Insulin therapy allergic reactions

M/sce/Zaneows-Allergic reactions. Sodium retention and edema may occur, particularly if previously poor metabolic control is improved by intensified insulin therapy. Antibody production. 

Occasional patients have antibodies to injected insulin, but the significance of the antibodies is minimal. Human insulin therapy has not totally eliminated insulin allergies, although most patients have a local reaction that will dissipate over time. If the allergic reaction does not improve or is systemic, insulin desensitization can be carried out. Protocols for desensitization are available from major insulin manufacturers. While more common in the animal insulin era, lipohypertrophy is still seen in some patients with longstanding type 1 DM. Such patients give their insulin injections in the same site to minimize discomfort. Because insulin absorption from an area of lipohypertrophy is unpredictable, avoidance of injections into these areas is mandatory. 

Insulin is capable of producing allergic reactions through a variety of immunologic mechanisms. A protein molecule, insulin is a complete antigen. Allergic reactions have been reported with beef, pork, and recombinant human insulin, although the frequency of reactions with human insulin appears low. Reactions to insulin may involve the insulin molecule itself or other substances that have been added to insulin (e.g., protamine). Most patients have anti-insulin IgG antibodies after a few months of therapy. 

During the first decade of the insulin era, only an acid solution of an impure form of the hormone was available for therapy. When it became possible to crystallize insulin, the purity, and hence the biological potency, of the hormone improved substantially (Table I). These improvements were mainly achieved by introduction of Ztf+-crystallization (Scott, 1934) and recrystallization methods, the latter based on the observation that insulin recrystallized several times was better tolerated by patients suffering from allergic reactions (Jorpes, 1949). Until the late 1960s, recrystallized insulin was considered to be an essentially pure substance, but the introduction of new analytical methods made it possible to detect the presence of significant amounts of protein impurities by disc electrophoresis (Mirsky and... 

An allergic reaction towards MC insulin has been reported (5 ) in a patient who earlier had shown allergic reactions towards NPH insulin. After 3 weeks of therapy with MC insulin immediate skin reactions developed late reactions were also seen. Direct skin tests and passive cutaneous reactions were negative. Other authors report a positive effect of MC insulin on lipodystrophy (in 6 patients) (d -) and on other allergic reactions (see 7 —9, 10 ), but antibodies could still be demonstrated in the patients concerned, despite the improvement which they exhibited. 

Results of therapeutic approach in patients with systemic insulin allergy are given by Mattson et al. (12). Desensitization was successful in 12 patients who needed insulin. In these patients insulin therapy had been stopped because of allergic reactions to insulin, often many years previously. Eight patients had elevated IgE levels at the start of therapy. With desensitization IgE levels declined rapidly. 

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