A Critical Appraisal of the Role of Insulin Analogues in the Management of Diabetes Mellitus

Overview of Peptides and Their Potential Roles in Skin Health and Beauty

Peptides are molecules that consist of at least two amino acids linked by peptide bonds. The difference between peptides and proteins is primarily based on size and structure. Typically, oligopeptides consist of fewer than about 10-20 amino acids, and polypeptides consist of more than 20 amino acids, whereas proteins usually are made up more than 50 amino acids and often contain multiple peptide subunits as stated in the International Union of Pure and Applied Chemistry rules. Beyond the nutritional properties, peptides are also structural components of hormones, enzymes, toxins, and antibiotics and play several fundamental physiological roles in the body. Since the introduction of the first commercial peptide drug, insulin, peptide-based drugs have gained increased interest. So far, more than 80 peptide-based drugs have reached the market for a wide range of conditions, such as diabetes, cardiovascular diseases, and urological disorders. Meanwhile, peptides have also gained significant attention in the cosmetic industry because of their potential in boosting skin health. In this review, peptides were comprehensively summarized in the aspects of sources, function, the use of peptides in cosmetics and skin care, and indications for the delivery of cosmetic peptides.

Dynamic Detection of HbA1c Using a Silicon Nanowire Field Effect Tube Biosensor

As an emerging diabetes diagnostic indicator and a dynamic change index, HbA1c can not only reflect the average blood glucose level over a period of time but can also well predict the incidence of related microvascular complications. It is important to develop a detection method that can dynamically characterize HbA1c. Silicon nanowire (SiNW) devices were mass-produced using top-down sputtering technology, and a microdialyzer was installed in a SiNW field effect tube biosensor detection system. Finally, the detection system was used to detect HbA1c levels quantitatively and dynamically in experimental rabbits. Various measurements showed that mass-produced SiNW devices have ideal dimensions, stable structures, and good performance. A series of microscopy results showed that the SiNW surface can be functionalized for intermolecular interactions. The addition of a dialysis device can effectively overcome Debye shielding, making the blood test similar to the pure standard test. Finally, the dynamic detection of HbA1c within 40 h was realized. SiNW biosensors are capable of the dynamic detection of biomolecules, and dynamic observation of the interaction between blood glucose and HbA1c provides new ideas for the diagnosis and treatment of patients with diabetes. Therefore, the SiNW biosensor can reflect the dynamic changes in HbA1c in a shorter time, which has a certain potential value in the clinical treatment of diabetes.

Advances in FGFs for diabetes care applications

BACKGROUND

Diabetes mellitus (DM) is an endocrine and metabolic disease caused by a variety of pathogenic factors, including genetic factors, environmental factors and behavior. In recent decades, the number of cases and the prevalence of diabetes have steadily increased, and it has become one of the most threatening diseases to human health in the world. Currently, insulin is the most effective and direct way to control hyperglycemia for diabetes treatment at a low cost. However, hypoglycemia is often a common complication of insulin treatment. Moreover, with the extension of treatment time, insulin resistance, considered the typical adverse symptom, can appear. Therefore, it is urgent to develop new targets and more effective and safer drugs for diabetes treatment to avoid adverse reactions and the insulin tolerance of traditional hypoglycemic drugs.

SCOPE OF REVIEW

In recent years, it has been found that some fibroblast growth factors (FGFs), including FGF1, FGF19 and FGF21, can safely and effectively reduce hyperglycemia and have the potential to be developed as new drugs for the treatment of diabetes. FGF23 is also closely related to diabetes and its complications, which provides a new approach for regulating blood glucose and solving the problem of insulin tolerance.

MAJOR CONCLUSIONS

This article reviews the research progress on the physiology and pharmacology of fibroblast growth factor in the treatment of diabetes. We focus on the application of FGFs in diabetes care and prevention.

Management of Hyperglycemia in Older Adults with Type 2 Diabetes

The increasing incidence of type 2 diabetes in the general population as well as enhanced life expectancy has resulted in a rapid rise in the prevalence of diabetes in the older population. Diabetes causes significant morbidity and impairs quality of life. Managing diabetes in older adults is a daunting task due to unique health and psychosocial challenges. Medical management is complicated by polypharmacy, cognitive impairment, urinary incontinence, injurious falls, and persistent pain. Health care providers now have several traditional and contemporary pharmacologic agents to manage diabetes. Avoidance of hypoglycemia is critical; however, evidence-based guidelines are lacking due to the paucity of clinical trials in older adults. For many in this population, maintaining independence is more important than adherence to published guidelines to prevent diabetes complications. The goal of diabetes care in older adults is to enhance the quality of life without subjecting these patients to intrusive and complicated interventions. Recent technological advancements such as continuous glucose monitoring systems can have crucial supplementary benefits in the geriatric population.

Assessment of Insulin-related Knowledge among Healthcare Professionals in a Large Teaching Hospital in the United Kingdom

Despite numerous strategies introduced to promote the safe use of insulin, insulin-related medication errors persist. Our aim was to examine the knowledge and self-reported confidence of a range of healthcare professionals regarding insulin use in a large teaching hospital in the North of England. A 16-item electronic questionnaire was prepared in light of locally reported insulin-related incidents and distributed electronically to all healthcare professionals at the hospital over a 4-week study period. A range of healthcare professionals, including nurses, pharmacists, pharmacy technicians, junior doctors and consultants, completed the questionnaires (n = 109). Pharmacists achieved the greatest percentage of mean correct answers overall (49%), followed by consultant doctors (38%) and pharmacy technicians (37%), junior doctors (34%) and nurses (32%). Healthcare professionals were mainly “slightly confident” in their knowledge and use of insulin. Confidence level positively correlated to performance, but number of years’ experience did not result in higher confidence or performance. This small-scale study allowed for a broad assessment of insulin-related topics that have been identified both nationally and locally as particularly problematic. Identifying knowledge gaps may help tailor strategies to help improve insulin knowledge and patient safety.

Evidence-Based Management of Diabetes in Older Adults

The number of older adults with diabetes is rapidly increasing worldwide. A variety of factors contribute to the age-related increase in the incidence of diabetes. The lack of empiric evidence in the field has limited the management guidelines to mostly expert opinion. Given uncertainty over the rate at which to lower blood glucose levels and the optimal method of doing so, the goals of diabetes control in older people must be individualized. If the patient requires insulin therapy, the newer insulins, with their improved pharmacodynamic consistency and reduced risk of hypoglycemia, should be preferred. Several oral agents are preferable for people with sufficient endogenous insulin because they do not cause hypoglycemia when used as monotherapy. Some of these oral agents have been found to have cardioprotective effects. Older people with diabetes also require management of the other risk factors for cardiovascular disease, with antihypertensive drugs, cholesterol-lowering agents and low-dose aspirin. However, the precise targets for blood pressure control and low-density lipoprotein (LDL) cholesterol levels continue to evolve as more data become available. Diabetes care in older adults should focus on enhancing the individual's quality of life rather than trying to normalize blood glucose levels or reach predetermined blood pressure and LDL cholesterol targets.

Comparative efficacy and safety of insulin analogs in hospitalized adults

PURPOSE

The comparative efficacy, safety, and cost-effectiveness of rapid and long-acting insulin analogs compared with regular or neutral protamine Hagedorn nonanalog insulins or with oral antidiabetic agents in hospitalized adults were evaluated.

METHODS

A literature search was conducted to identify studies that compared the effects of rapid-acting, long-acting, or mixed insulin analogs with short- or intermediate-acting insulin or any other oral antidiabetic medication.

RESULTS

Twenty-three primary studies were included in the review. Rapid-acting analogs and basal-bolus analog regimens were found to reduce the duration of hospital stay by approximately one day compared with regular insulin and basal-bolus nonanalog regimens. One large cohort study found an adjusted 48% relative risk reduction in mortality with rapid-acting analogs versus regular insulin in a heterogeneous hospitalized hyperglycemic population. A randomized controlled trial found a significant reduction in postoperative complications with basal-bolus analogs compared with basal-bolus nonanalog insulin. When compared with regular sliding-scale insulin (SSI), fixed-dose insulin glargine with or without insulin glulisine was found to reduce the blood glucose concentration in patients with type 2 diabetes and reduce postoperative complications in surgical patients with diabetes. The quality of evidence was primarily very low or low for most outcomes.

CONCLUSION

A systematic literature review revealed a very low or low quality of evidence, suggesting that, compared with nonanalog regimens, rapid-acting insulin analogs reduce the duration of hospital stay and mortality rates and that basal- bolus analog regimens may reduce the duration of hospital stay and postoperative complications. There is also a low quality of evidence to suggest that a fixed-dose analog regimen of insulin glargine with or without insulin glulisine is more effective than regular SSI for reducing blood glucose concentrations and postoperative complications.

Basal insulin analogues in the treatment of diabetes mellitus: What progress have we made?

Over the past few decades, continuous progress has been made in the development of insulin therapy. Basal insulins were developed around 60 years ago. However, existing basal insulins were found to have limitations. An ideal basal insulin should have the following properties viz. longer duration of action, a flat time-action profile, low day-to-day glycaemic variability, and the potential for flexible dosing. Basal insulins have advanced over the years, from lectin and neutral protamine Hagedorn to the currently available insulin degludec. Currently, the focus is on developing a basal insulin that can give coverage for the entire day, with lesser variability and flexible administration. Insulin degludec has been a significant leap in that direction. In addition, U300 insulin glargine and pegylated lispro represent further developments in basal insulin pharmacotherapeutics.

Proinsulin C-peptide potentiates the inhibitory action of insulin on glucose synthesis in primary cultured rabbit kidney-cortex tubules: Metabolic studies

Effects of equimolar concentrations of proinsulin C-peptide and insulin on glucose synthesis were studied in primary cultures of rabbit kidney-cortex tubules grown in the presence of alanine, glycerol, and octanoate. The rhodamine-labeled C-peptide entered renal tubular cells and localized in nuclei, both in the presence and absence of insulin; preincubations with the unlabeled compound inhibited internalization. C-peptide did not affect glucose formation when added alone but potentiated the inhibitory action of insulin by about 20% due to a decrease in flux through glucose-6-phosphate isomerase (GPI) and (or) glucose-6-phosphatase (G6Pase). GPI inhibition was caused by: (i) increased intracellular contents of fructose-1,6-bisphosphate and fructose-1-phosphate, inhibitors of the enzyme and (ii) reduced level of the phosphorylated GPI, which exhibits higher enzymatic activity in the presence of casein kinase 2. A decrease in flux through G6Pase, due to diminished import of G6P by G6P-transporter from the cytoplasm into endoplasmic reticulum lumen, is also suggested. The data show for the first time that in the presence of insulin and C-peptide, both GPI and G6P-ase may act as regulatory enzymes of renal gluconeogenic pathway.

Comparison of thrice daily biphasic human insulin (30/70) versus basal detemir & bolus aspart in patients with poorly controlled type 2 diabetes mellitus - a pilot study

Background & objectives:

Conventionally, biphasic human insulin (30/70, BHI) is used twice daily for the management of patients with diabetes. However, this regimen is suboptimal to control post-lunch and/or pre-dinner hyperglycaemia in some patients. This study was undertaken to compare the efficacy and safety of thrice-daily biphasic human insulin (30/70, BHI) versus basal detemir and bolus aspart (BB) in patients with poorly controlled type 2 diabetes mellitus (T2DM).

Methods:

In this open labelled randomized pilot study, 50 patients with uncontrolled T2DM on twice-daily BHI and insulin sensitizers were randomized either to BHI thrice-daily or BB regimen. HbA1c, six point plasma glucose profile, increment in insulin dose, weight gain, hypoglycaemic episodes and cost were compared between the two treatment groups at the end of 12 wk.

Results:

Mean HbA_lc (±SD) decreased from 9.0±0.9 per cent at randomization to 7.9±0.8 per cent in BHI (P<0.001) and from 9.4±1.3 to 8.2±1.0 per cent in BB regimen (P<0.001) after 12 wk of treatment. The mean (±SEM) weight gain in patients in the BHI regimen was 1.5±0.33 kg compared to 1.4±0.34 kg in the BB regimen. Insulin dose increment at 12 wk was significantly more in the BB regimen 0.46±0.32 U/kg/day compared to 0.15±0.21 U/kg/day in the BHI regimen (P<0.001). The incidence of major as well as minor hypoglycaemic episodes was not different in both the regimen. The BB regimen was more expensive than the BHI regimen (P<0.001).

Interpretation & conclusions:

The thrice daily biphasic human insulin regimen is non-inferior to the basal bolus insulin analogue regimen in terms efficacy and safety in patients with poorly controlled T2DM. However, these data require further substantiation in large long term prospective studies.

Special considerations with insulin therapy in older adults with diabetes mellitus

Aging is associated with alterations in insulin secretion and action. However, aging per se does not alter the pharmacokinetics of commercially available insulin and its analogues. Insulin therapy in older adults is complicated by psychosocial and physiological changes of aging. Several new insulin and insulin analogue preparations are now available for clinical use. Used as prandial (e.g. insulin lispro, insulin aspart or insulin glulisine) and basal insulin (e.g. insulin glargine, insulin detemir), these analogues simulate physiological insulin profiles more closely than the older conventional insulins. The availability of multiple insulin products provides new opportunities to achieve control of diabetes mellitus. The choice of initial insulin therapy can be made based on blood glucose profiles. Overall, these profiles can be divided into three general patterns that include: (i) round-the-clock hyperglycaemia; (ii) fasting hyperglycaemia with daytime euglycaemia; and (iii) daytime hyperglycaemia with normal fasting blood glucose levels. The prescription of insulin is a dynamic process, and the insulin regimen should be adjusted based on individual response. The goal of diabetes care in older adults is to enhance quality of life without subjecting individuals to complicated treatment regimens that may interfere with their independence in carrying out daily activities.

Cumulative clinical experience with use of insulin lispro: critical appraisal, role in therapy, and patient considerations

We have now at our disposal the new rapid-acting insulin analogs, of which insulin lispro was the first to become commercially available. While the differences in pharmacokinetic and pharmacodynamic characteristics are indisputable, the clinical benefits attained by these changes have not been as clear. In the present review, we discuss the structure, pharmacology, and landmark studies related to insulin lispro. The clinical characteristics of insulin lispro are compared with those of insulin regular and other insulin analogs in different clinical situations. Also included are the aspects of quality of life and cost-effectiveness that may modify the modern practitioner's decision to adopt one type of insulin over another.

Insulin therapy

Insulin therapy is a vital hormone replacement therapy in type 1 diabetes mellitus. In type 2 diabetes, insulin is indicated if glycaemic goals are not reached by oral anti diabetics, as well as for metabolic detoriation, co-morbidities, surgery, pregnancy or contradictions against oral anti diabetics. Insulin preparations are characterized by the onset of the insulin action, the peak profile and duration of action. Available are short acting, long-acting and premixed preparations of human insulin, and insulin analogues. The gold standard of insulin therapy in type 1 diabetes is functional insulin therapy with a basal-bolus insulin regimen and control and adaption of the therapy by the patient. Various insulin regimens are available for treating patients with type 2 diabetes, including basal insulin supported oral therapy, supplementary mealtime injection of short acting insulin or insulin analogues, conventional insulin therapy or a basal bolus procedure. The various insulin preparations and regimens make it possible to adapt the therapy according to the patient's individual need.

Intradermal microneedle delivery of insulin lispro achieves faster insulin absorption and insulin action than subcutaneous injection

BACKGROUND

This study compared insulin lispro (IL) pharmacokinetics (PK) and pharmacodynamics (PD) delivered via microneedle intradermal (ID) injection with subcutaneous (SC) injection under euglycemic glucose clamp conditions.

METHODS

Ten healthy male volunteers were administered 10 international units (IU) of IL at 3 microneedle lengths (1.25, 1.50, or 1.75 mm) in a randomized, crossover fashion on Days 1-3 followed by a repetitive ID 1.5-mm microneedle dose (Day 4) and an SC dose (Day 5).

RESULTS

Microneedle ID delivery resulted in more rapid absorption of IL, with decreased time to maximum insulin concentration (ID vs. SC: 36.0-46.4 vs. 64.3 min, P < 0.05) and higher fractional availability at early postinjection times. ID produced more rapid effects on glucose uptake with shorter times to maximal and early half-maximal glucose infusion rates (GIRs) (ID vs. SC: time to maximum GIR, 106-112 vs. 130 min, P < 0.05; early half-maximal GIR, 29-35 vs. 42 min), increased early GIR area under the curve (AUC), and faster offset of insulin action (shorter time to late half-maximal GIR: 271-287 vs. 309 min). Relative total insulin bioavailability (AUC to 360 min and AUC to infinite measurement) did not significantly differ between administration routes. ID PK/PD parameters showed some variation as a function of needle length. Delivery of ID IL was generally well tolerated, although transient, localized wheal formation and redness were observed at injection sites.

CONCLUSIONS

Microneedle ID insulin lispro delivery enables more rapid onset and offset of metabolic effect than SC therapy and is safe and well tolerated; further study for insulin therapy is warranted.

The effect of healthcare provider education on diabetes management of hospitalised patients

BACKGROUND

The importance of optimising blood glucose (BG) control in hospitalised patients is widely accepted. To determine whether focused education of physicians and nurses would result in measurable changes in glycaemic control, the effect of a diabetes-focused educational programme on point of care (POC) BG measures was monitored.

METHODS

This programme included 2 h symposium and 2 h interactive session. The POC BG measures were determined at 2-month period prior to implementing the programme and the ensuing 7 months after. Outcome parameters included the mean BG values, the incidence of hyperglycaemia (BG > 180 mg/dl) and hypoglycaemia (BG < 60 mg/dl). The outcome parameters were analysed by comparing the Internal Medicine (target service) to other such as Neurology and Surgical Trauma where no programme was offered.

RESULTS

On Internal Medicine, the mean BG decreased soon after implementing the programme and stayed lower than the baseline values over 7 months. The changes were significant at the third, fourth, seventh and the ninth month of the study. Hyperglycaemia decreased significantly (p < 0.05) on the third, fourth, seventh and eighth month, while hypoglycaemia increased following the education programmes. On Neurology and Surgical Trauma, the mean BG values were significantly higher, and hypoglycaemia was significantly lower during the same time frame.

CONCLUSIONS

Implementing an educational programme for healthcare providers had significant effects on the lowering of mean BG values and the incidence of hyperglycaemia, but increased the risk of hypoglycaemia. The merits of such programmes need to be tested before their widespread implementation.

Glycemic control and surgery-optimizing outcomes for the patient with diabetes

Diabetes mellitus (DM) has reached epidemic proportions globally, and its incidence continues to rise. Considering the increasing number of patients diagnosed with diabetes and the associated complications, such as cardiovascular and renal disease, the complexity of care for this population can be very challenging. In addition, specific postoperative complications, such as delayed wound healing, infections, and cardiac dysrhythmias, are more likely to occur in the presence of perioperative hyperglycemia. Recognition of the presence of diabetes and implementation of a diabetic management protocol will optimize patient outcomes by providing guidelines for avoiding such complications. Although comparative studies of the current published protocols are limited, there is agreement that health care facilities must have a protocol in place that considers the individual's health history, planned surgery, and glycemic control to guide management of diabetes.

Assessment of adherence and healthcare costs of insulin device (FlexPen) versus conventional vial/syringe

INTRODUCTION

Diabetes is difficult to manage and treatment involves significant lifestyle adjustments. Unlike the traditional method of insulin administration via the vial and syringe method, insulin pens might be perceived as less cumbersome and have potential to significantly increase patient adherence.

METHODS

Using "real world" data, we examined the differences in adherence and costs between diabetic patients using an insulin FlexPen (Novo Nordisk Inc, Princeton, NJ, USA) and those using traditional vial and syringe administration. Using a retrospective analysis of health insurance claims data between the years 2003 and 2008, we examined patients in the FlexPen cohort and analog vial cohort. Propensity score matching was used to match these cohorts (n=532 in each) according to baseline characteristics.

RESULTS

Adjusted mean medication possession ratio when switched to FlexPen improved by 22 percentage points versus 13 percentage points when continuing to use vials (P=0.001). Diabetes-related healthcare costs when switched to FlexPen versus continuing on to use vials ($3970 vs. $4838, respectively, P=0.9368) and total healthcare costs ($13,214 vs. $13,212, respectively, P=0.9473) were not statistically different.

CONCLUSION

Without significant addition to the cost, insulin administration with FlexPen is associated with an improved adherence among patients who switched from vial-based insulin administration.

Prandial premixed insulin analogue regimens versus basal insulin analogue regimens in the management of type 2 diabetes: an evidence-based comparison

BACKGROUND

Insulin is an effective treatment for type 2 diabetes (T2D), a progressive condition in which insulin deficiency is one of the core defects. When patients with T2D are unable to achieve glycemic goals with diet and oral antihyperglycemic medications, a common starting insulin regimen consists of basal or premixed insulin added to oral antihyperglycemic medications. When glycemic goals are not achieved with the initial insulin regimen, a basal-bolus regimen is necessary.

OBJECTIVE

This article reviews clinical-trial data on the efficacy and safety profile of prandial premixed insulin analogues (insulin aspart and insulin lispro) compared with basal insulin analogues (insulin glargine, insulin detemir, and insulin lispro protamine suspension), with or without a prandial insulin analogue, in the management of T2D.

METHODS

A systematic search of Ovid, MEDLINE, and EMBASE (1995-2007) was performed to identify published randomized controlled trials comparing prandial premixed insulin analogues with basal insulin analogues, with or without prandial insulin, in patients with T2D. The search terms were premixed insulin analogues, premixed insulin, biphasic insulin aspart, insulin aspart 70/30, insulin aspart 50/50, premixed insulin lispro, insulin lispro 75/25, insulin lispro 50/50, glargine, and detemir. Abstracts presented at the 2005 and 2006 meetings of the American Diabetes Association and the European Association for the Study of Diabetes and bibliographies of the identified studies were also reviewed. Predetermined criteria for study inclusion were treatment duration of at least 12 weeks, T2D diagnosed using valid criteria, use of a basal insulin analogue (with or without rapid-acting insulin) as a study comparator, and use of well-accepted end points (eg, glycosylated hemoglobin [HbA(1c)], hypoglycemia, preprandial and postprandial blood glucose).

RESULTS

Of the identified randomized controlled trials, 3 studies compared premixed insulin analogues containing 70% or 75% basal and 30% or 25% rapid-acting insulin analogue with basal insulin analogues only, and 3 studies evaluated premixed insulin analogues containing 50% basal and 50% rapid-acting insulin analogue with basal insulin analogues only. Use of prandial premixed insulin analogues was associated with better overall and postprandial glycemic control. In the studies that compared twice-daily premixed insulin analogues with a basal insulin analogue, changes in HbA(1c) ranged from -1.00% to -2.79% and from -0.42% to -2.36%, respectively (P < 0.01). In the studies that compared thrice-daily premixed insulin analogues with a basal insulin analogue, changes in HbA(1c) ranged from -0.72% to -1.2% and from -0.3% to -0.75%, respectively (P < 0.01). These results were achieved with some increase in overall hypoglycemia, but not in nocturnal or severe hypoglycemia. Doses of the premixed insulin analogues were adjusted during the titration period to achieve glycemic goals.

CONCLUSIONS

The results of this systematic review suggest that regimens consisting of prandial premixed insulin analogues, which provide both basal and prandial insulin coverage, may be used as an initial insulin regimen in patients with T2D to enable better overall, preprandial, and postprandial glycemic control compared with a basal insulin analogue regimen alone. Premixed insulin analogues are an effective option for initiating and intensifying insulin therapy in patients with T2D.

Insulin analogues: an example of applied medical science

Insulin analogues were developed to try and achieve more physiological insulin replacement from injection in the subcutaneous site. Their pharmacokinetics and pharmacodynamics differ from human insulin when injected subcutaneously because of alterations in the amino acid sequence of the insulin molecule. The rapid-acting insulin analogues, lispro, aspart and glulisine, have a rapid onset of action and shorter duration of action because of changes to the B26-30 portion of insulin inhibiting formation of dimers and hexamers. They appear to improve postprandial glucose, incidence of hypoglycaemia and patient satisfaction and, when used in combination with basal insulin analogues, improve glycosylated haemoglobin in comparison to conventional insulin therapy. Additionally, they have been successfully used in children, pregnant women, in pump therapy and as part of premixed biphasic regimens. The two basal insulin analogues, glargine and detemir, developed by adjusting the isoelectric point and adding a fatty acid residue, respectively, have a protracted duration of action and a relatively smooth profile. Their pharmacokinetic and pharmacodynamic profiles have been assessed using euglycaemic clamp protocols. Both analogues have a longer duration of action, less of a peak of activity and a reduced variability with repeated injection. There is some evidence to suggest that detemir may have a slight hepatoselective effect. Clinical studies have shown a lower relative risk of hypoglycaemia and detemir appears to have a weight-sparing action. Insulin analogues represent a successful example of applied medical science.

New therapeutic approaches in type 2 diabetes

Type 2 diabetes is a progressive chronic disease resulting from a dynamic interaction between defects in insulin secretion and insulin action. New molecules have recently been launched and many others are under clinical investigation. Besides classical sulfonylureas and glinides, new insulin secretagogues are now available, which target the incretin gut hormone glucagon-like peptide-1 (GLP-1). Indeed, oral incretin enhancers acting as antagonists of the enzyme DPP-4 (dipeptidylpeptidase-4), which inactivates natural GLP-1,and injectable incretin mimetics (exenatide) or analogues (liraglutide), which reproduce the actions of GLP-1 while resisting to DPP-4, represent new opportunities to stimulate insulin secretion, without increasing the risk of hypoglycaemia and weight gain. Among insulin sensitizers, metformin remains unequivocally the first drug of choice for the treatment of type 2 diabetes, whereas promising drugs as thiazolidinediones (glitazones) were recently challenged because of various safety issues. When insulin is required, insulin analogues, both short-acting and basal ones, may offer some advantages regarding better control of postprandial hyperglycaemia, reduced risk of hypoglycaemia and/or lower weight gain in patients with type 2 diabetes. Emphasis should be put on early detection and intensive management of type 2 diabetes, individualized glucose lowering treatments and goals, stepwise pharmacological strategy avoiding therapeutic inertia, and multiple cardiovascular risk--targeted approach.

Insulin therapy in renal disease

Diabetes mellitus (DM) is the main cause of end-stage renal disease (ESRD). Conversely, chronic renal failure (CRF) is also associated with diverse alterations in carbohydrate and insulin metabolism. CRF-induced metabolic disorders should be borne in mind when treating diabetic patients, to ensure the introduction of adequate therapy adjustments that are in line with the onset of renal function decline. Moreover, several specific therapies employed in CRF may also influence pharmacological therapy of DM in uraemic patients. Adequate glycaemic control has also been associated with a reduction in the onset and progression of diabetic nephropathy as well as in the morbidity and mortality in uraemic diabetic patients during dialysis. Intensive insulin therapy can notably improve glycemic control and it should be considered part of the management of insulin-treated CRF diabetic patients. Insulin analogues have been recently evaluated in CRF diabetic patients, with encouraging results. In this study, we review the more relevant aspects related to insulin therapy in diabetic patients with different degrees of renal failure and in patients with ESRD, both in conservative therapy and dialysis.

Reaching glycaemic targets while minimizing hypoglycaemia in insulin-treated type 2 diabetes patients

Type 2 diabetes mellitus (T2DM) is a progressive disease characterized by both insulin resistance and beta-cell failure, resulting in a decline in insulin secretion and increased blood glucose levels. By the time T2DM is clinically diagnosed, only 50% of normal beta-cell function remains, leading to altered control of fasting and/or postprandial glucose. The aim of this review is to summarize the options for introduction of basal insulin, in particular insulin glargine, and the advantages and disadvantages of using insulin glargine vs. alternative insulins or vs. oral agents. Overall, the studies included in this review show that insulin glargine is associated with a lower risk of hypoglycaemia vs. both neutral protamine Hagedorn insulin and premixed insulin formulations, alongside clinically important improvements in glycaemic control. Furthermore, insulin glargine is associated with greater improvements in glycaemic control vs. intensification of oral therapy. Thus, insulin glargine should be a preferred option when starting insulin therapy for people with T2DM.

[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.

Common crossroads in diabetes management

The prevalence and impact of type 2 diabetes are reaching epidemic proportions in the United States. Data suggest that effective management can reduce the risk for both microvascular and macrovascular complications of diabetes. In treating patients with diabetes, physicians must be prepared not only to tailor the initial treatment to the individual and his or her disease severity but also to advance treatment as necessary and in step with disease progression.

The majority of patients with diabetes are not at goal for glycated hemoglobin A1C, fasting plasma glucose, or postprandial plasma glucose levels. Although lifestyle changes based on improved diet and exercise practices are basic elements of therapy at every stage, pharmacologic therapy is usually necessary to achieve and maintain glycemic control. Oral antidiabetic agents may be effective early in the disease but, eventually, they are unable to compensate as the disease progresses. For patients unable to achieve glycemic control on 2 oral agents, current guidelines strongly urge clinicians to consider the initiation of insulin as opposed to adding a third oral agent. Recent research suggests that earlier initiation of insulin is more physiologic and may be more effective in preventing complications of diabetes. Newer, longer-lasting insulin analogs and the use of simplified treatment plans may overcome psychological resistance to insulin on the part of physicians and patients.

This article summarizes the risks associated with uncontrolled fasting and postprandial hyperglycemia, briefly reviews the various treatment options currently available for type 2 diabetes, presents case vignettes to illustrate crossroads encountered when advancing treatment, and offers guidance to the osteopathic physician on the selection of appropriate treatments for the management of type 2 diabetes.

Insulin structure and function

Throughout much of the last century insulin served a central role in the advancement of peptide chemistry, pharmacology, cell signaling and structural biology. These discoveries have provided a steadily improved quantity and quality of life for those afflicted with diabetes. The collective work serves as a foundation for the development of insulin analogs and mimetics capable of providing more tailored therapy. Advancements in patient care have been paced by breakthroughs in core technologies, such as semisynthesis, high performance chromatography, rDNA-biosynthesis and formulation sciences. How the structural and conformational dynamics of this endocrine hormone elicit its biological response remains a vigorous area of study. Numerous insulin analogs have served to coordinate structural biology and biochemical signaling to provide a first level understanding of insulin action. The introduction of broad chemical diversity to the study of insulin has been limited by the inefficiency in total chemical synthesis, and the inherent limitations in rDNA-biosynthesis and semisynthetic approaches. The goals of continued investigation remain the delivery of insulin therapy where glycemic control is more precise and hypoglycemic liability is minimized. Additional objectives for medicinal chemists are the identification of superagonists and insulins more suitable for non-injectable delivery. The historical advancements in the synthesis of insulin analogs by multiple methods is reviewed with the specific structural elements of critical importance being highlighted. The functional refinement of this hormone as directed to improved patient care with insulin analogs of more precise pharmacology is reported.

Allergy reactions to insulin: effects of continuous subcutaneous insulin infusion and insulin analogues

The purification of animal insulin preparations and the use of human recombinant insulin have markedly reduced the incidence but not completely suppressed the occurrence of insulin allergy manifestations. Advances in technologies concerning the mode of delivery of insulin, i.e. continuous subcutaneous insulin infusion (CSII), and the use of insulin analogues, resulting from the alteration in the amino acid sequence of the native insulin molecule, may influence the immunogenicity and antigenicity of native insulin. Instead of increasing allergy reactions, CSII has been reported to represent a successful alternative treatment in diabetic patients presenting local or generalized allergy to insulin or other components (zinc, protamine) of conventional treatment. Most recent reports concern CSII-treated patients using short-acting insulin analogues (essentially insulin lispro), although the precise role of these insulin analogues remains unclear as allergy to them has also been described. Finally, data on antigenicity and immunogenicity of long-acting insulin analogues (glargine, detemir), which may mimic the basal insulin delivery with CSII, remain scarce at present.

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.

Lipodystrophy reactions to insulin: effects of continuous insulin infusion and new insulin analogs

Management of diabetes mellitus can be responsible for cutaneous adverse events. For example, lipoatrophy or lipohypertrophy can develop at the site of insulin injections. Lipohypertrophy remains a frequent complication of insulin therapy irrespective of the insulin source and mode of administration. Lipoatrophy at insulin injection sites is considered to be an immune complex-mediated inflammatory lesion; however, it has become a rare event since the advent of human insulin. Nowadays, continuous subcutaneous insulin infusion (CSII) using a portable pump and/or injections of insulin analogs with an altered amino acid sequence compared with native insulin may cause lipodystrophy in diabetic patients. Some case reports describe the recovery of lipoatrophy following the use of CSII and/or short-acting insulin analogs. Conversely, exceptional cases of lipoatrophy have occurred in patients receiving lispro insulin analog via CSII. Lipodystrophy reactions remain a potential problem when managing diabetic patients with new insulin therapy technologies.

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.

Insulin detemir in the treatment of type 1 and type 2 diabetes

Insulin detemir is a soluble long-acting human insulin analogue at neutral pH with a unique mechanism of action. Following subcutaneous injection, insulin detemir binds to albumin via fatty acid chain, thereby providing slow absorption and a prolonged metabolic effect. Insulin detemir has a less variable pharmacokinetic profile than insulin suspension isophane or insulin ultralente. The use of insulin detemir can reduce the risk of hypoglycemia (especially nocturnal hypoglycemia) in type 1 and type 2 diabetic patients. However, overall glycemic control, as assessed by glycated hemoglobin, is only marginally and not significantly improved compared with usual insulin therapy. The weight gain commonly associated with insulin therapy is rather limited when insulin detemir is used. In our experience, this new insulin analogue is preferably administrated at bedtime but can be proposed twice a day (in the morning and either before the dinner or at bedtime). Detemir is a promising option for basal insulin therapy in type 1 or type 2 diabetic patients.

Management of diabetes-related hypoglycemia

Iatrogenic hypoglycemia is the main factor limiting aggressive and optimal diabetes management. Rather than being an inevitable consequence of optimal glycemic control, however, hypoglycemia is avoidable and generally straightforward to manage when it occurs. Professional caregivers, patients, and their families are often fearful of hypoglycemia, even though most episodes are minor and easily self-treated. Understanding the factors contributing to hypoglycemia risk and how to minimize its occurrence is an essential part of diabetes care. Building on the physiologic fundamentals presented in the accompanying review, the incidence, mortality/morbidity, clinical symptoms, severity classification, and psychosocial impact of hypoglycemia are described here. Appropriate selection and titration of therapeutic agents, including insulin analogs with more predictable time-action profiles than human insulin formulations, can reduce hypoglycemia risk. Patient education about hypoglycemia prevention, including symptom recognition and necessity of rapid treatment, behavioral modification, and the importance of frequent blood glucose monitoring should accompany all therapeutic interventions.

Patient-reported outcomes in a trial of exenatide and insulin glargine for the treatment of type 2 diabetes

Background

Patient-reported measures can be used to examine whether drug differences other than clinical efficacy have an impact on outcomes that may be important to patients. Although exenatide and insulin glargine appear to have similar efficacy for treatment of type 2 diabetes, there are several differences between the two treatments that could influence outcomes from the patient's perspective. The purpose of the current study was to examine whether the two drugs were comparable as assessed by patient-reported outcomes using data from a clinical trial in which these injectable medications were added to pre-existing oral treatment regimens.

Methods

Patients were randomized to either twice daily exenatide or once daily insulin glargine during a 26-week international trial. At baseline and endpoint, five patient-reported outcome measures were administered: the Vitality Scale of the SF-36, The Diabetes Symptom Checklist – Revised (DSC-R), the EuroQol EQ-5D, the Treatment Flexibility Scale (TFS), and the Diabetes Treatment Satisfaction Questionnaire (DTSQ). Change from baseline to endpoint was analyzed within each treatment group. Group differences were examined with General linear models (GLMs), controlling for country and baseline scores.

Results

A total of 549 patients with type 2 diabetes were enrolled in the trial, and current analyses were conducted with data from the 455 per protocol patients (228 exenatide and 227 insulin glargine). The sample was primarily Caucasian (79.6%), with slightly more men (55.2%) than women, and with a mean age of 58.5 years. Paired t-tests found that both treatment groups demonstrated statistically significant baseline to endpoint change on several of the health outcomes instruments including the DSC-R, DTSQ, and the SF-36 Vitality subscale. GLMs found no statistically significant differences between groups in change on the health outcomes instruments.

Conclusion

This analysis found that both exenatide and insulin glargine were associated with significant improvements in patient-reported outcomes when added to oral medications among patients with type 2 diabetes. Despite an additional daily injection and a higher rate of gastrointestinal adverse events, treatment satisfaction in the exenatide group was comparable to that of the glargine group, possibly because of weight reduction observed in patients treated with exenatide.

Case study: lessons learned in the care of a 63-year-old woman with type 2 diabetes

Control of type 2 diabetes mellitus (DM) has deteriorated rather than improved during the last decade in the United States, despite a greater understanding of the disease and the availability of various therapeutic options. Achieving recommended glycemic targets in patients with type 2 DM requires overcoming several barriers, including the fear of hypoglycemia and its associated consequences. Insulin analogues offer new options in diabetes management and may help patients achieve better glycemic control while limiting the incidence of hypoglycemic episodes. Greater awareness of the symptoms of hypoglycemia, intensified blood glucose self-monitoring, and new diabetes treatment options allow for achievement of glycemic targets without increased risk of hypoglycemic episodes. A case study of a 63-year-old woman with type 2 DM offers important lessons learned in diabetes management.

Strategies for testing long-term transcutaneous amperometric glucose sensors

OBJECTIVES

Transcutaneous and embedded devices were developed for use in characterizing the in vivo performance of subcutaneously implanted glucose sensors. The devices were used as a portal for accessing electrochemical glucose sensors from the exterior. They were designed to prevent the sensors from being pulled out of the animals and the sensor leads from breaking. Development of the devices took into consideration rodent mobility, infection control, and animal welfare balanced with sensor durability, accessibility, and functionality.

METHODS

Our approach was developed over five animal protocols spanning a period of 6 months. A total of 68 sensors were implanted with 60 associated devices in 22 Sprague-Dawley outbred rats.

RESULTS

The average sensor lifetime was 11.2 +/- 3.1 days with a maximum of 56 days. All-cause sensor failure averaged one sensor per day. As implantation devices were modified, failure attributable to the device was decreased by 40%. The resulting devices showed good durability and allowed for easy sensor access and testing.

CONCLUSIONS

These data represent baseline sensor function against which future sensor improvements may be measured. The new devices and techniques described should be a valuable tool in the development of continuous glucose sensors.

Diabetes in overweight pediatric patients

Diabetes mellitus (DM) is a growing problem among youth. Although type 1 (insulin-dependent) DM is a disease typically diagnosed during childhood or adolescence, estimates indicate that < or = 45% of new diabetes cases in children are type 2. Children with new-onset type 2 DM are often overweight, aged 10 years or older, have a family history of the disease, and are members of a racial/ethnic minority group. DM treatment has progressed greatly in recent decades. Inadequate therapy, urine testing, glycosylated hemoglobin levels of >10%, and high rates of diabetic complications that were common in the past have yielded to more effective treatments, accurate monitoring, and better outcomes. Insulin pumps and insulin analogues represent promising new avenues that have enhanced convenience, cost-effectiveness, patient satisfaction, and metabolic control of childhood DM.