Insulin-binding Antibodies Research Articles

Increased C-Peptide Immunoreactivity in Insulin Autoimmune Syndrome (Hirata Disease) Due to High Molecular Weight Proinsulin.

BackgroundDetermination of C-peptide is important in the investigation of unexplained hyperinsulinemic hypoglycemia because a high C-peptide concentration usually indicates endogenous insulin hypersecretion. Insulin autoimmune syndrome (IAS) denotes hyperinsulinemic hypoglycemia due to insulin-binding antibodies that prolong insulin half-life. C-peptide clearance is considered to be unaffected, and although a marked C-peptide immunoreactivity in hypoglycemic samples has been reported, it has been suspected to be artifactual. High-resolution mass spectrometry enables examination of the basis of C-peptide-immunoreactivity in IAS.MethodsPrecipitation of plasma with polyethylene glycol was followed by C-peptide immunoassay. Plasma peptides extracted by solvent precipitation were characterized by nano-LC–MS/MS and analyzed using an untargeted data-dependent method. Peptides related to proinsulin, in amino acid sequence, were identified using proprietary bioinformatics software and confirmed by repeat LC–MS/MS analysis. Gel filtration chromatography coupled to LC–MS/MS was used to identify proinsulin-related peptides present in IAS immunocomplexes. Results were compared with those from C-peptide immunoassay.ResultsPolyethylene glycol precipitation of IAS plasma, but not control plasma, depleted C-peptide immunoreactivity consistent with immunoglobulin-bound C-peptide immunoreactivity. LC–MS/MS detected proinsulin and des 31,32 proinsulin at higher abundance in IAS plasma compared with control plasma. Analysis by gel filtration chromatography coupled to LC–MS/MS demonstrated proinsulin and des 31,32 proinsulin, but no C-peptide, in plasma immunocomplexes.ConclusionsAntibody binding can enrich proinsulin and des 31,32 proinsulin in IAS immunocomplexes. Proinsulin cross-reactivity in some C-peptide immunoassays can lead to artifactually increased C-peptide results.

Analysis of the clinical characteristics of insulin autoimmune syndrome induced by exogenous insulin in diabetic patients

BackgroundThe exact incidence, clinical features and uniform diagnostic criteria of exogenous insulin autoimmune syndrome (EIAS) are still unclear. The purpose of this study is to explore the clinical characteristics of EIAS and to provide a structural approach for clinical diagnosis, treatment and prevention.MethodsThe literature on EIAS in Chinese and English from 1970 to 2020 was collected for retrospective analysis.ResultsA total of 122 patients (33 males and 73 females) were included in the study with a median age of 67 years (range 14–86) and a median HbA1c of 7.7%. EIAS mainly occurred in type 2 diabetes mellitus patients using premixed insulin. Symptoms manifested were hypoglycemia in 86.54%, recurrent episodes of symptomatic hypoglycemia in 35.58%, nocturnal hypoglycemia along with daytime hyperglycemia in 21.15% and recurrent hypoglycemia after discontinued insulin in 64.43%. The onset of symptoms occurred at night, in the early morning or during fasting, ranging from a few days to 78 months after the administration of insulin. The mean blood glucose level during the hypoglycemic phase was 2.21 mmol/L (range 1–3.4), and the serum insulin levels were mainly ≥ 100 U/mL and were associated with low C-peptide levels (≤ 10 ng/ml). Insulin autoantibodies (IAAs) were positive in all EIAS patients. The 75-g extended oral glucose tolerance test (OGTT) mainly showed a diabetic curve. Pancreatic imaging was unremarkable. Withdrawal of insulin alone or combination of oral hypoglycemic agents or replacement of insulin formulations or with corticosteroid treatment eliminated hypoglycemia in a few days to 3 months. IAA turned negative in 6 months (median, range 1–12). No hypoglycemia episodes were observed at a median follow-up of 6 months (range 0.5–60).ConclusionsEIAS is an autoimmune disease caused by insulin-binding antibodies in susceptible subjects. Insulin antibodies change glucose dynamics and could increase the incidence of hypoglycemic episodes. Detection of insulin antibodies is the diagnostic test. Changing therapeutic modalities reduced the incidence of hypoglycemic episodes.

Assessment and Management of Anti-Insulin Autoantibodies in Varying Presentations of Insulin Autoimmune Syndrome.

ContextInsulin autoimmune syndrome (IAS), spontaneous hyperinsulinemic hypoglycemia due to insulin-binding autoantibodies, may be difficult to distinguish from tumoral or other forms of hyperinsulinemic hypoglycemia, including surreptitious insulin administration. No standardized treatment regimen exists.ObjectivesTo evaluate an analytic approach to IAS and responses to different treatments.Design and SettingObservational study in the UK Severe Insulin Resistance Service.PatientsSix patients with hyperinsulinemic hypoglycemia and detectable circulating anti–insulin antibody (IA).Main Outcome MeasuresGlycemia, plasma insulin, and C-peptide concentrations by immunoassay or mass spectrometry (MS). Immunoreactive insulin was determined in the context of polyethylene glycol (PEG) precipitation and gel filtration chromatography (GFC). IA quantification using ELISA and RIA, and IA were further characterized using radioligand binding studies.ResultsAll patients were diagnosed with IAS (five IgG, one IgA) based on a high insulin/C-peptide ratio, low insulin recovery after PEG precipitation, and GFC evidence of antibody-bound insulin. Neither ELISA nor RIA result proved diagnostic for every case. MS provided a more robust quantification of insulin in the context of IA. One patient was managed conservatively, four were treated with diazoxide without sustained benefit, and four were treated with immunosuppression with highly variable responses. IA affinity did not appear to influence presentation or prognosis.ConclusionsIAS should be considered in patients with hyperinsulinemic hypoglycemia and a high insulin/C-peptide ratio. Low insulin recovery on PEG precipitation supports the presence of insulin-binding antibodies, with GFC providing definitive confirmation. Immunomodulatory therapy should be customized according to individual needs and clinical response.

Poor glycemic control attributable to insulin antibody in a fulminant type 1 diabetes patient under hemodialysis: successful treatment with double filtration plasmapheresis and prednisolone

BackgroundInsulin antibody appears in approximately 40% of insulin users using human insulin and insulin analog formulations. Insulin antibody, characterized by high affinity and low insulin antibody binding capacity (% bound), rarely causes clinical problems including poor glycemic control. Recently, the insulin antibody against human insulin causing deterioration of glycemic control, characterized by low affinity and high insulin antibody binding capacity similar to those observed in insulin autoimmune syndrome, has been reported.Case presentationA 62-year-old male developing fulminant type 1 diabetes showing rapid hyperglycemia (602 mg/dL) and normal range of glycoalbumin (GA) (18.4%) in the introductory stage of hemodialysis (HD) was transferred to our hospital 3 weeks after the onset of diabetes. He had been administered insulin intensification therapy in other medical clinic; however, his glycemic control remained poor, showing ketoacidosis. After hospitalization, he was initially administered intravenous insulin for 2 days and then switched to subcutaneous intensification therapy (24 U/day); the dose was gradually increased maximum of 72 U/day within 2 months. His glycemic control deteriorated despite high-dose insulin administration and change in the insulin type. Insulin antibody was detected, insulin antibody binding capacity (% bound) was of a high value (89.5%), GA was 32.9%, and casual blood glucose widely changed in continuous glucose monitor, suggesting that unstable blood glucose fluctuations caused by insulin antibody; therefore, treatment with double filtration plasmapheresis (DFPP) and prednisolone (PSL) was performed. The insulin dose reduced, and glycemic control improved from 1 month after the commencement of treatment. Subsequently, insulin antibody level remained high; however, after 6 months, % bound declined (20.9%), and glycemic control improved (GA 23.7%) by PSL (gradually reduced to 5 mg/day). The Scatchard plots also indicated the effectiveness with DFPP and PSL therapy.ConclusionsThe authors present a unique case of fulminant type 1 diabetes developing during the HD introduction period. Although this is a rare complication, physicians specializing in dialysis therapy should also keep in mind that this is a life-threatening complication if the treatment is delayed and that concomitant therapy with apheresis such as DFPP and long-term steroids is effective in some cases when glycemic control deteriorates attributable to insulin antibody.

Diagnosis of insulin autoimmune syndrome using polyethylene glycol precipitation and gel filtration chromatography with ex vivo insulin exchange.

SummaryContextInsulin‐binding antibodies may produce severe dysglycaemia in insulin‐naïve patients (‘insulin autoimmune syndrome’ (IAS) or Hirata disease), while rendering routine insulin assays unreliable.ObjectiveTo assess the performance of clinically used insulin assays and an optimal analytical approach in the context of IAS.DesignObservational biochemical study of selected patients with hyperinsulinaemic hypoglycaemia.PatientsThree patients without diabetes with recurrent spontaneous hyperinsulinaemic hypoglycaemia and ‘positive’ insulin antibodies.MeasurementsA panel of clinically used insulin assays (Siemens ADVIA ® Centaur, Siemens Immulite® 2000, DiaSorin LIAISON ® XL, PE AutoDELFIA ® and the Beckman Coulter Access® 2) were used before and after plasma dilution or polyethylene glycol (PEG) precipitation. Anti‐insulin IgG antibodies were measured by Isletest™‐IAA ELISA. Gel filtration chromatography (GFC) was undertaken with and without preincubation of plasma with exogenous insulin.ResultsDilution of IAS plasma with assay‐specific buffer increased insulin recovery, supporting negative immunoassay interference by antibodies. PEG precipitation of IAS plasma decreased insulin recovery using all assays except the Immulite® 2000. GFC discriminated high molecular weight and monomeric insulin, while ex vivo addition of exogenous insulin to plasma increased insulin bound to antibody, thereby improving the sensitivity of detection of insulin immunocomplexes.ConclusionsImmunoprecipitation with PEG must be used with caution in screening for insulin–antibody complexes as results are assay dependent. GFC with addition of exogenous insulin can identify significant insulin immunocomplexes with enhanced sensitivity, with attendant greater clinical utility and avoidance of radiolabelled reagents.

Association of morning fasting blood glucose variability with insulin antibodies and clinical factors in type 1 diabetes.

The fasting blood glucose concentration in type 1 diabetes may vary without being much affected by diet and exercise. This study aimed to identify association of morning fasting blood glucose concentration variability with insulin antibodies and clinical factors. The subjects in this study were 54 patients with type 1 diabetes who had high variation of fasting blood glucose. The insulin antibody level was measured, and correlations of glycemic variability with antibody levels, binding rates, and other clinical factors were investigated. The standard deviation (SD) of the 30-day morning self-monitored fasting blood glucose concentration (FBG SD) was evaluated as an index of glycemic variability. The mean glucose level was 159.8±42.1 mg/dL and the FBG SD was 47.5±22.0 mg/dL. Glycemic variability (FBG SD) was positively correlated with insulin antibody level, but not with insulin antibody binding rate, and had a negative correlation with C-peptide immunoreactivity/plasma glucose (CPR/PG) and positive correlations with diabetes duration, basal insulin dose and bolus insulin dose. Glycemic variability was not correlated with BMI, HbA1c or age. In multiple regression analysis of glycemic variability, CPR/PG was the only significant related factor. The results showed that glycemic variability was mainly influenced by endogenous insulin secretion capacity and was high in patients with high insulin antibody levels. In some patients with a high insulin antibody titer, the antibody may have an effect on the variability of the fasting glucose concentration in type 1 diabetes.

Insulinoma in a Young Female Patient With Systemic Lupus Erythematosus: A Case Report

Fasting hypoglycemia may occur in subjects with systemic lupus erythematosus (SLE) when accompanied with insulin-binding antibodies or insulin-receptor antibodies. However, insulinoma has not been reported in SLE subjects with hypoglycemia. We present a case report and review the relevant literature. A 26-year-old female with underlying SLE experienced several episodes of neuropsychiatric symptoms in a fasting state. The steroid dosage was titrated up, but in vain. Timely imaging studies showed a pancreatic tumor, and insulinoma was proven by pathology. Hypoglycemia did not recur after surgery. Physicians should distinguish insulinoma from autoimmunity-mediated hypoglycemia in SLE patients with fasting hypoglycemia.

Hypoglycemia due to insulin binding antibodies in a patient with insulin-treated type 2 diabetes and Graves’ disease

To the Editor, Insulin autoimmune syndrome (IAS) showed hypoglycemia, hyperinsulinemia, positive insulin antibodies without insulin injection history. Some patients with diabetes, treated with insulin, also showed these signs. The first case of IAS was reported in 1970s. [1, 2]. IAS can be induced by autoimmune diseases, some drugs, such as methimazole [3]. Here we report one case of special IAS, who suffered from type 2 diabetes concomitant with Graves’ disease. This an 85-year-old woman diagnosed with type 2 diabetes 30 years ago. She accepted oral antidiabetic drugs initially, and switched to insulin injection therapy (Novolin 30R 12 u/day) 5 years ago. About 1 year ago, she began to experiencing recurrent cold sweat, hunger, palpitation, and other symptoms of hypoglycemia, with her peripheral blood glucose ranged from 3.0–4.0 mmol/L during the night and morning. Hypoglycemia episodes still occurred after insulin treatment was suspended. Meanwhile she appeared weight loss, palpitation, chest tightness, fatigue, and lower extremity edema. One month prior to admission, the patient began to appearing eyelid edema, proptosis, photophobia, tearing, redness and pain of eye, polyphagia, heat intolerance, sweating, irritability, and stool frequency. She has hypertension and dyslipidemia history. Physical examination revealed a thinly built woman, BMI 20.7 kg/m, BP 160/70 mmHg, pulse 106/min. Her skin appeared sweeting and hot. She appeared wider palpebral fissures, proptosis, limited eye movements, conjunctival edema, and hyperemia. The movements of the lids were jerky and spasmodic, and the lightly closed lids tremor. Thyroid examination revealed II degrees of goiter with marked tremor and vascular murmur. Thyroid function tests revealed that TSH 0.01 lU/mL, T4 223.18 nmol/l, FT4 34.8 pmol/l, rT3 0.58 ng/ml, thyroglobulin 27.73 ng/ml, Anti-Tg 906.1 IU/ml, TPO [ 600 IU/ml, TRAB 20.8 IU/ml, ESR 64 mm/h. Serum total insulin concentration was 552.3 uU/ml, free insulin concentration 394.4 uU/ml, and Iab binding rate 70.6 %. Scatchard analysis revealed that the serum Iab constituted by two types binding sites which were high-affinity with low capacity (k1 = 3.125 9 10 mol/l, b1 = 37.5 9 10 mol/l) and low-affinity with high capacity (k2 = 1.0 9 10 mol/l, b2 = 5.918 9 10 mol/l), (Fig. 1). Insulin binding antibodies analysis suggested that it was IgG with k light chains. Ultrasound showed bilateral thyroid swelling, diffuse lesions. Abdominal magnetic resonance imaging revealed no abnormalities. The patient was diagnosed with Grave’s diseases, Grave’s ophthalmopathy and IAS, and start receiving prednisone (20 mg/day) and methimazole (10 mg qd) treatment. The insulin injection treatment (Novolin 30R) continued and the dose increased along with blood glucose change. After treatment for 1 month, symptoms including palpitation, heat intolerance, fatigue relieved, photophobia and tearing relieved, meanwhile hypoglycemia attack disappeared. After 2 months of treatment, her serum insulin levels returned to normal range and insulin antibody became X. Wang X. Xu X. Zhao X. Ma H. Yu H. Gong F. Chen (&) No. 3 People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, China 280# MoHe Road, Shanghai 201900, People’s Republic of China e-mail: 903561138@qq.com; fengling_chen@hotmail.com

Interaction of enterovirus infection and cow's milk‐based formula nutrition in type 1 diabetes‐associated autoimmunity

Enteral virus infections and early introduction of cow's milk (CM)-based formula are among the suggested triggers of type 1 diabetes (T1D)-associated autoimmunity, although studies on their role have remained contradictory. Here, we aimed to analyse whether interactions between these factors might clarify the controversies. The study population comprised 107 subjects developing positivity for at least two T1D-associated autoantibodies and 446 control subjects from the Finnish diabetes prediction and prevention cohort. Enterovirus, rotavirus, adenovirus, respiratory syncytial virus and bovine insulin-binding antibodies were analysed from prospective serum samples at 3-24 months of age. Data on infant cow's milk exposure were available for 472 subjects: 251 subjects were exposed to cow's milk before 3 months of age and 221 subjects later in infancy. Signs of an enterovirus infection by 12 months of age were associated with the appearance of autoimmunity among children who were exposed to cow's milk before 3 months of age. Cox regression analysis revealed a combined effect of enterovirus infection and early cow's milk exposure for the development of ICA and any of the biochemically defined autoantibodies (p = 0.001), of IAA (p = 0.002), GADA (p = 0.001) and IA-2A (p = 0.013). The effect of enterovirus infection on the appearance of T1D-associated autoimmunity seems to be modified by exposure to cow's milk in early infancy suggesting an interaction between these factors. Moreover, these results provide an explanation for the controversial findings obtained when analysing the effect of any single one of these factors on the appearance of T1D-associated autoimmunity.

Impact, orthodoxy and peer review

Impact, orthodoxy and peer review

Safety and Efficacy of AIR Inhaled Insulin Compared with Subcutaneous Insulin in Patients Having Diabetes and Asthma: A 12-Month, Randomized, Noninferiority Trial

Long-term safety and efficacy of AIR((R)) inhaled insulin (Eli Lilly and Co., Indianapolis, IN) (AIR is a registered trademark of Alkermes, Inc., Cambridge, MA) in patients with diabetes and concomitant lung disease remain to be established. This 1-year, randomized, open-label, active comparator, two-arm, parallel study compared the safety and efficacy of AIR insulin to subcutaneous (SC) insulin in patients having type 1 or type 2 diabetes and asthma. Patients with type 2 diabetes continued taking their prestudy oral antihyperglycemic medication. Change in hemoglobin A1C from baseline to end point was similar for the AIR insulin and SC insulin groups (-0.063 +/- 0.128% and -0.315 +/- 0.128% respectively, P = 0.105), but noninferiority failed to be achieved (the upper limit of the 95% confidence interval [-0.053, 0.555] was >0.4%). The total daily prandial dose increased more in the AIR insulin group than in the SC insulin group (0.150 U/kg and 0.044 U/kg, respectively, P = 0.002). Safety profiles were generally comparable between treatments. At end point, forced expiratory volume in 1 s (FEV(1))/forced vital capacity (FVC) postbronchodilator (-0.016 +/- 0.005 vs. 0.002 +/- 0.005, P = 0.006) and diffusing capacity of the lung for carbon monoxide (-1.214 +/- 0.325 mL/min/torr vs. -0.383 +/- 0.311 mL/min/torr, P = 0.028) both decreased more in the AIR insulin group than in the SC insulin group, but the differences were not present at follow-up. FEV(1) and FVC were similar between treatment groups at end point. Incidences of hypoglycemia were comparable between groups. Insulin antibody binding increased more in the AIR insulin group. Cough was the most common adverse event; however, there was no difference in incidence between the AIR insulin (15.3%) and SC insulin (12.4%) treatment groups (P = 0.572). In patients who have diabetes and asthma, AIR insulin demonstrated glycemic efficacy similar to SC insulin. Additionally, the safety profile of AIR insulin in patients with and without asthma is consistent.

Is there a relationship between genetically determined haptoglobin phenotype and insulin-dependent diabetes mellitus (IDDM)?

The possible relationship between genetically determined haptoglobin phenotype and insulin-dependent diabetes (IDDM), circulating insulin antibodies and the occurrence of microangiopathy was studied in 144 IDDM. There were no differences regarding the distribution of Hp-phenotypes in 144 patients in comparison with a control population (n = 1726). Irrespective of the Hp-phenotype, the degree and severity of diabetic complications (retinopathy and/or nephropathy) significantly increased with the duration of diabetes. There was no relationship between Hp-phenotype and diabetic microangiopathy (retinopathy, nephropathy). No association existed between Hp-phenotype and the percentage of insulin antibody binding. Regardless of the Hp-phenotype, the insulin antibody concentration decreased with increasing duration of diabetes. Insulin binding parameters (maximum binding capacity and equilibrium dissociation constant) were found to vary considerably with the Hp-phenotypes among IDDM. For a given duration of diabetes the equilibrium dissociation constant increased significantly in the range from Hp 1-1, Hp 2-1 to Hp 2-2 phenotype. There was a direct relationship between the logarithm of the equilibrium dissociation constant and the degree of metabolic control, i.e. the lower the dissociation constant the better the metabolic balance. In conclusion, the results do not provide support for a putative relationship between Hp-phenotype and IDDM. However, differences between insulin binding parameters, in dependence on the Hp-phenotype may be of clinical importance.

The role of insulin antibodies in insulin treatment of type I diabetes.

We investigated equilibrium plasma binding patterns of insulin in 45 juvenile diabetics treated with conventional insulin preparations. Insulin binding parameters were evaluated by Scatchard analysis of the binding data. Stable diabetics had significantly lower equilibrium dissociation constants than labile, thus suggesting an enhanced insulin depot effect due to stronger insulin binding. Correlation of insulin binding data with a glycemic control index yielded a positive relationship between insulin antibody binding and the degree of glycemic control. Insulin neutralization as detected by a relationship between maximum binding capacity of high affinity antibodies and insulin requirement could only be found if patients with poor diabetes control were excluded. Similarly, the well-known promoting influence of residual beta-cell functional capacity (assessed by C-peptide levels) on diabetic stability was observed only after exclusion of patients with higher insulin antibody binding. These data suggest that insulin antibodies are influencing insulin treatment of diabetics in a dual way. They may neutralize therapeutic insulin but at the same time they exert an insulin-sparing action by improvement of diabetes control. Occasionally the latter effect may abolish the correlation between diabetes control and beta-cell functional capacity.

Measurement of insulin in human sera using a new RIA kit. 2. Determination of free and total insulin--correlations to insulin antibody levels.

Using the micro-scale modification of a newly developed RIA kit for insulin, we established methods for the determination of free and total insulin in serum of insulin-treated diabetics. Precipitation with polyethylene glycol 6000 or acid alcohol extraction of sera was carried out to remove or to dissociate antibody-bound insulin. Both assays permit precise and accurate measurement of either serum insulin fraction. In 50 diabetic sera with tracer insulin binding of 0-97%, free (after equilibration of the sera at 37 degrees C) and total insulin levels as well as insulin antibody binding parameters were determined. There was a good correlation of free to total insulin levels with maximally 10-fold higher values of total insulin. Both free and total insulin were found to be correlated with the ability of the serum to bind insulin. In detail, binding affinities (i.e. the reciprocal of equilibrium dissociation constants) and binding site concentrations were evaluated which were shown to be positively correlated with free and total insulin levels as well. From these data we conclude that insulin antibodies in the serum may accumulate therapeutic insulin and function as a depot for delivering insulin in insulinopenic episodes (Keilacker et al., 1982 and 1986).

Assessment of long-term immunological and pulmonary safety of inhaled human insulin with up to 24 months of continuous therapy

ABSTRACTBackground: This study was performed to characterize the long-term safety and efficacy of inhaled human insulin (EXU; Exubera (insulin human [rDNA origin]) Inhalation Powder).* Pfizer Inc, New York, NY, USAScope: Patients with type 1 or type 2 diabetes (N = 1290) who had successfully completed one of six controlled EXU open-label trials elected to receive open-label treatment with EXU for up to 3 years, after which they were randomized to discontinue EXU or to continue therapy for 6 months, then discontinue. Immunologic safety was assessed by insulin antibody (IAb) binding, and pulmonary safety was assessed by tests for forced expiratory volume in 1 second (FEV1) and carbon monoxide diffusing capacity (DLCO). In addition, changes over time in IAbs were compared with changes in FEV1, DLCO, hypoglycemia, and efficacy.Findings: Antibody binding increased in patients with either type 1 or type 2 diabetes after initiation of EXU and plateaued within 6–12 months (increases were higher in patients with type 1 diabetes than in patients with type 2 diabetes). Decreases in FEV1 occurred primarily during the first 3–6 months of EXU therapy. Among adult patients in the All Subjects set, the mean (± SE) annualized rate of decline in FEV1 was −0.053 ± 0.007 liters/year (95% CI, −0.065, −0.040) in adult patients with type 1 diabetes, and −0.076 ± 0.005 liters/year (95% CI, −0.085, −0.067) in patients with type 2 diabetes. Changes in DLCO occurred primarily during the first 3–6 months of EXU therapy. Among adult patients, in the All Subjects set, the mean (± SE) annual decline in DLCO was −0.738 ± 0.097 mL/min/mmHg/year (95% CI, −0.927, −0.548) and −0.688 ± 0.082 mL/min/mmHg/year (95% CI, −0.849, −0.527) in patients with type 1 and type 2 diabetes, respectively.Antibody binding did not correlate with changes in glycemic control, lung function, dose, or hypoglycemia. Following discontinuation of EXU, IAbs decreased to near baseline levels.Conclusion: These results are consistent with other trials showing long-term maintenance of safety and efficacy of EXU despite insulin antibody formation and small treatment group differences in pulmonary function. A limitation of the study was the lack of a comparator therapy.

Long-term tolerability of inhaled human insulin (Exubera®) in patients with poorly controlled type 2 diabetes

Inhaled human insulin (Exubera; EXU) has shown encouraging tolerability in short-term trials. We evaluated the safety profile of EXU after long-term exposure. In two, open-label, 2-year studies patients poorly controlled on a sulphonylurea were randomised to adjunctive EXU or metformin (study 1) and patients poorly controlled on metformin were randomised to adjunctive EXU or the sulphonylurea, glibenclamide (study 2). The studies included 446 (study 1) and 476 (study 2) patients with type 2 diabetes, no clinically significant respiratory disease and glycosylated haemoglobin (HbA(1c)) levels of 8-12%. Main outcome measures were pulmonary function tests and insulin antibody assays. A total of 109 patients (study 1) and 195 patients (study 2) completed 104 weeks treatment. In both studies, small treatment group differences in change from baseline forced expiratory volume in 1 s were greatest at 6 months (first time-point measured) and less at later visits, and reversed on treatment discontinuation. At 2 years, differences in mean changes were -0.10 and -0.01 l in studies 1 and 2, respectively, and -0.04 l for the pooled studies. There was no discernable effect of long-term EXU therapy on pulmonary gas exchange. Insulin antibody binding reached a plateau at 6 months and did not correlate with HbA(1c) or lung function changes. Glycaemic control was maintained over 2 years. Exubera was well tolerated during long-term use. Pulmonary function changes compared with comparator groups were small, non-progressive and reversed upon treatment discontinuation. Importantly, rates of lung function change were indistinguishable between EXU and comparator after 6 months of therapy.

Hypoglycemia due to an Insulin Binding Antibody in a Patient with an IgA-κ Myeloma

Autoantibodies to insulin have been described to cause spontaneous hypoglycemia in nondiabetic subjects. There have been occasional reports of spontaneous hypoglycemia due to monoclonal anti-insulin antibodies. We present the first report of a patient with an IgA-kappa myeloma in whom frequent hypoglycemia resulted from the ability of the monoclonal IgA-kappa to bind insulin. The aim of this study was to describe the occurrence of profound hypoglycemia in a patient with IgA-kappa myeloma, characterize biochemically the nature of the IgA:insulin complex present, and place this case in the context of the published literature on hypoglycemia resulting from autoantibodies to insulin. A case study was performed. A single case of profound hypoglycemia associated with IgA-kappa myeloma was studied. There were no interventions. A case study was performed. Polyethylene glycol precipitation and gel filtration chromatography were used to demonstrate high-molecular weight insulin immunoreactivity in the patient's plasma. This was characterized as an insulin binding IgA-kappa paraprotein present at 4200 mg/dl (42 g/liter) with a relatively high insulin dissociation constant of 0.32 microm/liter using radiolabelled insulin binding studies. We present the first case of hypoglycemia due to IgA binding insulin antibodies in a patient with an IgA-kappa paraprotein myeloma. The hypoglycemia was associated with high-plasma insulin levels and relatively low C-peptide levels. A plausible mechanism for the hypoglycemia is the delayed clearance of insulin. This case broadens the spectrum of monoclonal gammopathies that have been associated with anti-insulin reactivity and spontaneous hypoglycemia.

Clinical Experience With U-500 Regular Insulin in Obese, Markedly Insulin-Resistant Type 2 Diabetic Patients

On a clinical basis, severe insulin resistance is defined as a situation in which a patient requires >200 units of insulin daily for >2 days (1). This definition was determined >50 years ago, when it was erroneously believed that the human pancreas secreted ∼200 units of insulin a day. Although it is now known that the normal pancreas secretes only 20–40 units of insulin a day, this clinical definition is helpful because it delineates a very small group of patients, many with a number of unusual underlying problems. In adults, the conditions associated with clinical insulin resistance are gross obesity, severe infection, Cushing’s syndrome, acromegaly, hemochromatosis, lipodystrophic diabetes, genetic insulin receptor abnormalities, insulin receptor antibodies, Werner’s syndrome (adult form of progeria), insulin degradation at the injection site, and high titers of IgG insulin binding antibodies (immune mediated). Gross obesity is by far the most common condition. Although a recent review (2) discussed the use of U-500 regular insulin in states of severe insulin resistance, no detailed description of how to start and adjust doses of this concentrated form of insulin was given. This article provides a treatment algorithm for the use of U-500 regular insulin and summarizes our experience with obese, markedly insulin-resistant type 2 diabetic patients. …

Longitudinal epitope analysis of insulin-binding antibodies in type 1 diabetes

Autoantibodies to insulin (IAA) are one of the first markers of the autoimmune process leading to type 1 diabetes (T1D). While other autoantibodies in T1D have been studied extensively, relatively little is known about IAA and their binding specificities, especially after insulin treatment is initiated. We hypothesize that insulin antibodies (IA) that develop upon initiation of insulin treatment differ in their epitope specificities from IAA. We analysed insulin antibody binding specificities in longitudinal samples of T1D patients (n = 49). Samples were taken at clinical diagnosis of disease and after insulin treatment was initiated. The epitope specificities were analysed using recombinant Fab (rFab) derived from insulin-specific monoclonal antibodies AE9D6 and CG7C7. Binding of radiolabelled insulin by samples taken at onset of the disease was significantly reduced in the presence of rFab CG7C7 and AE9D6. rFab AE9D6 competed sera binding to insulin significantly better than rFab CG7C7 (P = 0.02). Binding to the AE9D6-defined epitope in the initial sample was correlated inversely with age at onset (P = 0.005). The binding to the AE9D6-defined epitope increased significantly (P < 0.0001) after 3 months of insulin treatment. Binding to the CG7C7-defined epitope did not change during the analysed period of 12 months. We conclude that epitopes recognized by insulin binding antibodies can be identified using monoclonal insulin-specific rFab as competitors. Using this approach we observed that insulin treatment is accompanied by a change in epitope specificities in the emerging IA.

An Open, Randomized, Parallel-Group Study to Compare the Efficacy and Safety Profile of Inhaled Human Insulin (Exubera) With Glibenclamide as Adjunctive Therapy in Patients With Type 2 Diabetes Poorly Controlled on Metformin

To compare the efficacy and safety profile of adding inhaled human insulin (INH) (Exubera) or glibenclamide to metformin monotherapy in patients with poorly controlled type 2 diabetes. We conducted an open-label, parallel, 24-week multicenter trial. Patients uncontrolled on metformin were randomized to adjunctive INH (n = 243) or glibenclamide (n = 233). Before randomization, patients were divided into two HbA(1c) (A1C) arms: > or =8 to < or =9.5% (moderately high) and >9.5 to < or =12% (very high). The primary efficacy end point was A1C change from baseline. Mean adjusted A1C changes from baseline were -2.03 and -1.88% in the INH and glibenclamide groups, respectively; between-treatment difference -0.17% (95% CI -0.34 to 0.01; P = 0.058), consistent with the noninferiority criterion. In the A1C >9.5% arm, inhaled insulin demonstrated a significantly greater reduction in A1C than glibenclamide, between-treatment difference -0.37% (-0.62 to -0.12; P = 0.004). In the A1C < or =9.5% arm, between-treatment difference was 0.04% (-0.19 to 0.27; P = 0.733). Hypoglycemia (events per subject-month) was greater with INH (0.18) than glibenclamide (0.08), risk ratio 2.24 (1.58-3.16), but there were no associated discontinuations. Other adverse events, except increased cough in the INH group, were similar. At week 24, changes from baseline in pulmonary function parameters were small. Insulin antibody binding increased more with INH but did not have any associated clinical manifestations. In patients with type 2 diabetes poorly controlled on metformin, adding INH or glibenclamide was similarly effective in improving glycemic control, and both were well tolerated. A predefined subgroup with very high A1C (>9.5%) was more effectively treated with the addition of INH.