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Open Access Research article

Fasting insulin sensitivity indices are not better than routine clinical variables at predicting insulin sensitivity among Black Africans: a clamp study in sub-Saharan Africans

Eugene Sobngwi1122*, Andre-Pascal Kengne34, Justin B Echouffo-Tcheugui5, Simeon Choukem67, Joelle Sobngwi-Tambekou8, Eric V Balti29, Mark S Pearce10, Valentin Siaha2, Aissa S Mamdjokam2, Valery Effoe112, Eric Lontchi-Yimagou12, Oliver T Donfack12, Barbara Atogho-Tiedeu12, Philippe Boudou13, Jean-Francois Gautier14 and Jean-Claude Mbanya12

Author Affiliations

1 Department of Internal Medicine, Faculty of Medicine and Biomedical Sciences, University of Yaounde I, Yaounde, Cameroon

2 National Obesity Centre, Yaounde Central Hospital, Yaounde, Cameroon

3 South African Medical Research Council & University of Cape Town, Cape Town, South Africa

4 The George Institute for Global Health, Sydney, Australia

5 Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA

6 Faculty of Health Sciences, University of Buea, Buea, Cameroon

7 Department of Internal Medicine, Douala General Hospital, Douala, Cameroon

8 Centre of Higher Education in Health Sciences, Catholic University of Central Africa, Yaounde, Cameroon

9 Diabetes Research Center, Brussels Free University-(VUB), Brussels, Belgium

10 Institute of Health & Society, Newcastle University, Newcastle upon Tyne, UK

11 Wake Forest Institute for Regenerative Medicine, Wake Forest University, Winston-Salem, North Carolina, USA

12 Laboratory of Molecular Medicine and Metabolism, Biotechnology Centre, Nkolbisson, University of Yaounde 1, Yaounde, Cameroon

13 Unit of Transfer in Molecular Oncology and Hormonology, Saint-Louis University Hospital, Assistance Publique - Hôpitaux de Paris, Paris, France

14 Department of Diabetes and Endocrinology, Saint-Louis University Hospital, Assistance Publique - Hôpitaux de Paris, University Paris-Diderot Paris-7, Paris, France

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BMC Endocrine Disorders 2014, 14:65  doi:10.1186/1472-6823-14-65

Published: 9 August 2014

Abstract

Background

We aimed to evaluate the predictive utility of common fasting insulin sensitivity indices, and non-laboratory surrogates [BMI, waist circumference (WC) and waist-to-height ratio (WHtR)] in sub-Saharan Africans without diabetes.

Methods

We measured fasting glucose and insulin, and glucose uptake during 80/mU/m2/min euglycemic clamp in 87 Cameroonians (51 men) aged (SD) 34.6 (11.4) years. We derived insulin sensitivity indices including HOMA-IR, quantitative insulin sensitivity check index (QUICKI), fasting insulin resistance index (FIRI) and glucose-to-insulin ratio (GIR). Indices and clinical predictors were compared to clamp using correlation tests, robust linear regressions and agreement of classification by sex-specific thirds.

Results

The mean insulin sensitivity was M = 10.5 ± 3.2 mg/kg/min. Classification across thirds of insulin sensitivity by clamp matched with non-laboratory surrogates in 30-48% of participants, and with fasting indices in 27-51%, with kappa statistics ranging from −0.10 to 0.26. Fasting indices correlated significantly with clamp (/r/=0.23-0.30), with GIR performing less well than fasting insulin and HOMA-IR (both p < 0.02). BMI, WC and WHtR were equal or superior to fasting indices (/r/=0.38-0.43). Combinations of fasting indices and clinical predictors explained 25-27% of variation in clamp values.

Conclusion

Fasting insulin sensitivity indices are modest predictors of insulin sensitivity measured by euglycemic clamp, and do not perform better than clinical surrogates in this population.