Kathy Traianedes

Obesity, Diabetes, and Hyperlipidemia in a Central Australian Aboriginal Community With a Long History of Acculturation

Objective— To determine the age- and sex-specific prevalence of diabetes and to examine associations between related anthropometric and metabolic abnormalities in an Aboriginal community in central Australia with a long history of acculturation. Research Design and Methods— We used a cross-sectional survey of 353 adults > 15 yr of age (87% response rate) and measured the following parameters: weight, height, circumferences of waist and hips; glucose, insulin, cholesterol, triglyceride, and high-density lipoprotein cholesterol in fasting plasma; and plasma glucose and insulin 2 h after 75 g oral glucose. Results— The prevalence of diabetes was 29.6% in survey participants > 35 yr of age and 5.3% in those < 35 yr of age. Impaired glucose tolerance also occurred with higher frequency in those > 35 yr of age (14.8 vs. 4.7%). Of those > 35 yr of age, 75% of the women and 51% of the men were overweight or obese, with a body mass index ≥ 25 kg/m2. A large insulin response to oral glucose was evident, with the upper tertile of the 2-h insulin response six times higher than the lower tertile (113 ± 43 vs. 19 ± 8 mU/L). Hyperinsulinemia showed a strong, positive association with impaired glucose tolerance, body mass index, waist-to-hip ratio, cholesterol, and triglyceride levels and a negative association with high-density lipoprotein cholesterol levels. Cholesterol levels were on average 0.5 mM higher in men than in women. Deteriorations in carbohydrate and lipid metabolism occurred before 40 yr of age: diabetes, body mass index, waist-to-hip ratio, and fasting triglycerides and cholesterol concentrations peaked and high-density lipoprotein cholesterol concentrations reached their nadir at the end of the fourth decade. Conclusions— These data suggest that any intervention programs developed to prevent or reduce diabetes prevalence in this population should be targeted at adolescents and young adults.

Impaired Glucose Tolerance, Hyperinsulinemia, and Hypertriglyceridemia in Australian Aborigines From the Desert

A cross section of adult full-blooded Aborigines from three small isolated communities in the desert region of northwest Australia was surveyed for diabetes, impaired glucose tolerance (IGT), insulin levels, and lipoprotein lipids. Sixty-three men and 86 women from a total adult population of 330 were tested. Of the people tested, 67.6% had normal glucose tolerance, 25% had IGT, and 7.4% had diabetes. Both diabetes and IGT were strongly age related. Fasting insulin levels and insulin responses to oral glucose (elevation above basal) were elevated. Although fasting insulin rose with age, insulin response did not rise after adjustment for body mass index (BMI). Plasma triglyceride levels were high, particularly in men >35 yr old (3.13 ± 0.32 mM), but cholesterol levels were not elevated. Multiple regression analysis of fasting glucose, 2-h glucose, plasma triglyceride, fasting insulin, and insulin response for the nondiabetic subjects revealed 7) BMI was an independent risk factor for elevated 2-h glucose levels in women but not in men and was strongly related to fasting insulin concentrations in both genders; 2) fasting insulin concentration was an independent risk factor for increases in fasting glucose, insulin response, and triglyceride levels; 3) insulin response was related to the 2-h glucose level; 4) fasting and 2-h glucose levels and fasting insulin and triglyceride concentrations all rose with age in both genders, with the rate of increase generally greater in men. The most striking difference between these desert Aborigines and previously studied coastal Aborigines from the same geographical region was the significantly higher insulin response. It is possible that the more severe hyperinsulinemia in the desert Aborigines may indicate a greater degree of susceptibility to type II diabetes than in the coastal Aborigines as the duration of urbanization increases.

Low-Dose Acarbose Improves Glycemic Control in NIDDM Patients Without Changes in Insulin Sensitivity

OBJECTIVE To examine the impact on metabolic control in NIDDM patients of the alpha-glucosidase inhibitor, acarbose, when administered at a low dose in powdered form. RESEARCH DESIGN AND METHODS Six subjects were recruited for a double-blind cross-over trial using 25 mg powdered acarbose and a placebo 3 times a day with meals for 3 mo. In addition to parameters of diabetes control and body weight, glucose turnover and insulin sensitivity were measured with the hyperinsulinemic/euglycemic clamp technique combined with tracer kinetics. RESULTS None of the subjects showed significant changes in FPG levels or body weight either on the 3-mo course of acarbose or placebo. HbA1c fell significantly from 10.6 ± 1.0 to 9.4 ± 1.3% (P = 0.05) during treatment with acarbose but failed to change on placebo (10.1 ± 1.0 to 11.1 ± 2.0%; P = 0.36). Basal HGP and glucose utilization were unchanged during either of the treatment periods, and hyperinsulinemia produced a similar degree of suppression of HGP before and after each treatment. At a physiological concentration, insulin failed to stimulate glucose clearance in these diabetic patients, and no improvement was seen with acarbose treatment. No changes in plasma lipids or lipoprotein profiles were demonstrated after 3 mo on acarbose. In acute studies, it was shown that administration of acarbose at a dose of 25 mg powder per meal significantly decreased the postprandial glycemic excursion. CONCLUSIONS When administered in the powdered form at the low dose of 25 mg 3 times/day with meals over 3 mo, acarbose was well tolerated by the NIDDM patients and was without side effects. It improved glycemic control by reducing postprandial hyperglycemia, but had no effect on glucose turnover, insulin sensitivity, or lipid profile.

Abnormal Glucose Tolerance and Other Coronary Heart Disease Risk Factors in an Isolated Aboriginal Community in Central Australia

OBJECTIVE To determine the age- and sex-specific prevalence of diabetes, impaired glucose tolerance (IGT), and coronary heart disease risk factors in a remote central Australian Aboriginal community maintaining some degree of traditional lifestyle, living in homeland communities on their ancestral land. RESEARCH DESIGN AND METHODS A cross-sectional survey of 437 subjects ≥ 15 years of age (189 men, 248 women), representing 80% of the adult population residing in the community at the time of the survey, was performed and the following parameters measured: BMI, glucose tolerance, circulating insulin and lipids, and blood pressure. RESULTS The mean BMI for this population was 22.9 ± 4.8 kg/m2. The prevalence of diabetes in the age group of 15–34 years (103 men and 140 women) was 2 and 6% for men and women, respectively. In the 35-years-and-older age group (86 men and 108 women), diabetes prevalence was 19 and 13% for men and women, respectively. Over half the diabetic subjects did not exhibit fasting hyperglycemia. IGT occurred in 8 and 15% of younger men and women, respectively, and in 17 and 32% of older men and women, respectively. Smoking was common among men (53% current smokers) but rare among women (2% current smokers). The prevalence of hypercholesterolemia, hypertriglyceridemia, hypertension, and overweight rose with increasing degrees of glucose intolerance. The two communities adjacent to the only store in the area had a higher prevalence of abnormal glucose tolerance than did the more remote homeland communities (odds ratio for abnormal glucose tolerance: 2.92; 95% CI 1.51−5.63). CONCLUSIONS Despite their relative leanness, this Aboriginal population exhibited relatively high prevalences of IGT and diabetes without fasting hyperglycemia. The data suggest a protective effect of a decentralized mode of living, as opposed to a more urbanized lifestyle, on the occurrence of glucose intolerance. Abnormal lipid profiles (particularly high triglycerides and low HDL cholesterol) and the high prevalence of smoking in men indicated a high-risk profile for coronary heart disease in this population.

Diabetes, Hyperinsulinemia, and Hyperlipidemia in Small Aboriginal Community in Northern Australia

A small rural Aboriginal community in northern Australia was surveyed for diabetes, impaired glucose tolerance (IGT), hyperinsulinemia, and lipid levels. Of the 122 adults >17 yr of age who participated (95% response rate), 11.5% had diabetes, 7.4% had IGT, and the remaining 81.1% had normal glucose tolerance. Both diabetes and IGT were strongly age related. This high frequency of diabetes occurred, despite the population being relatively lean. Although the body mass index (BMI) increased with age in both men and women, only 25% of the population overall had BMI >25 kg/m2. There were wide ranges of insulin responses to glucose, with the upper fertile of 2-h insulin levels being more than seven times higher than the lower fertile (144 ± 13 vs. 19 ± 1 mLI/L). Hyperinsulinemia was associated with IGT, elevated triglycerides, and lower high-density lipoprotein cholesterol levels. Lipid abnormalities were much more frequent among men than women. Cholesterol levels were an average of 0.55 mM higher and triglycerides an average of 1.05 mM higher in men than in women, and both increased with age. In conclusion, this small isolated Aboriginal population from northern Australia had an unexpectedly high frequency of diabetes (in view of their relative leanness) in association with a high frequency of metabolic abnormalities indicative of insulin resistance (hyperinsulinemia, IGT, hypertriglyceridemia).

Identification of early metabolic defects in diabetes-prone Australian Aborigines

The aim of the present study was to identify in young, diabetes-prone subjects the early abnormalities which may predispose to the development of type 2 diabetes. We studied 10 full-blood Australian Aborigines all of whom had a family history of diabetes and who were from an urbanised community with a high prevalence of this disorder. They were compared to 10 age- and body-mass-index-matched Caucasian controls with no family history of diabetes. Glucose kinetics were measured basally and following an oral glucose load. Fasting plasma glucose was equal in the two groups, but 2 h following the 75 g glucose load, the Aboriginal subjects had higher glycaemia than the controls (P less than 0.01). Insulinaemia was higher in the Aborigines both basally and following the glucose drink (P less than 0.05). Despite the hyperinsulinaemia, hepatic glucose production was higher in the Aboriginal subjects (P less than 0.01), while metabolic clearance rate was lower. It is concluded that in young Australian Aborigines with a strong family history of type 2 diabetes, both hepatic and peripheral insulin resistance are early abnormalities.

A high-fat diet worsens metabolic control in streptozotocin-treated rats by increasing hepatic glucose production.

The aim of this study was to determine the mechanism by which a high-fat diet exacerbates the diabetes produced by a low dose of streptozotocin (STZ). The glucose clamp technique was used to determine hepatic glucose production (HGP) and the disappearance rate (Rd) of glucose, basally and during insulin infusions of 1.0 and 3.0 mU/kg/min in control of STZ-treated rats fed either a low-fat or high-fat diet. Fasting plasma glucose in the high fat-STZ (HFS) group was significantly higher than in any of the other groups: low fat-STZ (LFS), high-fat controls (HFC), or low-fat controls (LFC) (18.1 +/- 1.6 v 8.1 +/- 0.8 mmol/L, P less than .001; 6.0 +/- 0.2 mmol/L, P less than .001; 5.4 +/- 0.1 mmol/L, P less than .001, respectively). Basal HGP was markedly higher in the HFS group compared with each of the other three groups (98.8 +/- 5.9 v 61.4 +/- 3.7, P less than .001; 42.9 +/- 1.6, P less than .001; 39.6 +/- 1.3 mumol/kg/min, P less than .001; HFS v LFS, HFC, and LFC, respectively). Following insulin infusion, no differences were observed in HGP between the LFC and LFS groups at either insulin dose. However, HGP was not suppressed to control levels in either of the high-fat diet groups, and this defect was more marked in the HFS group. It is concluded that a high-fat diet exacerbates mild STZ diabetes primarily by increasing HGP.