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

Abstract

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.