Insulin Resistance and Cardiovascular Risk Factors in Adults with Abnormal Glucose Tolerance in Sub-Sahara Africa
Abstract Number: 1001-P
Authors: FELIX K. ASSAH, ULF EKELUND, SOREN BRAGE, EUGENE SOBNGWI, JEAN CLAUDE MBANYA, NICHOLAS J. WAREHAM
Institutions: Cambridge, Great Britain, Yaounde, Cameroon
Results: Impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) are intermediate states in the development of type 2 diabetes (DM), and have been associated with increased prevalence of cardiovascular disease (CVD). We examined insulin resistance/secretion and CVD risk factors in adult Cameroonians with varying degrees of glucose tolerance.
We recruited 199 men and 381 women (mean age [SD] = 37.0 [8.6] and 39.3 [8.6] years) without known DM. Standard anthropometry/clinical measurements and a 75g oral glucose tolerance test were done. Fasting insulin and lipids were also measured. Insulin resistance was assessed using HOMA-IR, and beta cell function using HOMA-B (%).
Using the 2003 American Diabetes Association criteria, 442 (76.2%) subjects had normal glucose tolerance (NGT), 38 (6.6%) had isolated IFG, 55 (9.5%) had isolated IGT and 37 (6.4%) had newly diagnosed DM. HOMA-IR (mean ± SE) was higher in subjects with DM (1.19 ± 0.21), IGT (0.63 ± 0.11) and IFG (0.70 ± 0.11) compared to NGT (0.48 ± 0.02); p<0.05. HOMA-B in IGT group (79.4 ± 10.7 %) was similar to NGT (73.7 ± 2.6), but was lower in IFG (52.4 ± 5.0) and DM (49.3 ± 7.4). Systolic and diastolic blood pressure were higher in IGT (130.1 ± 3.2 and 81.3 ± 2.0 mmHg) compared to NGT (121.2 ± 0.9 and 75.5 ± 0.6), but not in IFG and DM. There was no difference in cholesterol levels, though triglycerides were higher in DM compared to NGT. BMI and waist circumference were higher in all groups compared to NGT (mean difference ∼ 2 kg/m2 and 4cm, respectively). HOMA-IR was higher in women than men (p<0.05 for NGT).
IFG and IGT in this population are characterised by increased insulin resistance, whereas beta cell function is preserved in IGT but not IFG. However, IGT is associated with increased blood pressure. IGT makes up a significant proportion of abnormal glucose tolerance in this population but cannot be identified by fasting blood glucose measurement routinely used in most public health and clinical settings in developing countries. These results raise important concerns about developing and evaluating simple pragmatic models which could be used in screening for IGT in this population.