1. ¹Endocrine and Diabetes Unit, Department of Internal Medicine, Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1, Cameroon
2. ²Department of Endocrinology and Diabetes, Saint-Louis Hospital, Paris 10, France
3. ³Department of Haematology and Cancerology, Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1, Cameroon
4. ⁴Department of Biochemistry and Physiological Sciences, Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1, Cameroon

Correspondence: Professor J-C N Mbanya, Endocrine and Diabetes Unit, Department of Internal Medicine, University of Yaoundé 1, PO Box 8046 Yaoundé, Cameroon. E-mail: jean-claude.mbanya@camnet.cm

Guarantor: Professor J-CN Mbanya.

Contributors: JCM, JM, ES, DM, and JN contributed to the design of the study and the preparation of the manuscript. JCM, JM and ES carried out the clinical study and JM, DM and JN carried out the biological assays.

Received 20 January 2002; Revised 13 May 2002.

Abstract

Objective: To evaluate glycaemic and insulinaemic index and in vitro digestibility of the five most common Cameroonian mixed meals consisting of rice+tomato soup (diet A), bean stew+plantains (B), foofoo corn+ndolé (C), yams+groundnut soup (D), and koki beans+cassava (E).

Subjects: Ten healthy non-obese volunteers, aged 19–31 y, with no family history of diabetes or hypertension.

Interventions: A 75 g oral glucose tolerance test followed by the eating of the test diets with carbohydrate content standardized to 75 g every 4 days with blood samples taken at 0, 15, 30, 60, 120 and 180 min. In vitro digestion of each diet according to Brand's protocol.

Main outcome measures: Plasma glucose, cholesterol, triglyceride, insulin and C-peptide, with calculation of glycaemic and insulinaemic index defined as the area under the glucose and insulin response curve after consumption of a test food divided by the area under the curve after consumption of a control food containing the same amount of carbohydrate, and digestibility index.

Results: Glycaemic index (GI) varied from 34.1 (diet C) to 52.0% (diet E) with no statistical difference between the diets, and insulinaemic index varied significantly from 40.2% (C) to 70.9% (A) (P=0.03). The digestibility index varied from 18.9 (C) to 60.8% (A) (P<0.0001), and did not correlate with glycaemic or insulinaemic indices. However, carbohydrate content correlated with GI (r=0.83; P=0.04), digestibility index (r=-0.70; P<0.01), and insulinaemic index (r=0.91; P<0.01). Plasma C-peptide and plasma lipids showed little difference over 180 min following the ingestion of each meal.

Conclusions: Glycaemic index of these African mixed meals are relatively low and might not be predicted by in vitro digestibility index.