Diabetes of a predominant maturity-onset type has been identified as being up to ten times more prevalent in South Australian Aborigines than in Caucasians. On the evidence provided, nutritional status and obesity are thought to be dominant in the aetiology of the hyperglycaemia, although relative hyperinsulinaemia in full blood Aborigines suggests a significant racial genetic effect. It is suggested on these and other grounds that the diabetic genotype may represent a factor of previous survival advantage to the Aboriginal, now rendered deleterious by urbanization. The degree of hyperglycaemia, and its association with hyperlipidaemia, obesity, retinal arteriovenous changes and abnormal electrocardiographic findings, accentuates the significance of the diabetes, and underlines the serious need for ongoing nutritional education in these communities.
Blood pressure measurements were recorded in 522 adults and 141 10-19 year-old full and part blood Aborigines in five communities. The means for systolic and diastolic blood pressures at 40 years were close to those reported for Europeans, although below this age, values tended to be lower, and above 40 years tended to be higher than those reported in the Tecumseh study. Hypertension, as defined by the Princeton criteria, was present in 29%, more often in the men (1-6 to 1-0), and eight subjects satisfied the criteria for hypertensive heart disease (HHD). 522 electrocardiograms were recorded on adult subjects at five Aboriginal communities and classified according to categories of the Minnesota code. Of the 210 abnormalities observed, minor T wave inversions and minor S-T segment depression were the most commonly encountered, and were more frequent in female subjects. Q wave changes typical of myocardial infarction was found in 5% of the tracings and occurred mainly in older men. If hypertension and certain ECG codes are assumed to be "risk factors" for the development of clinical ischaemic heart disease (IHD), the urbanized Aboriginal had a higher prevalence compared with Caucasian subjects of the Busselton study. "Probable" and "suspect" ECG changes of IHD, although mainly in the older subjects, were found to be associated with hyperglycaemia, as recognised in Western society. It is postulated that urbanized Aborigines are prone to cardiovascular degenerative disease to a similar or possibly larger extent than Caucasians.
Eye examinations were carried out a four Aboriginal reserves. Of 361 Aboriginal adults tested, 64 had a visual defect (visual acuity of 6/9 or worse) in each eye, a prevalence of 18%, with an additional 79 (22%) with a similar loss of acuity in one eye only; these were more frequently seen at the urbanized reserve of Koonibba. Only one full blood Aboriginal child within the less urbanized communities had a reduced visual acuity, whereas seven (10%) part blood children at a more urbanized reserve had reduced vision in both eyes, with a further nine (13%) in one eye only, not unlike figures quoted for South Australian school children. Vascular changes in the fundus oculi were observed and occurred more often when hypertension and/or hyperglycaemia were present. They consisted of arteriovenous crossing changes (26%), swelling of the retinal veins (3%) and altered light reflex (41%) and were not infrequently seen in the younger adult (20% of adults under 30 years had AV crossing changes and 46% had widened light streak). Analysis suggests that, although hypertension and hyperglycaemia are related to retinal vascular changes, other factors, as yet unidentified, are present in the Aboriginal population under consideration.
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