Effect of anti-insulin antibodies on glycemic control in insulin treated diabetic patients

Impact of anti-insulin antibodies on islet transplantation outcome: data from the GRAGIL Network

BACKGROUND

In patients with type 1 diabetes, insulin antibodies (IA), altering the pharmacokinetics of circulating insulin, might be associated with high glucose concentration, prolonged hypoglycemia, and higher insulin requirement. The impact of IA on islet transplantation has never been explored. Our aim was to evaluate islet transplantation results at 1 year according to the presence of IA.

METHODS

Our work is a retrospective, case-control study, comparing IA-negative and IA-positive patients among the cohort of patients with type 1 diabetes transplanted within the Swiss-French GRAGIL network between 2003 and 2010.

RESULTS

Data about IA were available for 17 patients. Before islet transplantation, 10 patients (59%) were screened positive for IA. At 12 months after transplantation, IA-positive patients reached insulin independence less frequently than IA-negative patients (cumulative incidence of insulin independence, 22.2% vs. 71.4%; P=0.02); β score was ≥7 in 43% of IA-negative patients versus 0% in IA-positive patients (P=0.022). When comparing IA-positive patients with IA-negative patients, insulin dose was 0.15 U/kg (0.10-0.18 U/kg) versus 0.01 U/kg (0-0.09 U/kg) (P=0.2); HbA1c was 6.1% (5.8%-6.3%) versus 6.1% (5.9%-6.8%) (P=0.16); basal C-peptide level was 460 ρmol/L (350-510 ρmol/L) versus 265 ρmol/L (177-405 ρmol/L) (P=0.28); occurrence of hypoglycemia was 12.5% versus 16.5% (P=0.9); and homeostatic model assessment insulin resistance was 1.25 (1-2.4) versus 0.7 (0.52-0.92) (P=0.01).

CONCLUSION

After islet transplantation, IA-positive patients achieved insulin independence less frequently, exhibiting lower β score and higher homeostatic model assessment insulin resistance compared with IA-negative patients. However, in both groups, islet transplantation restored good glycemic control and drastically reduced hypoglycemia and insulin requirements.

The importance of anti-insulin antibody in patients with type 1 diabetes mellitus treated with continuous subcutaneous insulin infusion or multiple daily insulin injections therapy

To investigate the influence of two insulin administration modalities, continuous subcutaneous insulin infusion (CSII) and multiple daily insulin injections (MDI) therapy with insulin analogues, on the development of insulin antibodies (IAs) in patients with type 1 diabetes mellitus and to assess the impact of IAs on glucose control and hypoglycaemia. 96 patients with type 1 diabetes mellitus treated with CSII (n = 48) or MDI (n = 48) were included in the study. Age, duration of diabetes, A1c, preprandial and postprandial blood glucose and hypoglycaemic events were compared between IA positive and negative patients. IA levels were higher in the CSII group (% 24.6 ± 14.2) than the MDI group (% 13.2 ± 9.9). Duration of diabetes and age were not associated with IA positiveness. While A1c, preprandial blood glucose and the frequency of hypoglycaemic events were similar in two groups, postprandial blood glucose was lower in IA positive group (P = 0.03). Patients with type 1 diabetes mellitus treated with CSII with insulin analogues had higher IA levels when compared to MDI therapy. However, the development of IAs did not impair the glycaemic control.

Animal insulin therapy induces a biased insulin antibody response that persists for years after introduction of human insulin

Administration of exogenous insulin for the treatment of diabetes is often accompanied by the development of insulin antibodies (IA). These antibodies may affect the patient's requirement for insulin by acting as an insulin binding reservoir. The improvement of insulin purification in the 1970s and the development of human recombinant insulin both reduced the incidence of IA and their binding levels. This study investigates the parameters affecting IA frequency and binding levels in a cohort of type 1 diabetes (T1D) patients. All patients were treated with human recombinant insulin. About half of the patients had received animal insulin prior to the introduction of human recombinant insulin. We tested the IA frequency and binding level for all serum samples. IA were further analyzed for their epitope specificity comparing human and porcine insulin binding. We found that T1D patients who received animal insulin in the past show significantly higher IA binding levels as compared to patients treated exclusively with human recombinant insulin (IA binding level of 0.9 and 0.25 index, respectively, P = 0.005). T1D patients who received animal insulin in the past showed a relative bias towards porcine insulin, as compared to T1D patients who were treated with human recombinant insulin exclusively (P < 0.0001). We conclude that IA binding level and epitope specificity are biased by treatment with animal insulin. This bias remains for over 20 years after animal insulin treatment is terminated.

Circulating insulin antibodies: influence of continuous subcutaneous or intraperitoneal insulin infusion, and impact on glucose control

The purification of animal insulin preparations and the use of human recombinant insulin have markedly reduced the incidence, but not completely suppressed, the development of anti-insulin antibodies (IAs). Advances in technologies concerning the mode of delivery of insulin, i.e. continuous subcutaneous insulin infusion (CSII), continuous peritoneal insulin infusion (CPII) and more recently inhaled insulin administration, appear to significantly increase circulating levels of immunoglobulin G (IgG) anti-IAs in diabetic patients. However, the increase is usually moderate and mostly transient as compared to previous observations with poorly purified animal insulin preparations. The clinical impact of these circulating anti-IAs remains unclear. Nevertheless, several studies have suggested that antibodies could retard insulin action, leading to a worsening of postprandial hyperglycaemia and/or serve as a carrier, thus leading to unexpected hypoglycaemia. CPII may be associated with more marked and sustained increase in IAs levels, possibly related to the use of an unstable insulin and the formation of immunogenic aggregates of insulin. The possible clinical consequences of these high levels of IAs remain to be evaluated because a low-glucose morning syndrome or severe insulin resistance with ketone bodies production have been reported in some cases. In conclusion, even if CSII and CPII may promote the development of circulating IAs, this increase does not lead to immunological insulin resistance, compared to that previously described with animal non-purified insulin preparations, and seems to have only marginal influence on blood glucose control or complications in most diabetic patients.

Immunological responses to exogenous insulin

Regardless of purity and origin, therapeutic insulins continue to be immunogenic in humans. However, severe immunological complications occur rarely, and less severe events affect a small minority of patients. Insulin autoantibodies (IAAs) may be detectable in insulin-naive individuals who have a high likelihood of developing type 1 diabetes or in patients who have had viral disorders, have been treated with various drugs, or have autoimmune disorders or paraneoplastic syndromes. This suggests that under certain circumstances, immune tolerance to insulin can be overcome. Factors that can lead to more or less susceptibility to humoral responses to exogenous insulin include the recipient's immune response genes, age, the presence of sufficient circulating autologous insulin, and the site of insulin delivery. Little proof exists, however, that the development of insulin antibodies (IAs) to exogenous insulin therapy affects integrated glucose control, insulin dose requirements, and incidence of hypoglycemia, or contributes to beta-cell failure or to long-term complications of diabetes. Studies in which pregnant women with diabetes were monitored for glycemic control argue against a connection between IAs and fetal risk. Although studies have shown increased levels of immune complexes in patients with diabetic microangiopathic complications, these immune complexes often do not contain insulin or IAs, and insulin administration does not contribute to their formation. The majority of studies have shown no relationship between IAs and diabetic angiopathic complications, including nephropathy, retinopathy, and neuropathy. With the advent of novel insulin formulations and delivery systems, such as insulin pumps and inhaled insulin, examination of these issues is increasingly relevant.

The effect of insulin antibodies on the metabolic action of inhaled and subcutaneous insulin: a prospective randomized pharmacodynamic study

OBJECTIVE

To assess the impact of the development of high- or low-affinity insulin antibodies (IABs) on postprandial glucose tolerance, duration of insulin action, and clinical safety in patients with type 1 diabetes receiving inhaled insulin (Exubera).

RESEARCH DESIGN AND METHODS

This study consisted of a prospective, randomized, open-label, parallel-group trial in which 47 patients with type 1 diabetes received NPH insulin twice daily plus either premeal inhaled insulin (INH group; n = 24) or pre-meal subcutaneous regular insulin (SC group; n = 23) for 24 weeks. Meal challenge and euglycemic clamp studies were performed on consecutive days at baseline, week 12, and week 24. Adverse events were monitored.

RESULTS

For the INH and SC groups, mean (+/-SD) IAB levels were 3.5 +/- 3.9 and 2.6 +/- 4.1 muU/ml at baseline, respectively, compared with 101.4 +/- 140.4 and 4.3 +/- 9.4 microU/ml at week 24. At week 24, the changes from baseline were similar for the INH and SC groups for maximal plasma glucose concentration (C(max)) (adjusted ratio for treatment group difference 0.99 [90% CI 0.95-1.03]), area under the plasma glucose concentration time curve (adjusted ratio for treatment group difference 0.98 [0.88-1.08]), and duration of insulin action (adjusted treatment group difference 29 min [-49 to 108]). No adverse events were attributed to IABs.

CONCLUSIONS

In patients with type 1 diabetes treated with inhaled insulin, development of high- or low-affinity IABs did not impair postprandial glucose tolerance, alter the time-action profile of insulin, or impact tolerability. No clinical relevance of IABs was identified in this study.

Effects of PEG conjugation on insulin properties

The goal of this research was to determine whether the site-specific attachment of poly(ethylene glycol) to insulin could enhance the physical and pharmacological properties of insulin without negatively affecting its biological activity or immunological properties. Electrophilically activated derivatives of low-molecular-weight monomethoxypoly(ethylene glycol) (mPEG) were chemically coupled to insulin via its amino groups at positions phenylalanine-B1 or lysine-B29, with an amide bond being formed between the polymer and protein. The site-specific attachment of mPEG to insulin did not substantially alter insulin's secondary/tertiary structure, self-association behavior, or potency in vivo. However, mPEG attachment did significantly enhance insulin's resistance to aggregation. In addition, the pegylation of insulin almost completely eliminates the resultant conjugate's immunogenicity, allergenicity, and antigenicity. Finally, the conjugates were observed to remain in the systemic circulation for longer periods of time than unmodified insulin after subcutaneous administration.

Prevalence of anti-insulin antibodies and its relation to severe hypoglycaemia in insulin-treated diabetic patients

The prevalence of anti-insulin antibodies (AIABs) and their association with clinical parameters, metabolic control and severe hypoglycaemia were investigated in a geographically defined population of insulin-treated diabetic patients. Eighty per cent of the patients (479) delivered venous blood samples and answered a questionnaire on severe hypoglycaemic problems during a 12-month period. Circulating AIABs were demonstrable in 78% of the patients, being more common among those with type 1 diabetes and in long-duration patients. High levels of AIABs were also more frequent in patients in whom insulin treatment had been initiated prior to the era of highly purified insulins. The AIABs did not correlate to metabolic control, insulin dose or severe hypoglycaemia. It is concluded that AIABs is not a risk factor for severe hypoglycaemia in insulin-treated diabetic patients.

Resistance and allergy to recombinant human insulin

Insulin allergy and antibody-mediated resistance may complicate therapy with animal insulins. We describe a 53-year-old man manifesting both resistance and persistent systemic allergy despite treatment with recombinant human insulin. Insulin resistance and symptoms of allergy appeared in this patient several months after initiating therapy with mixed beef-pork insulin, as is often the case. Symptoms initially improved, but persisted, and then worsened again, despite continuous human insulin therapy. Total insulin-binding capacity by Scatchard analysis, high plasma insulin-binding capacity, and specific anti-insulin antibody levels were consistent with an immunologic form of insulin resistance. Glucocorticoid therapy was required both to reduce allergic findings and to restore glycemic control. Although recently available human insulins may be less immunogenic than animal forms, immune responses to exogenous human insulin still may pose significant clinical problems.