A comparative study of insulin resistance for Saudi and Caucasian subjects across a range of glycaemic categories

Aim: Saudi and Caucasian subjects, matched for adiposity, and of differing glycaemic status were compared using several insulin sensitivity indices and to also to assess insulin, glucose and insulin-like growth factor binding protein-1 (IGFBP-1) responses to intravenous glucose. Methods: Subjects with normal glucose tolerance (NGT; n = 24), impaired fasting glucose (IFG; n = 12), impaired glucose tolerance (IGT; n = 12), and type 2 diabetes (DM; n = 13) were recruited from Saudi (n = 33) and Caucasian (n = 28) populations. All had specimens taken in the context of a standard oral glucose tolerance test at their first visit and had the insulin sensitivity parameter (Si) determined by frequently-sampled intravenous glucose tolerance test (FSIVGTT) at a second visit. Results: Saudis in the NGT and pooled glucose intolerance categories had significantly higher diastolic blood pressure (p < 0.001, p < 0.05 respectively) and HbA1c (p < 0.01, p < 0.05 respectively) compared to Caucasians. Caucasians in the NGT category had significantly higher Si, fasting and 2 h IGFBP-1 (p < 0.01, p < 0.05 and p < 0.01 respectively) compared to Saudis. Two hours following oral or intravenous glucose serum IGFBP-1 decreased to 44% (p < 0.001) and 50% (p < 0.05) of baseline levels respectively. Conclusions: Our data suggest that adult Saudis with normal glucose tolerance appear to be more insulin resistant than Caucasians matched for adiposity. In normal individuals at 2 h the IGFBP-1 level will be about half the baseline level regardless of the route of glucose administration. (C) 2009 Diabetes India. Published by Elsevier Ltd. All rights reserved.