[Prevalence of diabetes mellitus and glucose tolerance abnormality in Melanesians and subjects of Polynesian descent in the rural areas of New Caledonia and at Ouvea (Loyalty Islands)]. / Prévalence du diabète sucré et de l'anomalie de la tolérance au glucose chez les Mélanésiens et les sujets d'origine polynésienne dans les zones rurales de Nouvelle-Calédonie et à Ouvea (Iles Loyauté).

The screening of different ethnic groups who live in the same natural system have enabled the authors to study interaction between genetic and environmental factors as a part of etiology of diabetes mellitus. In New Caledonian country areas, the prevalences of glucose tolerance abnormality (GTA) and diabetes mellitus (DM) have been higher with people of polynesian descent than with Melanesians. GTA 7.6 p. ct. versus 5.1 p. ct. DM 6.5 p. ct. versus 2.2 p. ct. The prevalence of these combined diseases have been 14 p. ct. with the Polynesians and 7.2 p. ct. with Melanesians. These two ethnic groups have shown mean ages and obesity rates similar enough to lead the authors to deny these two factors a major part in the difference between the ethnic prevalences of DM. Besides, the mean plasmatic glycemia two hours after a dose of glucose and the relative risk of DM and GTA according to age and obesity rate have shown that the slight differences between these groups are not involved in the different prevalences of DM. This inter-ethnic difference may be due to genetic factors. However, some environment linked factors besides obesity (such as diet and daily life activity) may share a major part in this difference.

The prevalence of diabetes mellitus and impaired glucose tolerance in Melanesians and part-Polynesians in rural New Caledonia and Ouvea (Loyalty Islands).

The study of different ethnic groups living in the same physical environment provides the opportunity to examine interaction of genetic and environmental factors in the aetiology of diabetes mellitus. In rural New Caledonia, the prevalence of diabetes was higher in part-Polynesians than in Melanesians: males - 6.6 versus 0.5%; females - 6.3 versus 3.5% respectively. The prevalence of abnormal glucose tolerance (impaired glucose tolerance and diabetes) was 11.5 and 15.7% in part-Polynesian males and females, respectively, and 4.7 and 9.2% in Melanesian males and females. Mean age and degree of obesity in these ethnic groups were sufficiently similar to suggest that these factors played no significant role in the difference in diabetes prevalence. Furthermore, adjustment of relative risk of impaired glucose tolerance and diabetes for age and obesity indicated that the modest differences between groups were not responsible for the observed variation in diabetes prevalence. The differences in prevalence of impaired glucose tolerance and diabetes between Melanesians and part-Polynesians may be genetically determined, although the role of certain environmental factors other than obesity, e.g. differences in physical activity or qualitative aspects of diet, cannot be excluded.