Indices of Insulin Sensitivity and Oral Disposition Index in Adult Nigerians with Sickle Cell Anaemia: A Pilot Study

Aim: To determine indices of insulin sensitivity and oral disposition index (DIo) derived from 30 min of glucose challenge in adults with sickle cell anaemia; a group in whom there is chronic inflammation.
Study Design: Case-controlled study.
Place of Study: Department of Chemical Pathology and Department of Haematology, University of Ibadan/University College Hospital, Ibadan, Nigeria.
Methodology: Twenty five (25) adults with sickle cell anaemia (SCA) in steady state and 25 age, sex and body mass index (BMI) matched healthy individuals with HbAA genotype were recruited into this study. After an overnight fast of about 10 hr, 5 ml of venous blood was obtained from each participant for the determination of plasma glucose and serum insulin. Thereafter, each subject underwent a 75-g oral glucose tolerance test and at 30min, 5ml of venous blood was obtained for the determination of plasma glucose and serum insulin. Serum insulin was determined using ELISA while the plasma glucose was estimated using glucose oxidase method and indices of insulin sensitivity and β-cell function were calculated appropriately. Differences between variables with Gaussian distribution were determined using independent Student’s t-test while Mann-Whitney U was used for the non-Gaussian variables. P-values less than 0.05 were considered significant.
Results: The mean fasting plasma glucose (FPG) was within the normal limit but was significantly lower in subjects with SCA compared with controls. All other indices of insulin sensitivity (insulinogenic index, fasting insulin resistance index, modified Matsuda index of insulin sensitivity and insulin secretion/insulin resistance index) and oral disposition index (DIo) were similar in both groups.
Conclusion: It could be concluded from this study that SCA subjects have a similar insulin sensitivity status with HbAA subjects. This suggests that SCA subjects might not be more predisposed to the development of type 2 diabetes mellitus than those with HbAA despite the chronic inflammation associated with the former.