Current insight in the localized insulin-derived amyloidosis (LIDA): clinico-pathological characteristics and differential diagnosis

Comprehensive investigation of insulin-induced amyloidosis lesions in patients with diabetes at clinical and histological levels: A systematic review

INTRODUCTION

Insulin-derived amyloidosis (AIns), a skin complication in patients with diabetes, causes impaired insulin absorption. This systematic review aims to get a better understanding of this overlooked condition.

METHODS

Comprehensive literature searches were performed in Scopus, PubMed, EMBASE, and Web of Science databases until June 17, 2023. From 19,343 publications, duplicate and irrelevant records were eliminated by title, and the full texts of the remaining studies were examined for validity. Clinical, pathological, and therapeutic findings were extracted from 44 papers.

RESULTS

Forty-four articles were studied that covered 127 insulin-treated patients with diabetes. From the 62 patients with reported age and sex, males had a mean age of 58 years, and females 68.5 years. While AIns were twice as likely to develop in men (66.13 %) as in women (33.87 %), the administered insulin dose was significantly higher in males (p = 0.017). The most common insulin injection site was the abdominal wall (77.63 %). Histological findings showed the presence of amorphous material with the occasional presence of lymphocytes, plasma cells, macrophages, adipocytes, histocytes, and giant cells. The mean HbA1c level was 8.8 % and the need for receiving insulin was increased in AIns. Changing the site of insulin injections and/or surgically removing the nodules were the most common treatments to obtain better insulin uptake and controlled serum glucose levels.

CONCLUSION

This study highlights the importance of AIns, proper rotation of insulin injection site, and post-treatment patient follow-up to recognize and prevent the development of amyloid nodules.

Effectiveness of management protocol for insulin balls in diabetics: a scoping review

Aim

In order to achieve good glycemic control, the prevention and management of insulin balls is important for diabetic patients during insulin therapy. However, insulin balls still occur within the clinical setting. This review evaluated the effectiveness of programs designed to manage insulin balls.

Methods

A scoping review was conducted based on the Japanese and English literature available from a systematic literature search conducted from January 1964 to March 2022. Three databases were searched: PubMed, CINAHL, and Ichushi-Web.

Results

A total of 33 articles met the inclusion criteria, which consisted of 3 for prevention management of insulin balls and 30 for management after the occurrence of insulin balls. Findings for prevention management suggested that the insulin injection technique education (avoidance of repeated injections to the same site) and providing knowledge (about insulin balls) prevented the appearance of insulin balls. As for post-occurrence management, insulin injection technique education (avoidance of injections to the insulin ball, avoidance of repeated injections to the same site, and switching the injection site) improved blood glucose control. Hypoglycemia was observed in all studies that included an assessment of hypoglycemia. None of the studies evaluated long-term effects of either preventive or post-occurrence management.

Conclusions

Providing insulin injection technique education is an effective management protocol for insulin balls. Moreover, education about hypoglycemia is important for patients with insulin balls. Further studies to investigate the long-term effects in the management of insulin balls are needed.

Optimising Insulin Injection Techniques to Improve Diabetes Outcomes

The effectiveness of therapy in patients with diabetes depends on the correct use of the insulin injection technique. However, despite many established recommendations and evidence that an effective insulin injection technique is essential to improve glycaemic control and minimise the risk associated with diabetes, there is still a need to identify impediments to the insulin injection technique among patients and create awareness among patients and healthcare professionals about the importance of the optimisation of insulin injection techniques. This review focuses on the recent advancements in delivery devices, insulin injection technique teaching methods, monitoring, and complication management and highlights regional best practices and recommendations for optimising injection techniques to improve diabetes outcomes.

Localized Insulin-Derived Amyloidosis in Diabetes Mellitus Type 1 Patient: A Case Report

Localized insulin-derived amyloidosis (LIDA) is a rare local complication of subcutaneous insulin application occurring in patients with diabetes type 1 and 2. A 45-year-old woman with an 11-year history of insulin-dependent diabetes mellitus type 1 underwent a mini-abdominoplasty and excision of a long-standing palpable mass in left hypogastric subcutaneous tissue in the area of long-term insulin application. Histopathological examination revealed insulin amyloidosis as a substrate of the mass lesion. Several months after surgery, there was a transient improvement in previously poor diabetes compensation. In addition to local allergic reactions, abscess formation, scarring, lipoatrophy/dystrophy, and lipohypertrophy, LIDA broadens the differential diagnostic spectrum of local insulin injection complications. LIDA has been described as a cause of poor glycemia compensation, probably due to the conversion of soluble insulin into insoluble amyloid fibrils, which prevents insulin from circulating in the blood and regulating glucose blood concentration. Improvement in diabetes compensation has been described in several reports, including our case. LIDA is a rare local complication of subcutaneous insulin application; accurate diagnosis and treatment have clinical consequences. Immunohistochemical or immunofluorescence distinction from other amyloid types is highly recommended.

Lipohypertrophy and Insulin. An Old Dog that Needs New Tricks

OBJECTIVE

To review the current status of practical knowledge related to insulin-associated lipohypertrophy (LH) - an accumulation of fatty subcutaneous nodules commonly caused by repeated injections and/or infusions of insulin into the same site.

METHODS

Review of published literature with additional contributions from leading multidisciplinary experts with the emphasis on clinical aspects including pathophysiology, clinical and economic consequences, diagnosis, prevention and treatment.

RESULTS

LH is the most common dermatologic complication of insulin therapy. Risk factors for the development of lipohypertrophy include repeated delivery of large amounts of insulin into the same location over time, repeated injection trauma to the skin and subcutaneous tissue, and multiple injections using the same needle. Subcutaneous insulin injection in skin areas with lipohypertrophy is associated with reduced pain; however, this problem can interfere with insulin absorption, thereby increasing the likelihood of glucose variability, hypo- and hyperglycemia when a site is changed. Modern visualization technology of the subcutaneous space with ultrasound can demonstrate lipohypertrophy early in the course of its development.

CONCLUSIONS

The physiological and psychological consequences of developing insulin lipohypertrophy can be prevented and treated with education focusing on insulin injection techniques.

Metal-Organic Frameworks as Sensors for Human Amyloid Diseases

Metal-organic frameworks (MOFs) are versatile compounds with emergent applications in the fabrication of biosensors for amyloid diseases. They hold great potential in biospecimen protection and unprecedented probing capabilities for optical and redox receptors. In this Review, we summarize the main methodologies employed in the fabrication of MOF-based sensors for amyloid diseases and collect all available data in the literature related to their performance (detection range, limit of detection, recovery, time of analysis, among other parameters). Nowadays, MOF sensors have evolved to a point where they can, in some cases, outperform technologies employed in the detection of several amyloid biomarkers (amyloid β peptide, α-synuclein, insulin, procalcitonin, and prolactin) present in biological fluids, such as cerebrospinal fluid and blood. A special emphasis has been given by researchers on Alzheimer's disease monitoring to the detriment of other amyloidosis that are underexploited despite their societal relevance (e.g., Parkinson's disease). There are still important obstacles to overcome in order to selectively detect the various peptide isoforms and soluble amyloid species associated with Alzheimer's disease. Furthermore, MOF contrast agents for imaging peptide soluble oligomers in living humans are also scarce (if not nonexistent), and action in this direction is unquestionably required to clarify the contentious link between the amyloidogenic species and the disease, guiding research toward the most promising therapeutic strategies.

The Strategies of Development of New Non-Toxic Inhibitors of Amyloid Formation

In recent years, due to the aging of the population and the development of diagnostic medicine, the number of identified diseases associated with the accumulation of amyloid proteins has increased. Some of these proteins are known to cause a number of degenerative diseases in humans, such as amyloid-beta (Aβ) in Alzheimer's disease (AD), α-synuclein in Parkinson's disease (PD), and insulin and its analogues in insulin-derived amyloidosis. In this regard, it is important to develop strategies for the search and development of effective inhibitors of amyloid formation. Many studies have been carried out aimed at elucidating the mechanisms of amyloid aggregation of proteins and peptides. This review focuses on three amyloidogenic peptides and proteins-Aβ, α-synuclein, and insulin-for which we will consider amyloid fibril formation mechanisms and analyze existing and prospective strategies for the development of effective and non-toxic inhibitors of amyloid formation. The development of non-toxic inhibitors of amyloid will allow them to be used more effectively for the treatment of diseases associated with amyloid.

Peptide Inhibitors of Insulin Fibrillation: Current and Future Challenges

Amyloidoses include a large variety of local and systemic diseases that share the common feature of protein unfolding or refolding into amyloid fibrils. The most studied amyloids are those directly involved in neurodegenerative diseases, while others, such as those formed by insulin, are surprisingly far less studied. Insulin is a very important polypeptide that plays a variety of biological roles and, first and foremost, is at the basis of the therapy of diabetic patients. It is well-known that it can form fibrils at the site of injection, leading to inflammation and immune response, in addition to other side effects. In this concise review, we analyze the current knowledge on insulin fibrillation, with a focus on the development of peptide-based inhibitors, which are promising candidates for their biocompatibility but still pose challenges to their effective use in therapy.

Addendum 1: Forum for Injection Technique and Therapy Expert Recommendations, India

With the emerging complexities in chronic diseases and people's lifestyles, healthcare professionals (HCPs) need to update their methods to manage and educate patients with chronic lifestyle disorders, particularly diabetes. The insulin injection technique (IIT), along with various parameters, must also be updated with newer methods. Forum for Injection Technique and Therapy Expert Recommendations (FITTER), India, has updated its recommendations to cover newer ways of detecting hypoglycaemia and lipohypertrophy, preventing needlestick injuries (NSIs), discouraging the reuse of insulin needles and encouraging good disposal. FITTER, India, is also introducing recommendations to calculate insulin bolus dose. These updated recommendations will help HCPs better manage patients with diabetes and achieve improved outcomes.

[Insulin-derived amyloidosis (insulin ball) and skin-related complications of insulin therapy]

Skin-related complications of insulin therapy have long been a problem as a factor interfering with insulin therapy. Among the traditional skin-related complications, lipoatrophy and insulin allergy have decreased markedly with the development of insulin preparations, but lipohypertrophy is still common in insulin-treated patients. Recently, there have been more reports of a skin-related complication called insulin-derived amyloidosis or insulin ball. Insulin-derived amyloidosis is a condition in which injected insulin becomes amyloid protein and is deposited at the injection site. Insulin-derived amyloidosis causes poor glycemic control and increased insulin dose requirements, which are caused by decreased insulin absorption. Lipohypertrophy also decreases insulin absorption, but insulin-derived amyloidosis causes a more significant decrease in insulin absorption and has a greater clinical impact. Therefore, it is important to make a differential diagnosis between insulin-derived amyloidosis and lipohypertrophy, but sometimes it is difficult to distinguish the two and imaging studies are required. The diagnosis of insulin-derived amyloidosis is often difficult in the general practice, and its pathogenesis and prevalence have not been fully clarified. Recently, it has been reported that insulin-derived amyloidosis can be toxic, suggesting an association with minocycline use. The treatment of insulin-derived amyloidosis and lipohypertrophy is to avoid the site of amyloidosis or lipohypertrophy and inject insulin, but the dose of insulin injection should be reduced. Prevention of both insulin-derived amyloidosis and lipohypertrophy is important, and for this purpose, observations of the insulin injection site and instruction on appropriate insulin injection techniques are necessary, and multidisciplinary cooperation is extremely important.

Two Cases of Insulin-Derived Amyloidosis With Acanthosis Nigricans-Like Changes

ABSTRACT

Insulin-derived amyloidosis (AIns) is a rare iatrogenic subtype of cutaneous amyloidosis occurring at frequent insulin injection sites. Here, we describe 2 cases of AIns accompanied by acanthosis nigricans (AN)-like changes, a rare finding which has been reported fewer than 5 times in the literature. We also report the first case of an AIns nodule being misdiagnosed as a keloid. Both of our patients presented with asymptomatic, hyperkeratotic, pigmented plaques at frequent insulin injection sites, and histopathologic examination showed (1) nodular aggregates of amyloid demonstrating apple-green birefringence with Congo red staining and (2) AN-like features, such as epidermal papillomatosis, hyperkeratosis, and hyperpigmentation. Accurate diagnosis of AIns is crucial, because repeated insulin injection into a nodule can impair glycemic control. However, misdiagnosis is common, as observed with our second patient, whose AIns nodule was misdiagnosed by an outside provider as a keloid, perhaps because of the presence of AN-like features. Our case report adds to the limited but growing body of literature on AIns and significantly increases the number of reported cases of AIns with AN-like features, an even rarer phenomenon.

Artificial Intelligence-Assisted Bioinformatics, Microneedle, and Diabetic Wound Healing: A "New Deal" of an Old Drug

Diabetic wounds severely influence life, facing grand challenges in clinical treatments. The demand for better treatment is growing dramatically. Diabetic wound healing is challenging because of inflammation, angiogenesis disruptions, and tissue remodeling. Based on sequencing results of diabetic patients' skins and artificial intelligence (AI)-assisted bioinformatics, we excavate a potential therapeutic agent Trichostatin A (TSA) and a potential target histone deacetylase 4 (HDAC4) for diabetic wound healing. The molecular docking simulation reveals the favorable interaction between TSA and HDAC4. Taking advantage of the microneedle (MN) minimally invasive way to pierce the skin barrier for drug administration, we develop a swelling modified MN-mediated patch loaded with TSA to reduce the probability of injection-caused iatrogenic secondary damage. The MN-mediated TSA patch has been demonstrated to reduce inflammation, promote tissue regeneration, and inhibit HDAC4, which provides superior results in diabetic wound healing. We envisage that our explored specific drug TSA and the related MN-mediated drug delivery system can provide an innovative approach for diabetic wound treatment with simple, effective, and safe features and find a broad spectrum of applications in related biomedical fields.

Repeated insulin injection without site rotation affects skin thickness - ultrasonographic and histological evaluation

AIMS/INTRODUCTION

The influence of repeated insulin injection on subcutaneous tissue is known, but its impact on the skin is unclear. Therefore, this study aimed to elucidate the impact of repeated insulin injections on the skin.

MATERIAL AND METHODS

The properties of the skin and the subcutaneous tissue were evaluated in 52 insulin-treated adult patients with diabetes with abnormal findings at the site of self-injection (36 with subcutaneous nodules, 16 with suspected subcutaneous tissue induration) by ultrasonography. In all subjects, both normal and abnormal areas were examined. In addition, skin biopsies were performed in four subjects.

RESULTS

The skin thickness of the normal and abnormal skin sites was 1.95 (1.60, 2.50) and 2.80 (2.27, 3.30) mm, respectively (median (first quartile, third quartile)), (P < 0.001). The biopsy specimens revealed slightly thickened and tight bundles of collagen in the dermis. Three patients had amyloid deposits in the subcutaneous tissue, and one also showed these in the dermis. These were positively stained for insulin antibody.

CONCLUSIONS

Repeated insulin injection procedures result in skin thickening. Increased collagen fibers and possibly amyloid deposition in the dermis may be involved. The results reaffirmed the importance of appropriate site rotation in insulin injection and revealed the usefulness of ultrasonographic skin examination in evaluating the self-injection procedure.

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.

Comparative study of the hydrophobic interaction effect of pH and ionic strength on aggregation/emulsification of Congo red and amyloid fibrillation of insulin

Amyloid fibrillation is provoked by the conformational rearrangement of its source. In our previous study, we claimed that the conformational rearrangement of hen egg white lysozyme requires intermolecular aggregation/packing induced. Our proposed causality of the aggregation and amyloid formation was demonstrated by the quantitative dependence of amyloid fibrillation on pH difference from its isoelectric point (pI) and on the square root of ionic strength in order to reduce the intermolecular repulsion due to the shielding effect of electrolytes (DLVO effect). When Congo red has dianionic form at the pH higher than its pKa, it forms ribbon-like micelle colloids under lower ionic strength, while it loses electrostatic repulsion and aggregates to be emulsified in the octanolic phase under the higher ionic strength. These behaviors of Congo red were resembling to molecular assembly of surfactants. In contrast, the amyloid formation of insulin was proportional to the square root of ionic strength at the pH lower than its isoelectric point. Therefore, the trigger for conformational rearrangement of amyloid fibrillation is predominantly gripped by hydrophobic hydration and an electrostatic shielding effect. We concluded that the both behaviors of Congo red and insulin were derived from a driving force related to the hydrophobic hydration.

Determination of amyloid core regions of insulin analogues fibrils

A rapid-acting insulin lispro and long-acting insulin glargine are commonly used for the treatment of diabetes. Clinical cases have described the formation of injectable amyloidosis with these insulin analogues, but their amyloid core regions of fibrils were unknown. To reveal these regions, we have analysed the hydrolyzates of insulin fibrils and its analogues using high-performance liquid chromatography and mass spectrometry methods and found that insulin and its analogues have almost identical amyloid core regions that intersect with the predicted amyloidogenic regions. The obtained results can be used to create new insulin analogues with a low ability to form fibrils.

Abbreviations

a.a., amino acid residues; HPLC-MS, high-performance liquid chromatography/mass spectrometry; m/z, mass-to-charge ratio; TEM, transmission electron microscopy.

Luminescent imaging of insulin amyloid aggregation using a sensitive ruthenium-based probe in the red region

A sensitive and selective strategy to identify insulin fibrils remains a challenge for researchers in amyloid protein research. Thus, it is critical to detect, in vitro, the species generated during amyloid aggregation, particularly the fibrillar species. Here we demonstrate that the luminescent complex cis-[Ru(phen)₂(3,4Apy)₂]²⁺ (RuApy; phen = 1,10-phenanthroline; 3,4Apy = 3,4-diaminopyridine) is a rapid, low-cost alternative to in vitro detection of fibrillar insulin, using conventional optical techniques. The RuApy complex displays emission intensity enhancement at 655 nm when associated with insulin, which enables imaging of the conformational changes of the protein's self-aggregation. The complex shows high sensitivity to fibrillar insulin with a limit of detection of 0.85 μM and binding affinity of 12.40 ± 1.84 μM which is comparable to those of Thioflavin T and Congo red, with the advantage of minimizing background fluorescence, absorption of light by biomolecules, and light scattering from physiologic salts in the medium.

Insulin Fibril Formation Caused by Mechanical Shock and Cavitation

Cavitation can occur when liquids are exposed to pressure waves of sufficient amplitude, producing rapidly expanding and collapsing gas bubbles that generate localized regions of high energy dissipation. When vials containing insulin were subjected to mechanical shock or when ultrasound was applied to the vials, the resulting cavitation events induced formation of insulin amyloid fibril nuclei that were detected by transmission electron microscopy and quantified by fluorescence spectroscopy following staining with the amyloid-sensitive dye thioflavin-T. Dropping insulin solutions in glass vials produced only minute amounts of insulin fibril nuclei, which could be detected by allowing the nuclei to grow. Cavitation-induced formation of amyloid aggregates may be relevant for iatrogenic insulin deposition disease, where insulin fibrils formed in vitro prior to administration to patients could serve as nuclei for growing fibril deposits in vivo.

Degradation of insulin amyloid by antibiotic minocycline and formation of toxic intermediates

Insulin balls, localized insulin amyloids formed at subcutaneous insulin-injection sites in patients with diabetes, cause poor glycemic control owing to impairments in insulin absorption. Our previous study has shown that some insulin balls are cytotoxic, but others are not, implying amyloid polymorphism. Interestingly, the patient with toxic insulin balls had been treated with antibiotic minocycline, suggesting a possible relationship between toxicity of insulin balls and minocycline. However, the direct effect of minocycline on the structure and cytotoxicity of the insulin amyloid is still unclear. Herein, we demonstrated that that minocycline at physiological concentrations induced degradation of insulin amyloids formed from human insulin and insulin drug preparations used for diabetes patients. Interestingly, the process involved the initial appearance of the toxic species, which subsequently changed into less-toxic species. It is also shown that the structure of the toxic species was similar to that of sonicated fragments of human insulin amyloids. Our study shed new light on the clarification of the revelation of insulin balls and the development of the insulin analogs for diabetes therapy.

Alternatives to Insulin for the Regulation of Blood Sugar Levels in Type 2 Diabetes

This short overview focuses on the causation and treatment of type 2 diabetes (T2D). Emphasis is given to the historical basis of understanding this disease and the background leading to emergence of the central role of insulin. The strengths of insulin administration in the treatment of diabetes are profound, but these need to be balanced against several serious shortcomings of its extended use. Some alternative approaches to T2D management are considered. Insulin is no longer considered as the first choice for type 2 diabetes, and an expanding range of new therapeutic possibilities is emerging. While these may lack the potency of insulin, at a minimum, they allow a major reduction in the intensity of insulin use. In view of the rising worldwide incidence of this disease, it is imperative to develop safe and inexpensive means of limiting its potential for impairment of normal functioning.

Insulin-Induced Skin Lipohypertrophy in Type 2 Diabetes: a Multicenter Regional Survey in Southern Italy

INTRODUCTION

Lipohypertrophies (LHs) due to incorrect insulin injection techniques have been described in the literature for decades. Their rate averages 38%, but this is still controversial because of the vast range reported by different publications, most of which fail to describe the selected detection protocol and therefore are not entirely reliable. We still need to identify the real LH rate, and only consistently using a standardized method in a large cohort of insulin-treated (IT) patients make this possible.

METHODS

Our group performed thorough clinical skin examinations on patients suffering from type 2 diabetes mellitus (T2DM): 1247 IT T2DM outpatients were examined according to a standardized protocol, previously published elsewhere, as well as an ultrasound scan of the same skin areas to assess the degree of concordance between the two methods and to evaluate the demographic, clinical, and behavioral risk factors (RF) as well as metabolic consequences of identified LHs.

RESULTS

The concordance between the two methods was 99%. Identified risk factors for LHs were needle reuse, failure to rotate injection sites, and ice-cold insulin injections. High HbA1c values, wide glycemic variability, and longstanding proneness to hypoglycemia with a high rate of ongoing hypoglycemic events proved to be significantly associated with LHs, too; the same applied to cardiovascular and renal complications as well as to living alone and being retired.

CONCLUSIONS

Based on a strict well-structured methodology, our data confirmed what has already been reported in the literature on factors leading to, or associated with, LHs and, for the first time in adults, indicated cryotrauma from ice-cold insulin injections and specific social conditions as factors facilitating LH occurrence. HCPs should therefore plan a yearly clinical examination of all injection sites to improve patient quality of life through better glucose control and a reduced rate of hypoglycemic events.

TRIAL REGISTRATION

Trial registration no. 127-11.01.2019, approved by the Scientific and Ethics Committee of Campania University "Luigi Vanvitelli," Naples, Italy.

Hydroxytyrosol Inhibits Protein Oligomerization and Amyloid Aggregation in Human Insulin

Hydroxytyrosol (HT), one of the main phenolic components of olive oil, has attracted considerable interest for its biological properties, including a remarkable antioxidant and anti-inflammatory power and, recently, for its ability to interfere with the amyloid aggregation underlying several human diseases. We report here a broad biophysical approach and cell biology techniques that allowed us to characterize the molecular mechanisms by which HT affects insulin amyloid aggregation and the related cytotoxicity. Our data show that HT is able to fully inhibit insulin amyloid aggregation and this property seems to be ascribed to the stabilization of the insulin monomeric state. Moreover, HT completely reverses the toxic effect produced by amyloid insulin aggregates in neuroblastoma cell lines by fully inhibiting the production of toxic amyloid species. These findings suggest that the beneficial effects of olive oil polyphenols, including HT, may arise from multifunctional activities and suggest possible a application of this natural compound in the prevention or treatment of amyloid-associated diseases.

Prevalence, Risk Factors, and Clinical Characteristics of Lipodystrophy in Insulin-Treated Patients with Diabetes: An Old Problem in a New Era of Modern Insulin

BACKGROUND

Lipodystrophy has been reported as a common complication in insulin-treated patients, which could lead to unexplained hypoglycemia and suboptimal glycemic control. This study aimed to determine the prevalence, associated risk factors, and clinical characteristics of insulin-induced lipodystrophy in Thai patients.

PATIENTS AND METHODS

This was a cross-sectional study involving insulin-treated patients at Theptarin Hospital, one of the largest diabetes centers in Thailand.

RESULTS

A total of 400 patients were studied (female 53.5%, T2DM 86%, mean age 65.6±15.4 years, duration of diabetes 23.0±10.2 years, median insulin treatment 10 years, usage of insulin analog 72.1%, A1C 7.9±1.6%) . The prevalence of lipohypertrophy (LH) in overall patients was 37.3% (T1DM 46.4% and T2DM 35.8%). The highest prevalence (57.5%) was observed in long-standing (≥10 years) T1DM patients. Multivariate analysis revealed that the duration of insulin use (≥10 years), use of human insulin, and incorrect rotation of injection sites were associated with LH. Patients with LH were found to have 7-times greater risk of unexplained hypoglycemia when compared with patients without LH. Lipoatrophy (LA) was found in only four cases (1.0%). All LA cases had a concurrence palpable area of LH.

CONCLUSION

Insulin-induced lipodystrophy is still an overlooked complication in the conundrum of diabetes care. The presence of lipodystrophy was significantly associated with the occurrence of unexplained hypoglycemia. It should be emphasized to recognize this condition by inspecting and palpating insulin injecting sites regularly, and educate patients to avoid the development of lipodystrophy.

An abdominal wall mass of exogenous insulin amyloidosis in setting of metastatic sarcoma

Exogenous insulin amyloidosis (AIns) is an iatrogenic form of amyloidosis which is found in diabetic patients, generally localized to the site of subcutaneous insulin administration. It may form a discrete mass that could come to clinical attention, and can contribute to abnormal pharmacokinetics of the exogenous insulin, resulting in worsened control of diabetes. In this case report, we describe such a lesion in a 72-year-old man with a history of type 2 diabetes and primary adrenal gland epithelioid sarcoma and discuss the diagnostic challenges it poses.

Investigation of factors that cause insulin precipitation and/or amyloid formation in insulin formulations

Background

Multiple daily subcutaneous injections (MDSIs) are mainly used for formulating an insulin therapy for diabetic patients; however, they also cause insulin-derived amyloidosis (IDA) and lead to poor glycemic control. In addition, for the continuous subcutaneous insulin infusion system (CSII), precipitation frequently causes catheter occlusion and, if the precipitate in the formulations is amyloid, the injection of the insoluble amyloid into the subcutaneous tissue leads to IDA. The aim of this study was to conduct in vitro experiments and present a situation where insulin formulations cause precipitation and amyloid formation.

Methods

Humulin®R and NovoRapid® were used as model formulations for MDSIs and CSII, respectively. The generation of the precipitation was evaluated by measuring turbidity, and amyloid formation was evaluated by using Thioflavin T. Humulin®R was mixed with saline buffer solutions and glucose solutions to evaluate the effect of dilution. In addition, we created an experimental system to consider the effect of the time course of condition changes, and investigated the effects of insulin concentration, m-cresol existence, and pH change on the generation of the precipitate and amyloid in the formulation.

Results

In both the original and diluted formulations, physical stimulation resulted in the formation of a precipitate, which in most cases was an amyloid. The amyloid was likely to be formed at a near neutral pH. On the contrary, although a precipitate formed when the pH was decreased to near the isoelectric point, this precipitate was not an amyloid. Further decreases in pH resulted in the formation of amyloids, suggesting that both the positive and negative charged states of insulin tended to form amyloids. The formulation additive m-cresol suppressed amyloid formation. When additives were removed from the formulation, the amyloid-containing gel was formed in the field of substance exchange.

Conclusions

To consider changes in conditions that may occur for insulin formulations, the relationship between the formation of precipitates and amyloids was demonstrated in vitro by using insulin formulations. From the in vitro study, m-cresol was shown to have an inhibitory effect on amyloid formation.

Extreme Adhesion Activity of Amyloid Fibrils Induces Subcutaneous Insulin Resistance

Insulin-derived amyloidoma, also called an insulin ball, is a skin-related complication of insulin therapy caused by repeated insulin injections at the same site, where native folded insulin changes into amyloid fibrils and forms a mass with a granulomatous reaction. Insulin-derived amyloidoma is a clinically important condition because of its association with subcutaneous insulin resistance, but the precise effect and mechanism of the insulin absorption impairment have not been clarified. We generated insulin-derived amyloidomas in mouse skin, with the amyloidomas large enough to perform insulin tolerance tests in the mass by repeated injections of highly concentrated insulin amyloid fibrils. We demonstrated that the insulin-derived amyloidomas inhibit insulin absorption. By simultaneous administration of insulin and insulin amyloid fibrils, we showed that this effect is due to the amyloid fibril itself in the absence of a granulomatous reaction. In vitro studies revealed that insulin amyloid fibrils have extremely strong adhesion to native human insulin and various insulin analogs. Furthermore, we showed that native insulin that had adhered to insulin amyloid forms amyloid fibrils at physiological pH. These results suggest that the extreme adhesion of insulin amyloid to native insulin is the main mechanism of impaired insulin absorption and amyloidoma growth.