Islet cell surface antibodies in diabetes and their possible influence on glucose tolerance

The prevalence of islet cell surface antibodies (ICSA) in patients with insulin-dependent (IDD), noninsulin-dependent (NIDD) or newly-diagnosed diabetes mellitus was studied. The antibodies were present in 14 (27%) of 15 IDD patients below the age of 30 years, and in 11 (12%) of 91 NIDD patients. Among 46 newly-diagnosed diabetic patients, (aged over 30 years), 14 (30%) were antibody-positive and had a fasting blood sugar exceeding 11 mmol glucose. The glucose tolerance after a standardized breakfast decreased in IDD or insulin-treated patients with ICSA compared to patients without antibodies. C-peptide was also lower in patients with circulating ICSA (xi CPR/xi BS during a standardized breakfast test 0.61 +/- 0.30 vs. 1.09 +/- 0.3 in IDD, 1.18 +/- 0.13 vs. 1.46 +/- 0.43 in the patients with insulin treatment). These results suggest that circulating ICSA be also present in some newly-diagnosed patients of over 30 years of age who require insulin treatment and who have an associated decreased glucose tolerance and C-peptide response.