and for predicting the drug efficacy in tissues using biomedical simulation.

Oral Insulin Delivery in a Physiologic Context: Review

Insulin remains indispensable to the treatment of diabetes, but its availability in injectable form only has hampered its timely and broader use. The development of an oral insulin remains an ultimate goal to both enhance ease of use, and to provide therapeutic advantages rooted in its direct delivery to the portal vein and liver. By mimicking the physiological path taken by pancreatic insulin, oral insulin is expected to have a distinct effect on the hepatic aspect of carbohydrate metabolism, hepatic insulin resistance, and, at the same time, avoid hyperinsulinemia and minimize the risk of hypoglycemia. With oral insulin approaching late stages of development, the goal of this review is to examine oral insulin in a physiological context and report on recent progress in its development.

Improving drug-like properties of insulin and GLP-1 via molecule design and formulation and improving diabetes management with device & drug delivery

There is an increased incidence of diabetes worldwide. The discovery of insulin revolutionized the management of diabetes, the revelation of glucagon-like peptide-1 (GLP-1) and introduction of GLP-1 receptor agonists to clinical practice was another breakthrough. Continued translational research resulted in better understanding of diabetes, which, in combination with cutting-edge biology, chemistry, and pharmaceutical tools, have allowed for the development of safer, more effective and convenient insulins and GLP-1. Advances in self-administration of insulin and GLP-1 receptor agonist therapies with use of drug-device combination products have further improved the outcomes of diabetes management and quality of life for diabetic patients. The synergies of insulin and GLP-1 receptor agonist actions have led to development of devices that can deliver both molecules simultaneously. New chimeric GLP-1-incretins and insulin-GLP-1-incretin molecules are also being developed. The objective of this review is to summarize molecular designs to improve the drug-like properties of insulin and GLP-1 and to highlight the continued advancement of drug-device combination products to improve diabetes management.

Examining Factors That Impact Inpatient Management of Diabetes and the Role of Insulin Pen Devices

Insulin administration in the acute care setting is an integral component of inpatient diabetes management. Although some institutions have moved to insulin pen devices, many acute care settings continue to employ the vial and syringe method of insulin administration. The aim of this study was to evaluate the impact of insulin pen implementation in the acute care setting on patients, healthcare workers and health resource utilization. A review of published literature, including guidelines, was conducted to identify how insulin pen devices in the acute care setting may impact inpatient diabetes management. Previously published studies have revealed that insulin pen devices have the potential to improve inpatient management through better glycemic control, increased adherence and improved self-management education. Furthermore, insulin pen devices may result in cost savings and improved safety for healthcare workers. There are benefits to the use of insulin pen devices in acute care and, as such, their implementation should be considered.

Spatial distribution of soluble insulin in pig subcutaneous tissue: Effect of needle length, injection speed and injected volume

The spatial distribution of a soluble insulin formulation was visualized and quantified in 3-dimensions using X-ray computed tomography. The drug distribution was visualized for ex vivo injections in pig subcutaneous tissue. Pig subcutaneous tissue has very distinct layers, which could be separated in the tomographic reconstructions and the amount of drug in each tissue class was quantified. With a scan time of about 45min per sample, and a robust segmentation it was possible to analyze differences in the spatial drug distribution between several similar injections. It was studied how the drug distribution was effected by needle length, injection speed and injected volume. For an injected volume of 0.1ml and injection depth of 8mm about 50% of the injections were partly intramuscular. Using a 5mm needle resulted in purely subcutaneous injections with minor differences in the spatial drug distribution between injections. Increasing the injected volume from 0.1ml to 1ml did not increase the intramuscular volume fraction, but gave a significantly higher volume fraction placed in the fascia separating the deep and superficial subcutaneous fat layers. Varying the injection speed from 25l/s up to 300l/s gave no changes in the drug concentration distribution. The method presented gives novel insight into subcutaneous injections of soluble insulin drugs and can be used to optimize the injection technique for subcutaneous drug administration in preclinical studies of rodents.

Variability of glucose-lowering effect as a limiting factor in optimizing basal insulin therapy: a review

Lowering blood glucose with insulin therapy towards beneficial target levels while also avoiding hypoglycaemia is a challenging task. An important confounding factor, which might be under-appreciated in this scenario, is that of variable glucose readings causing difficulties with dose adjustment. Furthermore, this glucose variability is, to some extent, a reflection of variability in the glucose-lowering action of the insulin therapy itself. Not only is glucose variability a major confounding factor in disease management but it is possibly also of direct prognostic consequence and is increasingly recognized as an informative measurement in diabetes management. The scope for insulin-induced glucose variability is particularly great with basal insulins because of their prolonged absorption from high-dose depots. Pharmacodynamic (PD) variability manifests as both fluctuations in the level of glucose-lowering effect over time, and as inconsistencies in the response from one injection to another. Well-controlled pharmacokinetic (PK)/PD studies using repeated isoglycaemic clamp methodology clearly how that many injected basal insulin products have high variable absorption with correspondingly variable action. Incomplete resuspension and precipitation appear to be important issues with regard to unpredictability in this action, while an inadequate duration of action relative to the dosing interval results in a fluctuating action profile. There are some ultra-long-acting basal insulins with novel protraction mechanisms currently in clinical development for which clamp studies show markedly improved PK/PD profiles.

Forum for injection techniques, India: the first Indian recommendations for best practice in insulin injection technique

Advances in the treatment of diabetes have led to an increase in the number of injectable therapies, such as human insulin, insulin analogues, and glucagon-like peptide-1 analogues. The efficacy of injection therapy in diabetes depends on correct injection technique, among many other factors. Good injection technique is vital in achieving glycemic control and thus preventing complications of diabetes. From the patients' and health-care providers' perspective, it is essential to have guidelines to understand injections and injection techniques. The abridged version of the First Indian Insulin Injection technique guidelines developed by the Forum for Injection Technique (FIT) India presented here acknowledge good insulin injection techniques and provide evidence-based recommendations to assist diabetes care providers in improving their clinical practice.

Pharmacokinetics and pharmacodynamics of insulin analogs in special populations with type 2 diabetes mellitus

Introduction

The goal of insulin therapy in patients with either type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM) is to match as closely as possible normal physiologic insulin secretion to control fasting and postprandial plasma glucose. Modifications of the insulin molecule have resulted in two long-acting insulin analogs (glargine and detemir) and three rapid-acting insulins (aspart, lispro, and glulisine) with improved pharmacokinetic/pharmacodynamic (PK/PD) profiles. These agents can be used together in basal-bolus therapy to more closely mimic physiologic insulin secretion patterns.

Methods

This study reviews effects of the multiple demographic and clinical parameters in the insulin analogs glargine, detemir, lispro, aspart, and glulisine in patients with T2DM. A search was conducted on PubMed for each major topic considered (effects of injection site, age, race/ethnicity, obesity, renal or hepatic dysfunction, pregnancy, exercise, drug interactions) using the topic words and name of each type of insulin analog. Information was also obtained from the prescribing information for each insulin analog.

Results

The PK/PD profiles for insulin analogs may be influenced by many variables including age, weight, and hepatic and renal function. However, these variables do not have equivalent effects on all long-acting or rapid-acting insulin analogs.

Conclusion

Rapid-acting and long-acting insulin analogs represent major advances in treatment for patients with T2DM who require insulin therapy. However, there are potentially important PK and PD differences between the two long-acting agents and among the three rapid-acting insulin analogs, which should be considered when designing treatment regimens for special patient groups.

Non-inferiority of insulin glargine versus insulin detemir on blood glucose variability in type 1 diabetes patients: a multicenter, randomized, crossover study

BACKGROUND

This study compared the effects of insulin glargine and insulin detemir on blood glucose variability under clinical practice conditions in patients with type 1 diabetes (T1D) using glulisine as the mealtime insulin.

METHODS

This was a multicenter, crossover trial in 88 randomized T1D patients: 54 men and 34 women, 46.8±13.7 years old, with a duration of diabetes of 18±9 years and hemoglobin A1c level of 7.1±0.7%. The per-protocol population included 78 patients: 44 received glargine/detemir and 34 detemir/glargine in the first/second 16-week period, respectively. The primary end point was the coefficient of variation (CV) of fasting blood glucose (FBG). Secondary end points included variability of pre-dinner blood glucose, mean amplitude of glycemic excursions, mean of daily differences, and doses and number of daily insulin injections. The non-inferiority criterion was an insulin glargine/insulin detemir FBG CV ratio with a 95% confidence interval (CI) upper limit ≤1.25.

RESULTS

The non-inferiority criterion was satisfied with a mean value of 1.016 (95% CI=0.970-1.065). Intention-to-treat analysis confirmed the non-inferiority with a 95% CI upper limit=1.062. No significant differences were found on secondary objectives, but there was a trend to higher doses and number of daily injections with insulin detemir. A total of eight (four glargine and four detemir) patients reported nine serious adverse events (including one severe episode of hypoglycemia). None of them was considered as related to basal insulins. Serious adverse events led to treatment discontinuation in two patients of the detemir group and none in the glargine group.

CONCLUSIONS

In T1D patients under clinical practice conditions, insulin glargine was non-inferior to insulin detemir regarding blood glucose variability, as assessed by CV of FBG.

Insulin administration: selecting the appropriate needle and individualizing the injection technique

INTRODUCTION

Patients with diabetes who receive insulin therapy often fail to meet their targets for metabolic control with insulin injections. Their inadequate glycemic control may be related to incorrect injection procedure.

AREAS COVERED

This review examines the latest data related to insulin injection and needle characteristics, which play an integral role in patient satisfaction. Searches of Medline and Cumulative Index to Nursing and Allied Health Literature databases were conducted. Results show that optimal insulin injection can facilitate glycemic control in pediatric and adult patients. In general, needles shorter than 8 mm are appropriate for normal weight, obese pediatric and adult patients. However, body mass index, gender, race, age and injection site can influence the depth of subcutaneous tissue and thus, the desired needle size and injection technique. Although the abdomen, thighs and buttocks are all recommended injection sites, abdominal injections disperse insulin slightly more rapidly than thigh injections.

EXPERT OPINION

Wider acceptance of needles shorter than 6 mm will occur with more evidence of their safety and efficacy, particularly in children. Development of shorter and thinner needles to make injections even easier and less burdensome may be expected in the future.

Metabolic consequences of incorrect insulin administration techniques in aging subjects with diabetes

Only few insulin-treated (IT) people with diabetes mellitus (DM) reach the target due to poor compliance and/or to sedentary lifestyle and/or to inadequate treatment regimen. The latter may be also brought about by often overlooked factors including insulin injection into altered skin areas, often brought about by incorrect habits, namely needle reutilization or poor compliance to the suggestion to continuously rotate skin injection areas. The aim of our study was to evaluate the rate of skin lesions within the sites commonly used for insulin injection in our IT DM patients and to verify whether a short-acting insulin analogue yielded different metabolic effects when injected in altered vs. normal skin areas. One hundred and eighty well-trained IT people with type 1 and type 2 DM (64 ± 15 years of age) consecutively referring to our unit underwent a standard clinical examination involving an accurate skin inspection protocol meant at looking for any alterations eventually affecting all possible injection sites, including bruising, multiple needle pricks and lipodystrophic nodules (LN). They were also tested for HPLC HbA1c determination and asked to fill in a standard questionnaire on injection habits. Furthermore, seven male, T1DM glulisine-glargine basal-bolus-treated patients in this group were randomly injected 10 IU glulisine into either normal skin (NS) or an LN by a nurse before a standard, 405 kcal breakfast, for blood glucose and free insulin determination at 0, 30, 45, 60, 75, 90, 120 and 150 min. More lesions were found in people over sixty (P < 0.01) and in women (P < 0.05). A higher prevalence of HbA1c >7.5% was found in patients with lesions (with an O.R. of 3.74) and further confirmed by data obtained from head-to-head comparison of insulin injection into an LN and NS. In fact, injection into an LN proved to impair and slow down insulin absorption, resulting in a higher absolute value and a larger variability of blood glucose levels than those observed by utilizing NS. This suggests us to pay more attention to all aspects of patient-team relationship to try and obtain good metabolic control in all people with diabetes and even more in the elderly.

Differences between long-acting insulins for the treatment of type 2 diabetes

IMPORTANCE OF THE FIELD

Most guidelines suggest that failure of oral antidiabetic drugs should be followed by the addition of a basal insulin with aggressive titration of the dose. In most countries, neutral protamine Hagedorn (NPH)-insulin, glargine and detemir are the only choices. Clinical trials show that the metabolism and metabolic outcomes after treatment with intermediate- or long-acting insulins differ little. Despite this, the hypoglycaemic potential, effect on body weight and adherence to insulin treatment may affect the choice of basal insulin. Adherence seems to be negatively correlated to the prescribed dose and the number of injections. Furthermore, the choice of basal insulin might be influenced by the number of units necessary to achieve the goal for HbA1c.

AREAS COVERED IN THIS REVIEW

By searching the literature systematically, we identified all randomised clinical trials comparing long-acting insulins (human NPH-insulin and the analogues glargine and detemir) for the treatment of type 2 diabetes conducted over the last 10 years. We continued by reviewing only studies in which similar antihyperglycaemic potential of the treatments was achieved.

WHAT THE READER WILL GAIN

According to the inclusion criteria for this review, all drugs were efficacious regarding the main purpose of decreasing glycaemia. For an equal efficacy, we were able to detect other differences between the treatments and, furthermore, an estimate on the number of units of insulin needed to achieve comparable glycaemic control.

TAKE HOME MESSAGE

The analysis confirmed a favourable profile of both analogues regarding hypoglycaemia. For detemir, we additionally identified a favourable profile regarding weight gain and need for an increased number of units of insulin to achieve comparable glycosylated haemoglobin (HbA1c) responses. We conclude that the efficacy of insulin treatment seems to vary little between the available products, however doses needed to achieve similar effects vary; units used per HbA1c reduction could be a relevant parameter for the choice of insulin.

How pharmacokinetic and pharmacodynamic principles pave the way for optimal basal insulin therapy in type 2 diabetes

This pedagogical review illustrates the differences between pharmacokinetic (PK) and pharmacodynamic (PD) measures, using insulin therapy as the primary example. The main conclusion is that PD parameters are of greater clinical significance for insulin therapy than PK parameters. The glucose-clamp technique, the optimal method for determining insulin PD, is explained so that the reader can understand the important studies in the literature. Key glucose-clamp studies that compare two basal insulin analogues - insulin glargine and insulin detemir - to Neutral Protamine Hagedorn insulin and to each other are then presented. The review further explains how PD parameters have been translated into useful clinical concepts and simple titration algorithms for everyday clinical practice. Finally, the necessity of overcoming patient and/or physician barriers to insulin therapy and providing continuing education and training is emphasised.

An analysis of the mixing efficiency of neutral protamine Hagedorn cartridges

In this issue of Journal of Diabetes Science and Technology, Kaiser and colleagues conducted an investigation to identify variations in the delivered dose of several different isophane insulin (neutral protamine Hagedorn, NPH) brands that use glass and metal bodies ("bullets") to facilitate mixing. Using a strategy where multiple pens from each of five different NPH insulin products (Insuman Basal, sanofi-aventis, three metal bullets; Humulin N, Lilly, one glass bullet; Berlinsulin H Basal, Berlin-Chemie, one glass bullet; Insulin B. Braun Basal, two glass bullets; and Protaphane Penfill, NovoNordisk, one glass bullet) were compared at multiple sampling points and over a range of mixing procedures (3, 6, 10, and 20 times), the authors identified deviations in the delivered dose of insulin at initial use and with repeated dosing. At the initial dose, adhering with manufacturer recommendations to conduct the mixing procedure 10-20 times was found to demonstrate minimal deviation and there was no pronounced difference among the products. Decreasing the number of mixing procedures from 10-20 to 3-6 times, a more profound deviation was noted, with the Insuman Basal product demonstrating less variability in comparison to all other products evaluated. A repeated dose study (1, 2, 6, and 10) with only six mixing procedures revealed that the insulin concentration of each dose increased for all products except Insuman Basal. Clinically, numerous factors may contribute to variability observed with subcutaneous administration of isophane insulin. While data presented by Kaiser and colleagues demonstrated that the issue of proper mixing is not trivial, the modest differences observed between and within products both at the initial dose and with repeated dosing may indicate that the clinical relevance of these findings is most applicable to those requiring large doses or, alternatively, those who have otherwise unexplained hypoglycemic episodes.

Microneedle-based intradermal delivery enables rapid lymphatic uptake and distribution of protein drugs

PURPOSE

The purpose of this research was to examine the pharmacokinetics (PK) of drug uptake for microneedle-based intradermal (ID) delivery of several classes of protein drugs compared to standard subcutaneous (SC) administration.

METHODS

Systemic absorption kinetics of various proteins were analyzed following microneedle-based ID delivery and standard injection methods in the swine model. Comparative PK data were determined using standard non-compartmental techniques based on blood serum levels.

RESULTS

Delivery of proteins using microneedles resulted in faster systemic availability, measured via t(max,) and increased maximal drug concentration, C(max,) over SC delivery for all proteins tested. Some agents also exhibited increased bioavailability for the ID route. Imaging studies using reporter dyes showed rapid lymphatic-mediated uptake.

CONCLUSIONS

Microneedle delivery is applicable to a wide variety of protein drugs and is capable of effective parenteral administration of therapeutic drug dosages. This delivery route alters absorption kinetics via targeting a tissue bed better perfused with lymphatic and blood vessels than the SC space. Microneedle delivery may afford various advantages, including a robust method to increase the absorption rate and bioavailability of proteins that have been challenging to deliver at therapeutic levels or with physiologically relevant profiles.

Management of progressive type 2 diabetes: role of insulin therapy

Insulin is an effective treatment for achieving tight glycemic control and improving clinical outcomes in patients with diabetes. While insulin therapy is required from the onset of diagnosis in type 1 disease, its role in type 2 diabetes requires consideration as to when to initiate and advance therapy. In this article, we review a case study that unfolds over 5 years and discuss the therapeutic decision points, initiation and advancement of insulin regimens, and analyze new data regarding the advantages and disadvantages of tight management of glucose levels.

A subcutaneous insulin pharmacokinetic model for computer simulation in a diabetes decision support role: model structure and parameter identification

OBJECTIVE

The goal of this study was to develop a unified physiological subcutaneous (SC) insulin absorption model for computer simulation in a clinical diabetes decision support role. The model must model the plasma insulin appearance of a wide range of current insulins, especially monomer insulin and insulin glargine, utilizing common chemical states and transport rates, where appropriate.

METHODS

A compartmental model was developed with 13 patient-specific model parameters covering six diverse insulin types [rapid-acting, regular, neutral protamine Hagedorn (NPH), lente, ultralente, and glargine insulin]. Model parameters were identified using 37 sets of mean plasma insulin time-course data from an extensive literature review via nonlinear optimization methods.

RESULTS

All fitted parameters have a coefficient of variation <100% (median 51.3%, 95th percentile 3.6-60.6%) and can be considered a posteriori identifiable.

CONCLUSION

A model is presented to describe SC injected insulin appearance in plasma in a diabetes decision support role. Clinically current insulin types (monomeric insulin, regular insulin, NPH, insulin, and glargine) and older insulin types (lente and ultralente) are included in a unified framework that accounts for nonlinear concentration and dose dependency. Future work requires clinical validation using published pharmacokinetic studies.

Impact of therapeutic advances on hypoglycaemia in type 2 diabetes

Patients with type 2 diabetes experience hypoglycaemia less frequently than those with type 1 diabetes. Some protection against hypoglycaemia is afforded by the relatively intact glucose counter-regulatory pathways that characterize the pathophysiology of early type 2 diabetes. To some extent, this protection explains why hypoglycaemic episodes in intensively treated individuals with type 2 diabetes, when they occur, are rarely severe. As diabetes progresses and therapy intensifies to achieve recommended glycaemic goals, hypoglycaemia frequency and severity increase. Thus, when it comes to instituting intensive therapy, fear of hypoglycaemia may contribute to health-care providers' 'clinical inertia'. Because maintaining glycaemic control is so important to both public and individual health, many new therapies and technologies have been developed. This manuscript reviews and considers whether these advancements in therapy make glycaemic goals easier to achieve by minimizing hypoglycaemia. Putting the hypoglycaemia experienced by type 2 diabetes patients into appropriate clinical perspective, the impact of recent progress made in pharmacotherapy, drug delivery systems, and BG monitoring on hypoglycaemia incidence is largely positive. The extent to which this progress can effect improvement over traditional therapies will, however, depend upon patient (and provider) education, motivation and behaviour change.

[Insulin therapy for type 1 diabetes mellitus: past and present]

The discovery of insulin can be considered the milestone of diabetes mellitus history and a great achievement for its treatment. The first insulin available was the regular. Afterwards, Hagedorn added the protamine to the insulin, thus, creating the NPH insulin. In the 1950s an insulin free of protamine was synthesized: the lente insulin. With the advent of molecular biology, synthetic human insulin was synthesized using recombinant DNA technology. Most recently several types of insulin analogues were available, providing the patients with better metabolic control. Type 1 diabetes mellitus treatment includes plain substitution and individualization for short-acting plus long-acting insulin according to the physician's assistance, besides regular practice of physical activities and diet orientations. In type 1 diabetes mellitus the insulin of low variability is the best choice since basal/bolus insulin therapy or continuous subcutaneous insulin infusion pump can mimetize the physiological release of insulin by beta cells.

Inhaled Technosphere insulin in comparison to subcutaneous regular human insulin: time action profile and variability in subjects with type 2 diabetes

BACKGROUND

This study assessed time action profile and within- and between-subject variability of inhaled Technosphere Insulin (TI) compared with subcutaneous regular human insulin (sc RHI).

METHODS

Thirteen subjects with type 2 diabetes (age 56 +/- 7 years, body mass index 30.4 +/- 3.0 kg.m(-2); hemoglobin A1c 6.9 +/- 0.9%; mean +/- SD) participated in this six-period crossover isoglycemic glucose clamp study. In randomized order, each subject received three single doses of TI and sc RHI on separate study days.

RESULTS

Inhalation of TI resulted in a higher maximum serum insulin concentration (858 vs 438 pmol.liter(-1); p = 0.0001) and shorter intervals to maximum insulin concentration (17 vs 135 minutes; p = 0.0001) than sc RHI. Overall, 48 units of TI and 24 units of sc RHI provided comparable 3-hour insulin exposure (INS area under the curve(0-3 h) 55.8 vs 60.0 nmol.min.liter(-1), respectively). Time to maximum metabolic effect was shorter (79 vs 293 minutes; p < 0.0001), and percentage of glucose disposal during the first 3 hours was higher for TI compared with sc RHI (59 vs 27%). Within-subject variabilities of insulin exposure following inhalation of TI for 2 and 3 hours and end of study period were 19, 18, and 16% as compared with 27, 25, and 15% after sc RHI injection (p = not significant).

CONCLUSION

Technosphere Insulin has a more rapid onset of action than sc RHI. About 60% of the glucose-lowering effect of TI occurs during the first 3 hours after application. In contrast, <30% of the glucose-lowering effect of sc RHI occurs in this period. Technosphere Insulin demonstrated a lower intrasubject variability during the 3-hour postprandial period, without reaching statistical significance.

Defining the role of insulin detemir in Basal insulin therapy

Insulin detemir is a novel long-acting insulin analogue with a unique mechanism underlying its prolonged duration of action. Unlike neutral protamine Hagedorn (NPH) insulin (insulin suspension isophane) and insulin glargine, which precipitate after administration, insulin detemir remains soluble after it is injected. The prolonged duration of action of insulin detemir is a result of the ability to self-associate into hexamers and dihexamers, and to bind reversibly to albumin. This mechanism of protraction provides a more prolonged, consistent and predictable glycaemic effect in patients with type 1 or type 2 diabetes mellitus compared with NPH insulin. Clinical studies have demonstrated that insulin detemir administered once or twice daily is at least as effective as NPH insulin and insulin glargine in achieving glycaemic control. Most trials have also shown that insulin detemir exhibits less intrapatient variability in glycaemic control compared with NPH insulin and insulin glargine. One of the benefits of insulin detemir is its favourable effect on bodyweight. Insulin detemir has shown weight neutrality in patients with type 1 diabetes and is associated with less weight gain than NPH insulin in clinical studies. Patients with type 2 diabetes using insulin detemir gain less weight than patients using NPH insulin and insulin glargine. In addition, a reduced risk of hypoglycaemia, particularly nocturnal hypoglycaemia, has been reported with insulin detemir compared with NPH insulin in patients with type 1 and type 2 diabetes. A reduced risk of major and nocturnal hypoglycaemia compared with insulin glargine in patients with type 1 diabetes has also been observed. Together, these data indicate that insulin detemir is a valuable new option for basal insulin therapy in patients with type 1 or type 2 diabetes.

Insulin therapy in diabetes mellitus: how can the currently available injectable insulins be most prudently and efficaciously utilised?

The era of animal source insulins has passed and human recombinant DNA insulins are gradually being replaced because of the superior efficacy of insulin analogues. Analogue insulins are available in both rapid- and long-acting preparations. Currently available rapid-acting insulins are lispro, aspart and glulisine, and the currently available long-acting analogue basal insulins are detemir and glargine. The rapid-acting insulin analogues are also available in combination with protamine in fixed-dose pre-mixed insulins to provide a more sustained action. The chemical structure, subcutaneous behaviour, time of onset, maximal effect and duration of action of both analogue and human insulins, and how these actions can be best utilised in the diabetic patient are discussed in this review. In addition, strategies where efficacy of the available analogue insulins can be maximally utilised in both type 1 and type 2 diabetes mellitus are described. Maximal utilisation of analogue insulins will result not only in better glycaemic control, but will also minimise the frequency and severity of hypoglycaemic episodes. In addition, maximisation of glycaemic control will result in prevention, delay of onset or amelioration of both the microvascular and perhaps the macrovascular complications of diabetes.

Technosphere insulin technology

The ideal prandial insulin would possess characteristics of the insulin response profile seen in healthy individuals without diabetes. Approximating the early-phase insulin response that is lost in diabetes is challenging for injected insulins, especially achieving rapid insulin absorption and a favorable duration of metabolic effect. Technosphere (MannKind Corp., Valencia, CA) inhalation powder is a novel delivery platform that enables large peptides to be delivered via the pulmonary route. Technosphere Insulin (TI), a formulation of regular human insulin, has been specifically designed to facilitate efficient transport via the inhaled route. TI is rapidly absorbed (time to maximum effect of approximately 15 min) and has a rapid onset of action. The metabolic effect of TI peaks approximately 1 h after administration, substantially earlier than what has been reported for other insulins. The majority of the glucose-lowering activity of TI is delivered in the first 3 h. In preliminary studies, TI was well tolerated. Phase 3 studies are under way to evaluate the long-term efficacy and safety of TI in patients with type 1 and type 2 diabetes.

The treat-to-target A1C approach to control type 2 diabetes and prevent complications

Before initiating insulin therapy, clinicians often wait until oral antidiabetic agents fail to adequately reduce glycosylated hemoglobin (A1C) levels and control hyperglycemia in patients with type 2 diabetes. Long-term, randomized clinical trials demonstrate that reducing A1C to close to normal decreases rates of microvascular complications and can also reduce macrovascular complications. Insulin regimens that treat to target A1C levels may achieve greater control of hyperglycemia. Various randomized trials have assessed the efficacy and safety of initiating insulin therapy with human insulins and insulin analogs in patients with type 2 diabetes whose condition is inadequately controlled with oral antidiabetics. These studies assessed different regimens, including basal and premixed insulins, for their ability to reach target A1C goals and provided evidence-based protocols for the initiation and systematic dosage titration of insulin therapy in patients with type 2 diabetes. Examples of how to initiate and intensify insulin therapy to achieve target A1C goals based on these protocols are presented.

pI-shifted insulin analogs with extended in vivo time action and favorable receptor selectivity

A long-acting (basal) insulin capable of delivering flat, sustained, reproducible glycemic control with once daily administration represents an improvement in the treatment paradigm for both type 1 and type 2 diabetes. Optimization of insulin pharmacodynamics is achievable through structural modification, but often at the expense of alterations in receptor affinity and selectivity. A series of isoelectric point (pI)-shifted insulin analogs based on the human insulin sequence or the GlyA21 acid stable variant were prepared by semi-synthetic methods. The pI shift was achieved through systematic addition of one or more arginine (Arg) or lysine (Lys) residues at the N terminus of the A chain, the N terminus of the B chain, the C terminus of the B chain, or through a combination of additions at two of the three sites. The analogs were evaluated for their affinity for the insulin and IGF-1 receptors, and aqueous solubility under physiological pH conditions. Notably, the presence of positively charged amino acid residues at the N terminus of the A chain was consistently associated with an enhanced insulin to IGF-1 receptor selectivity profile. Increased IGF-1 receptor affinity that results from Arg addition to the C terminus of the B chain was attenuated by cationic extension at the N terminus of the A chain. Analogs 10, 17, and 18 displayed in vitro receptor selectivity similar to that of native insulin and solubility at physiological pH that suggested the potential for extended time action. Accordingly, the in vivo pharmacokinetic and pharmacodynamic profiles of these analogs were established in a somatostatin-induced diabetic dog model. Analog 18 (A0:Arg, A21:Gly, B31:Arg, B32:Arg human insulin) exhibited a pharmacological profile comparable to that of analog 15 (insulin glargine) but with a 4.5-fold more favorable insulin:IGF-1 receptor selectivity. These results demonstrate that the selective combination of positive charge to the N terminus of the A chain and the C terminus of the B chain generates an insulin with sustained pharmacology and a near-native receptor selectivity profile.

Diabetes: the latest trends in glycemic control

The increasing pervasiveness of diabetes mellitus on a global stage has been well documented. Many groundbreaking studies have detailed the consequences of inadequate glycemic control, but only recently have data supported evidence that demonstrates benefits in the acute setting. Consensus is lacking with regard to how to achieve glycemic control in the hospital setting. This article discusses glycemic control, with special emphasis on the perioperative patient. Emerging therapeutic treatments and less frequently encountered protocols such as insulin pump management and insulin infusion are considered.

Glargine blood biotransformation: in vitro appraisal with human insulin immunoassay

AIM

Glargine, a long-acting insulin analogue, is metabolized in the bloodstream and in subcutaneous tissue. Glargine metabolism and its implications for diabetes therapy remain poorly understood. The aim of our study was to assess in vitro the glargine blood biotransformation and its inter-individual variability.

METHODS

Formation of M1 glargine metabolite in vitro was studied with Elecsys Insulin immunoassay in pools of sera and sera from patients spiked with glargine. Elecsys Insulin assay is specific of human insulin, does not recognize glargine and its M2 metabolite but does recognize its M1 metabolite.

RESULTS

Glargine incubation with serum resulted in M1 metabolite formation which was detected and characterized as an enzymatic process: metabolite kinetics were dependant on temperature, substrate concentration and serum proportion. Carboxypeptidase inhibitors and chelating agents partially inhibited the activity of the enzyme(s). Glargine biotransformation was decreased when blood was collected on EDTA tubes. After 30 min incubation of glargine (100 mU/l) in 69 sera at 37 degrees C, percentage of glargine converted into M1 ranged from 46% to 98% (mean 72%; S.D. 11%).

CONCLUSION

Glargine blood biotransformation is an enzymatic process probably involving serum carboxypeptidase(s). Metabolite formation is rapid and non negligible. Inter-individual variability of glargine biotransformation is noteworthy and should be confronted to M1 metabolite bioactivity which has not been fully documented yet.

Subcutaneous insulin: pharmacokinetic variability and glycemic variability

The therapeutic goal in insulin-treated diabetic patients is to maintain on the long-term a tight glucose control (HbA1, < 6.5-7% or less) through an insulin regimen which "mimic" the physiological insulin profile: a basal insulin secretion to maintain glucose homeostasis and an acute post-prandial secretion in response to meal intake. Such goal represents a challenge for the clinician as conventional human insulins have major drawbacks: slow absorption and too late peak with regular insulins, delayed peak and often occuring at an unwanted time with intermediate and long-acting insulins. Furthermore, these insulins are characterised by a large within- and between-subjects variability, which complicate patients' task to self-adapt their daily doses, even for those well educated and compliants. These limitations and unpredictable variations in insulin action are responsible for an increased risk of hypoglycemic events, between meals as well as during the night period. As a consequence, glucose control is frequently insufficient in type 1 diabetic patients, and these limitations may contribute also to the delayed initiation of insulin therapy in type 2 diabetics when oral antidiabetic agents fail. This variability and the non-reproducibility of the conventional insulin pharmacodynamics are explained by several exogenous and endogenous factors describe in this review. Availability of new short-acting (lispro, aspart and glulisine) and long-acting analogs (glargine, detemir) of human insulin, with improved pharmacokinetic characteristics, and a lesser variability and better reproducibility, should facilitate a tight glucose control in insulin-treated patients. The main pharmacokinetic and pharmacodynamic characteristics of these new insulin analogs are presented and discussed in the light of there intra- and inter-individual variability. Their reduced variability should permit to reinforce near "physiological" insulin regimen such as "basal-bolus" technique and to consider new approaches and therapeutic strategies in type 1 and type 2 diabetic patients.

Limitations of the so-called "intensified" insulin therapy in type 1 diabetes mellitus

Intensive insulin treatment is defined by basal-prandial insulin therapy which tries to reproduce physiological insulin secretion. This requires 3 to 5 injections and self-monitoring of blood glucose 4 to 5 times a day. Patients who accept their disease and the demanding treatment regimen most often achieve HbA1(c) < 7.5%. Severe complications of diabetes can be avoided without increasing the risk of severe hypoglycemia. However, 50% of type 1 diabetic patients do not reach this objective. The reasons are: the disease itself, the diabetic patient, or the physician. Brittle diabetes with severe, repeated episodes of hypoglycemia and inversely persistent postprandial hyperglycemia prevents patients from reaching the ideal glycemic target. More often, the main obstacle is related to psychological problems: difficulties in self-regulation, denial of the disease, or phobia of hypoglycemia with avoidance behavior. Frequently, young women present eating disorders which can explain the poor diabetes control. The physician himself may be implicated in these poor glycemic results by not prescribing the right tools to obtain optimal glycemic control (staying with just two daily injections with premixed insulin) or by assigning glycemic targets inaccessible for the patient, or when an empathic relationship cannot be established between the patient and the physician. Patient empowerment is the key to the success of functional insulin treatment.

Is insulin detemir able to favor a lower variability in the action of injected insulin in diabetic subjects?

Insulin treated diabetic patients have often to contend with variability in the action of injected insulin and to some unpredictibility in glycemic control. The variability in blood glucose control seems particularly important with long-acting insulins. Insulin detemir belongs to a new class of non-crystalline form of long-acting insulin analogs. Absorption of insulin detemir is dependent on neither appropriate resuspension before injection and dissolution of crystals in the subcutaneous tissue, as is the case for NPH insulin, nor on formation and dissolution of microprecipitates, as is the case for insulin glargine. In euglycemic glucose clamp studies, insulin detemir was associated with significantly less within-subjects variability for the pharmacodynamic endpoints than both NPH insulin and insulin glargine. Three, up to 6 months trials, carried out in patients with type 1 diabetes have shown that the day-to-day within-subject variations in plasma glucose were significantly lower with insulin detemir than with human NPH insulin. Similar results have been reported in patients with type 2 diabetes. Nightly 8-h plasma glucose recordings showed a smoother and more stable profile with insulin detemir than with NPH insulin. In patients with type 1 diabetes the combination of insulin detemir with mealtime insulin aspart, a fast-acting insulin analog, provides a smoother and more stable profile with lower post-prandial plasma glucose levels that the combination of NPH insulin with regular human insulin before each meal. In several trials, the risk of hypoglycemia, particularly of nocturnal hypoglycemia, was significantly lower with insulin detemir than with NPH insulin. In conclusion insulin detemir offers a better reproducibility as compared with other basal insulins, reduces the risk of hypoglycemia, and may lead the patients to titrate their insulin doses more easily and therefore to achieve more often glycemic objectives. The combination of rapid- and long-acting insulin analogs reproduces a more physiological insulin secretion and thereby reduces the risk of hypoglycemia and improves the overall 24-h glycemic profile.