[Glutamic acid decarboxylase autoantibodies (antiGAD-Ab) in patients with non-insulin dependent diabetes mellitus (NIDDM)].

AIM OF STUDY

To assess the prevalence of markers of autoimmune destruction of pancreatic beta-cells in patients with non-insulin dependent diabetes mellitus (NIDDM).

SUBJECTS

127 hospitalized NIDDM patients subdivided to the following subgroups: non-obese with C-peptide < 0.3 nmol/l (NIDDM-(-)), non-obese with C-peptide > 0.3 nmol/l (NIDDM-(+)), obese with C-peptide < 0.3 nmol/l (NIDDM+(-)) and obese with C-peptide > 0.3 nmol/l (NIDDM2+). METHODS AND MEASURED PARAMETERS: Age, BMI, C-peptide, autoantibodies to glutamic acid decarboxylase (antiGAD-Ab), autoantibodies to islet cells (ICA), markers of specific cellular immunity CD4, CD8, CD19, CD4/CD8, CD4/CD45/RA+, CD4/CD45/RA-, NK (CD16+56), CD3/HLADR, organ specific/non-specific autoantibodies.

RESULTS

AntiGAD-Ab were positive in 5/15 (33.3%) NIDDM-(-), 1/32 (3.1%) NIDDM-(+), 2/9 (22.2%) NIDDM+(-) and in 3/71 (4.2%) NIDDM2+. The positivity of antiGAD-Ab in NIDDM-(-) and NIDDM+(-) was significantly higher (p < 0.05) than in NIDDM-(+) and NIDDM2+.

CONCLUSION

Some patients with manifestation of diabetes in older age initially classified and treated as having NIDDM may have in fact slowly evolving autoimmune insulin-dependent diabetes mellitus (LADA). These patients can be identified by measurement of antiGAD-Ab or other markers (ICA, IA-2) of autoimmune destruction of pancreatic beta-cells (AID). Moreover, in some patients both AID and insulin resistance may coexist in parallel.