Elevation of IgA levels in the non-insulin-dependent (type II) diabetic patient

Serum immunoglobulin (G, A, M) levels were performed on 66 patients with non-insulin-dependent (type II) diabetes mellitus (NIDDM). When compared with 30 age-matched normal controls and 32 hospitalized controls there was no significant difference between the mean IgG and IgM levels. The IgA levels were significantly higher (P less than 0.005) in the diabetic group when compared with both control groups. This is true regardless of age, sex, duration of disease, and type of treatment (insulin/diet or oral hypoglycemic agents and/or diet). Thirty-six percent of the diabetic patients' IgA levels exceeded the mean +/- 2 SD of the normal control group. There were no significant differences in immunoglobulin levels between insulin-treated and non-insulin-treated diabetic groups. Since diabetic patients may have a number of secondary diseases, attempts were made to correlate the most common of these (acute and/or chronic bacterial infections, hypertension, arteriosclerotic heart disease, and diabetic neuropathy) with elevated IgA levels. Only IgA levels of diabetic patients with infections versus diabetic patients without infections were significantly different (P less than 0.05). However, IgA levels of uninfected diabetic patients remained significantly higher than those of normal controls (P less than 0.005), hospitalized controls (P less than 0.01), and hospitalized controls with bacterial infections (P less than 0.005). Possible reasons for the isolated elevations of IgA are discussed.