High prevalence of abnormal glucose tolerance and metabolic disturbances in first degree relatives of NIDDM patients. A study in Catalonia, a mediterranean community

Our study aimed to analyse clinical and metabolic characteristics of first degree relatives of patients with non-insulin-dependent diabetes mellitus (NIDDM) in Catalonia. Two hundred and five subjects (39.8 +/- 14.2 year-old, 61% women) were included in the study. An oral glucose tolerance test (OGTT) was performed, obtaining basal plasma glucose and insulin, in order to calculate, %B (HOMA beta cell function) and %S (HOMA insulin sensitivity). A 30.7% of subjects showed an abnormal glucose tolerance, either as impaired glucose tolerance (IGT) (20.5%) or as NIDDM (10.2%). Glycaemia after the OGTT (120 min) was independently determined by fasting glycaemia and age (R-2 = 0.50; P < 0.001). As expected, subjects with normal glucose tolerance (NGT) were significantly younger than IGT and NIDDM subjects. The relatives with IGT and NIDDM display more features of syndrome-X when compared to NGT. Likewise, NGT relatives were less insulin sensitive and their basal insulin levels were higher when compared with a control group of subjects without familial history of NIDDM (log %S, 3.6 +/- 0.4 vs. 3.9 +/- 0.4; P = 0.000; log-insulin 2.4 +/- 0.4 vs. 2.1 +/- 0.6 mU/l; P < 0.02). In comparison with the general population, of any age group, NIDDM and IGT were more common in those subjects with a family history of NIDDM. Interestingly, the rates of abnormal glucose tolerance in the 55-64 and > 64 year groups in the general population were similar to those seen in relatives two decades younger. Our study not only confirms a high prevalence of impaired glucose tolerance (IGT and NIDDM) in subjects with a family history of NIDDM, but also that these abnormalities can be detected at a very early age. Globally, this piece of information corroborates that special attention and precocious detection programs should be addressed to relatives of NIDDM patients. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.