Abdominal obesity and physical inactivity as risk factors for NIDDM and impaired glucose tolerance in Indian, Creole, and Chinese Mauritians

Type of diabetes and waist-hip ratio are important determinants of serum lipoprotein (a) levels in diabetic patients

This cross-sectional study compared serum lipoprotein (a) [Lp(a)] concentrations in type 1 and type 2 diabetic subjects and examined the determinants of Lp(a) concentrations in both types of diabetes. Serum Lp(a) was measured in 26 type 1 and 107 type 2 diabetic patients and 126 non-diabetic controls. HbA(1c), fasting lipids and urinary albumin were also assayed. Lp(a) concentrations were higher in both type 1 and type 2 diabetic patients compared with controls (P<0.0001 and P<0.0001, respectively), and were higher in type 1 than type 2 diabetic patients (P<0.05). Waist-hip ratio (WHR) was an independent determinant of Lp(a) concentrations in both type 1 and type 2 diabetes.

Combined aerobic and resistance exercise improves glycemic control and fitness in type 2 diabetes

We investigated the effect of an 8 week circuit training (CT) program, combining aerobic and resistance exercise, on indices of glycemic control, cardiorespiratory fitness, muscular strength and body composition in 16 subjects (age 52 +/- 2 years) with type 2 diabetes using a prospective randomised crossover protocol. Submaximal exercise heart rate and rate pressure product were significantly lower after training (P<0.05), whilst ventilatory threshold increased (11.8 +/- 0.7 vs 13.8 +/- 0.6 ml kg(-1)min(-1), P<0.001). Muscular strength also increased with training (403 +/- 30 to 456 +/- 31 kg, P<0.001), whilst skinfolds (148.7 +/- 11.5 vs 141.1 +/- 10.7 mm, P<0.05), % body fat (29.5 +/- 1.0 vs 28.7 +/- 1.1%, P<0.05) and waist:hip ratio (99.2 +/- 1.5 vs 97.9 +/- 1.4%, P<0.05) significantly decreased. Concurrently, peak oxygen uptake (P<0.05) and exercise test duration (P<0.001) increased following training, whilst glycated hemoglobin (P<0.05) and fasting blood glucose (P<0.05) decreased. CT is an effective method of training that improved functional capacity, lean body mass, strength and glycemic control in subjects with type 2 diabetes.

Vascular complications in diabetes and their prevention

Diabetes mellitus is increasing throughout the world. Cardiovascular disease (CVD) accounts for up to 80% of excess mortality in this high-risk population. Patients with diabetes have the same CVD risk factors as those people without diabetes. However, these risk factors are much more powerful in diabetic patients. CVD risk is especially high for diabetic women, and premenopausal diabetic women lose all the protection normally afforded to them by female sex hormones. Controlled clinical trials have clearly demonstrated that rigorous treatment of blood pressure, dyslipidemia and platelet hyperaggrebility strikingly reduces CVD risk in diabetic patients. Strategies directed at interrupting the renin-angiotensin system (both tissue and systemic systems) and the use of 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors have proven to be especially beneficial for this high-risk population.

Insulin, insulin-like growth factors and colon cancer: a review of the evidence

Insulin and insulin-like growth factor (IGF) axes are major determinants of proliferation and apoptosis and thus may influence carcinogenesis. In various animal models, modulation of insulin and IGF-1 levels through various means, including direct infusion, energy excess or restriction, genetically induced obesity, dietary quality including fatty acid and sucrose content, inhibition of normal insulin secretion and pharmacologic inhibition of IGF-1, influences colonic carcinogenesis. Human evidence also associates high levels of insulin and IGF-1 with increased risk of colon cancer. Clinical conditions associated with high levels of insulin (noninsulin-dependent diabetes mellitus and hypertriglyceridemia) and IGF-1 (acromegaly) are related to increased risk of colon cancer, and increased circulating concentrations of insulin and IGF-1 are related to a higher risk of colonic neoplasia. Determinants and markers of hyperinsulinemia (physical inactivity, high body mass index, central adiposity) and high IGF-1 levels (tall stature) are also related to higher risk. Many studies indicate that dietary patterns that stimulate insulin resistance or secretion, including high consumption of sucrose, various sources of starch, a high glycemic index and high saturated fatty acid intake, are associated with a higher risk of colon cancer. Although additional environmental and genetic factors affect colon cancer, the incidence of this malignancy was invariably low before the technological advances that rendered sedentary lifestyles and obesity common, and increased availability of highly processed carbohydrates and saturated fatty acids. Efforts to counter these patterns are likely to have the most potential to reduce colon cancer incidence, as well as cardiovascular disease and diabetes mellitus.

Sensitivity and specificity of anthropometrics for the prediction of diabetes in a biracial cohort

OBJECTIVE

To evaluate the ability of body mass index, waist circumference, waist-to-hip ratio, and combinations of these variables to discriminate individuals who will develop diabetes in adulthood.

RESEARCH METHODS AND PROCEDURES

Data were from 45- to 64-year-old men and women who were members of the Atherosclerosis Risk in Communities cohort. The analysis sample consisted of 12,814 African American and white participants who were free of diabetes at baseline. Body mass index, waist circumference, waist-to-hip ratio, and diabetes incidence (defined as one glucose measure > or =126 mg/dL after fasting for at least 8 hours, one nonfasting glucose measure > or =200 mg/dL, and self-report of diabetes or report of taking medication for diabetes).

RESULTS

1515 new cases of diabetes were identified over the 9-year follow-up. Areas under receiver operating characteristic curves ranged from 0.66 to 0.73 for single measures. The curves were smooth, with no indication of a threshold. Waist tended to have the highest receiver operating characteristic statistic in all groups, but differences were small.

DISCUSSION

The three anthropometric indices tested were approximately equivalent in their ability to predict diabetes. Sensitivity and specificities differed among ethnic and gender groups.

Physical activity in aging: changes in patterns and their relationship to health and function

Sedentary behavior is an important risk factor for chronic disease morbidity and mortality in aging. However, there is a limited amount of information on the type and amount of activity needed to promote optimal health and function in older people. The purpose of this review is to describe the change in patterns of habitual physical activity in aging and the relationship of these changes to physical function and selected chronic diseases. We undertook a literature review of large population-based studies of physical activity in older people, and there is encouraging evidence that moderate levels of physical activity may provide protection from certain chronic diseases. Additionally, substantial health effects can be accrued independent of the fitness effects achieved through sustained vigorous activity. Thus, regular participation (i.e., 30 minutes/day on most days of the week) in activities of moderate intensity (such as walking, climbing stairs, biking, or yardwork/gardening), which increase accumulated daily energy expenditure and maintain muscular strength, but may not be of sufficient intensity for improving fitness, should be encouraged in older adults. Public policy should focus on ways of increasing volitional and lifestyle activity in older people, as well as on increasing the availability and accessibility of senior and community center programs for promoting physical activity throughout the life span.

Obesity and sedentary lifestyle: modifiable risk factors for prevention of type 2 diabetes

Over the past 25 years, the prevalence and incidence of type 2 diabetes have increased alarmingly worldwide and across all age, gender, and race/ethnic groups. The high economic costs, resulting from the numerous and severe complications of this disease, as well as the social burden associated with diabetes mellitus, have motivated the pursuit of prevention methods. Recently, clinical and observational studies have demonstrated the adverse effects of obesity and sedentary lifestyle, as well as the benefits of moderate weight loss and related behaviors, including increased levels of physical activity, in maintaining metabolic control and reducing the incidence of type 2 diabetes. The challenge remains to find ways to successfully deliver this message to the communities, and to evaluate the cost-effectiveness of the different delivery approaches.

Glucose intolerance, plasma insulin levels, and colon adenomas in Japanese men

Hyperinsulinemia may be related to colon carcinogenesis. Several studies have suggested that diabetes mellitus is related to increased risk of colon cancer. We examined cross-sectionally the relation of fasting plasma insulin levels and glucose tolerance status to colon adenomas. In a consecutive series of 951 men undergoing total colonoscopy for a health examination at the Japan Self Defense Forces Fukuoka Hospital from April 1998 to August 1999, we identified 233 cases of colon adenomas and 497 controls with normal colonoscopy. Glucose tolerance status was determined by a 75-g oral glucose tolerance test, and subjects were classified as normal, impaired glucose tolerance (IGT) or non-insulin dependent diabetes mellitus (NIDDM). Plasma insulin levels were measured after subjects had fasted overnight. Logistic regression analysis and analysis of covariance was used to control for age and obesity. While plasma insulin levels were unrelated to colon adenomas, NIDDM was associated with a significantly increased risk of colon adenomas. There was no association between IGT and colon adenomas. NIDDM was more strongly associated with proximal colon adenomas. The findings suggest that long-term hyperinsulinemic status associated with NIDDM may increase the risk of colon adenomas, and subsequently of colon cancer.

Determinants of glycated haemoglobin in the general population: associations with diet, alcohol and cigarette smoking

OBJECTIVE

We evaluated cigarette smoking, alcohol intake and consumption of different foods as determinants of glycated haemoglobin in a general population sample.

DESIGN

Cross-sectional survey.

SETTING

England.

SUBJECTS

Representative sample of 15 809 adults aged 16 y and older. Data analysed for 9772 non-diabetic, white European subjects.

MAIN OUTCOME MEASURES

Glycated haemoglobin (GHb). Analyses were adjusted for age, sex, body mass index (BMI), waist-hip circumference ratio, activity level, and educational attainment.

RESULTS

After adjusting for confounding, GHb was 0.277% (95% confidence interval 0.218 to 0.336) higher in current smokers of 20 or more per day, compared with non-smokers. GHb was 0.189% (0.101 to 0.277) lower in those drinking 42 or more units of alcohol per week than in non-drinkers. GHb was not associated with frequency of consumption of pulses, fruit, vegetables and salads, cakes, bread or confectionery. GHb was higher in subjects who took sugar in tea (0.051%, 0.015 to 0.087%) or in coffee (0.069%, 0.034 to 0.105%). GHb was higher in subjects who used solid fat for cooking (0.082%, 0.022 to 0.142%), or who drank whole rather than reduced-fat milk (0.088%, 0.036 to 0.140%), or used butter or hard margarine rather than low-fat spreads (0.075%, 0.029 to 0.121%).

CONCLUSIONS

In the general population, higher GHb may be associated with cigarette smoking, or frequent consumption of fat-containing foods. Consumption of alcohol may be associated with lower GHb.

SPONSORSHIP

None.

A case-control study of physical activity and non-insulin dependent diabetes mellitus (NIDDM). the San Luis Valley Diabetes Study

PURPOSE

The purpose of this study was to examine the association between physical activity and non-insulin dependent diabetes mellitus (NIDDM).

METHODS

We conducted a population-based case-control study in Hispanic and non-Hispanic white men and women, ages 20-74. A total of 167 cases with NIDDM and 1100 controls with normal glucose tolerance were included. All subjects completed an oral glucose tolerance test.

RESULTS

Persons with recently diagnosed NIDDM reported significantly lower levels of physical activity than control subjects. For total metabolic units, the odds ratio for subjects in the highest tertile compared to those in the lowest tertile was 0.60 (95% confidence interval (CI) = 0.37-0.98) after adjusting for age, sex, ethnicity, and family history of diabetes. The adjusted odds ratio for persons reporting high levels of vigorous activity (at least three times per week for 20 minutes) was also less than 1, but was not statistically significant (odds ratio (OR) = 0.73, 95% CI = 0.47-1.14). Similar adjusted odds ratios were observed for high versus low levels of self-assessed work activity (OR = 0.50, 95% CI = 0.34-0.74) and leisure time physical activity (OR = 0.62, 95% CI = 0.44-0.90). Further adjustments for body mass index attenuated the strength of the association between physical activity and NIDDM. This is consistent with the hypothesis that obesity is one consequence of physical inactivity that puts individuals at increased risk for NIDDM. The association of physical activity and NIDDM was stronger in Hispanic than in non-Hispanic white subjects, although this difference was not statistically significant.

CONCLUSIONS

High levels of physical activity are associated with lower odds of NIDDM and this relationship may be stronger in Hispanic subjects.

Ethnicity and glycaemic control are major determinants of diabetic dyslipidaemia in Malaysia

AIMS

To define the prevalence of dyslipidaemia in young diabetic patients in Peninsular Malaysia and the contributory factors of dyslipidaemia in these subjects.

METHODS

This is a cross-sectional study involving 848 young diabetic patients from seven different centres, with representation from the three main ethnic groups. Clinical history and physical examination was done and blood taken for HbA1c, fasting glucose, total cholesterol, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol and triglycerides.

RESULTS

The overall lipids were suboptimal, worse in Type 2 diabetes mellitus (DM) patients compared with Type 1 DM patients. Of the Type 2 patients, 73.2% had total cholesterol > 5.20 mmol/l, 90.9% had LDL-cholesterol > 2.60 mmol/l, 52.6% had HDL-cholesterol < 1.15 mmol/l and 27.3% had serum triglycerides > 2.30 mmol/l. There were ethnic differences in the lipid levels with the Malays having the highest total cholesterol (mean 6.19 mmol/l), and the highest LDL-cholesterol (mean 4.16 mmol/l), while the Chinese had the highest HDL-cholesterol (geometric mean 1.24 mmol/l). Ethnicity was an important determinant of total, LDL- and HDL-cholesterol in Type 2 DM, and LDL- and HDL-cholesterol and triglycerides in Type 1 DM. Glycaemic control was an important determinant of total, LDL-cholesterol and triglycerides in both Type 1 and Type 2 DM. Waist-hip ratio (WHR) was an important determinant of HDL-cholesterol and triglycerides in both types of DM. Gender was an important determinant of HDL-cholesterol in Type 2 DM, but not in Type 1 DM. Socioeconomic factors and diabetes care facilities did not have any effect on the dyslipidaemia.

CONCLUSIONS

The prevalence of dyslipidaemia was high especially in Type 2 DM patients. Ethnicity, glycaemic control, WHR, and gender were important determinants of dyslipidaemia in young diabetic patients. Diabet. Med. 18, 501-508 (2001)

Leptin and other components of the Metabolic Syndrome in Mauritius--a factor analysis

OBJECTIVE

To use factor analysis to examine the putative role of leptin in the Metabolic Syndrome, and to define better the associations among observed variables and the identified factors.

DESIGN

Factor analysis of cross-sectional data from a 1987 survey.

SUBJECTS

Non-diabetic residents of Mauritius who participated in population-based surveys in 1987 and 1992 (1414 men and 1654 women).

MEASUREMENTS

Fasting and 2 h plasma glucose and insulin following a 75 g oral glucose load; seated blood pressure; body mass index (BMI); waist-to-hip ratio (WHR); and fasting serum triglycerides, HDL-cholesterol, leptin and uric acid concentrations.

RESULTS

Principal components factor analysis revealed three factors for men and women that explained between 54 and 55% of the observed variance of the 12 measured variables. General features of these factors were as follows: factor 1, WHR, BMI, leptin, fasting and 2 h insulin, triglycerides, and HDL-cholesterol; factor 2, systolic and diastolic blood pressure, uric acid (men only), and fasting glucose (women only); and factor 3, fasting and 2 h glucose and insulin. Only three variables loaded on more than one factor with a loading > or = 0.4 (fasting and 2 h insulin, fasting glucose in women only). Leptin loaded on one factor only in both men and women.

CONCLUSIONS

Since multiple factors underlie the Metabolic Syndrome, and since no observed variable loads on all three factors, more than one mechanism might account for the observed clustering of risk characteristics. Leptin does not unite features of this syndrome due to its loading on one factor only. Uric acid is related to a different factor in men and women. The absence of gender differences in factor loadings argues for similar mechanisms for the Metabolic Syndrome in men and women in Mauritius. International Journal of Obesity (2001) 25, 126-131

Epidemiologic study of type 2 diabetes in Taiwan

Diabetes mellitus (DM) in adults is a global health problem, although its prevalence varies widely between different populations and the rate has generally increased worldwide. In Taiwan, the mortality rate from DM has almost doubled over the past 10 years. The prevalence of DM in Taiwan was established between 1985 and 1996 and the rates were between 4.9 and 9.2%. The prevalence of impaired glucose tolerance (IGT) was 15.5% (men 15% and women 15.9%). The prevalence of DM and IGT increased significantly with age for both genders. The significant factors associated with newly diagnosed DM were age, BMI, family history of DM, systolic blood pressure (hypertension), physical activity and serum triglyceride levels. The prevalence of large vessel disease (LVD) in DM and non-diabetic subjects were 20.0 and 12.9%, respectively. Among diabetics, 15.8% had ischemic heart disease (IHD), 1.7% leg vessel disease (leg VD), and 2.5% stroke. In non-diabetics, the prevalence of the aforementioned macroangiopathies were 11.5, 0.2 and 1.2%, respectively. The diabetics had a significantly higher prevalence of macrovascular disease than non-diabetic subjects. The most significantly associated with the LVD was serum cholesterol levels. Serum cholesterol and HbA1(c) were significantly associated with the development of IHD. Cigarette smoking and female gender were significantly associated with the leg VD. The prevalence of diabetic retinopathy (DR) was 35.0%. (background DR 30%, preproliferative DR 2.8% and proliferative DR 2.2%, respectively.) The prevalence of DR for previously and newly diagnosed diabetics were 45.2 and 28.3% (men 42.8 vs. 33.3% and women 47.5 vs. 24.8%), respectively. From multiple logistic regression analysis, duration of DM was the most important risk factor related to DR. Diabetic subjects treated with insulin had a higher risk of developing retinopathy than those treated with dietary control. The prevalence of nephropathy and neuropathy were 12.9 and 23.5%, respectively. For those patients with and those without nephropathy and neuropathy, the duration of DM, percentage of insulin treatment, percentage of hypertension, and fasting plasma glucose were significantly different. Diabetic duration, hypertension, insulin treatment and glycemic control consistently correlated with nephropathy and neuropathy. In conclusion, the prevalence of DM in Taiwan was between 4.9 and 9.2%, and the prevalence of IGT was 15.5%. The possible risk factors of newly diagnosed diabetes were age, family history of DM, BMI, SBP (hypertension), physical activity and triglyceride levels. Diabetes in Chinese subjects share many characteristics similar to other Asian populations. The burden imposed by the chronic complications of diabetes is massive. In Taiwan, the mortality rates from DM have increased greatly over the past 10 years. Reduction of the modificable risk factors such as BMI, hypertenion and dyslipidemia, and increase of physical activity and good glycemic control through public health efforts may help to reduce the risk of DM and its chronic complications.

Relation of generalized and central obesity to cardiovascular risk factors and prevalent coronary heart disease in a sample of American Indians: the Strong Heart Study

OBJECTIVE

To examine the hypothesis linking measures of obesity including body mass index (BMI), waist circumference (waist) and percentage body fat to coronary heart disease (CHD) prevalence and its risk factors in American Indians.

DESIGN

The Strong Heart Study assesses the prevalence of CHD and its risk factors in American Indians in Arizona, Oklahoma and South/North Dakota. Participants underwent a physical examination and an electrocardiogram; anthropometric and blood pressure measurements were taken, as were measurements of glucose, lipoproteins, fibrinogen, insulin, hemoglobin A1c and urinary albumin.

PARTICIPANTS

Data were available for 4549 men and women between 45 and 74 y of age.

MEASUREMENTS

Obesity, measured using body mass index, waist circumference and percentage body fat, was correlated with prevalent CHD and its risk factors.

RESULTS

More than 75% of participants were overweight (BMI>25 kg/m2). Measures of obesity were greater in women than in men, in younger than in older participants, and in participants with diabetes than in nondiabetic participants. CHD risk factors were associated with measures of obesity but, except for insulin concentration, changes in metabolic variables with increasing obesity were small. Associations were not stronger with waist than with BMI. The prevalence of CHD in those whose BMI and/or waist measurements lay in the lowest and highest quintiles, by gender and diabetic status, was similar.

CONCLUSIONS

Although CHD risk factors are associated with obesity in American Indians, distribution of obesity (ie waist) is no more closely related to risk factors than is generalized obesity (ie BMI), and changes in CHD risk factors with obesity were small. Thus, the relations among obesity, body fat distribution and CHD risk may differ in this population.

Body fat distribution in Alaskan Eskimos of the Bering Straits region: the Alaskan Siberia Project

OBJECTIVE

To describe the body fat content and distribution of adult Alaska Natives of the Bering Straits Region.

DESIGN

Cross-sectional screening in the spring of 1994.

SUBJECTS

454 non-pregnant native residents from four rural Alaskan villages.

MEASUREMENTS

Height, weight, waist, hip and thigh circumference, bioelectrical impedance, sagittal abdominal diameter, and triceps, biceps, suprailiac, subscapular and thigh skinfolds.

RESULTS

Mean height, weight and subscapular-to-triceps ratio were higher in men than women. The women had larger waist, hip and thigh circumferences, higher body fatness, as well as larger skinfolds than the men. There were no demonstrable differences between men and women in measures of body fat distribution. The proportions of women and men with high waist-to-hip ratio (>/=0.8 for women, >/=0.9 for men) for low (<25 kg/m2), medium (25-30 kg/m2) and high (>30 kg/m2) body mass index (BMI) groups were compared with a Canadian study of all races. 1 In the lowest BMI subgroup (<25 kg/m2) a much higher proportion of Eskimo women exhibited a high waist-to-hip ratio (91%) than Eskimo men (42%) or Canadian women (29%) or men (51%). In the highest BMI subgroup (>30 kg/m2) Eskimo women were similar in proportion of high waist-to-hip ratio (99%) compared to Eskimo men (100%), but still demonstrated a much greater proportion of subjects with high waist-to-hip ratio than either Canadian men (90%) or women (76%).

CONCLUSIONS

The large abdominal fat depots found in Eskimo women were similar to men, and may indicate that future increases in diabetes mellitus and other metabolic alterations can be anticipated. International Journal of Obesity (2000) 24, 171-179

Sociodemographic determinants of glycaemic control in young diabetic patients in peninsular Malaysia

Recent studies have shown that good glycaemic control can prevent the development of diabetic complications in type 1 and type 2 diabetes. We wished to observe the glycaemic control in patients from different centres in Peninsular Malaysia and the factors that determine it. We recruited 926 patients with diabetes diagnosed before age 40 years from seven different centres, with proportionate representation from the three main ethnic groups. Clinical history and physical examination were done and blood taken for HbA1c and fasting glucose. The overall glycaemic control was poor with geometric mean HbA1c of 8.6% whilst 61.1% of the patients had HbA1c greater than 8%. Glycaemic control in patients with type 2 diabetes varied between various centres and ethnic groups, with the best control obtained in Chinese patients. Significant predictors of HbA1c in both type 1 and type 2 diabetes include access to nurse educators, ethnic background and WHR. In type 2 diabetes, use of insulin was a significant predictor, while in type 1 diabetes, household income was a significant predictor. Socioeconomic status did not have a significant effect in type 2 diabetes. There were no significant differences in the glycaemic control in patients with different educational status. In conclusion, glycaemic control in big hospitals in Malaysia was poor, and was closely related to the availability of diabetes care facilities and ethnic group, rather than socioeconomic status.

Physical activity and incident diabetes mellitus in postmenopausal women

OBJECTIVES

This study determined whether the incidence of diabetes is reduced among physically active older women.

METHODS

We assessed physical activity by mailed questionnaire and 12-year incidence of diabetes (ostensibly type 2 diabetes) in a cohort of 34257 women aged 55 to 69 years.

RESULTS

After adjustment for age, education, smoking, alcohol intake, estrogen use, dietary variables, and family history of diabetes, women who reported any physical activity had a relative risk of diabetes of 0.69 (95% confidence interval = 0.63, 0.77) compared with sedentary women.

CONCLUSIONS

These findings suggest that physical activity is important for type 2 diabetes prevention among older women.

Time to diagnosis and treatment of breast cancer: results from the National Breast and Cervical Cancer Early Detection Program, 1991-1995

OBJECTIVES

This study examined times to diagnosis and treatment for medically underserved women screened for breast cancer.

METHODS

Intervals from first positive screening test to diagnosis to initiation of treatment were determined for 1659 women 40 years and older diagnosed with breast cancer.

RESULTS

Women with abnormal mammograms had shorter diagnostic intervals than women with abnormal clinical breast examinations and normal mammograms. Women with self-reported breast symptoms had shorter diagnostic intervals than asymptomatic women. Diagnostic intervals were less than 60 days in 78% of cases. Treatment intervals were generally 2 weeks or less.

CONCLUSIONS

Most women diagnosed with breast cancer were followed up in a timely manner after screening. Further investigation is needed to identify and then address factors associated with longer diagnostic and treatment intervals to maximize the benefits of early detection.

Modifiable risk factors for Type 2 diabetes mellitus in a peri-urban community in South Africa

AIMS

To investigate the prevalence of Type 2 diabetes mellitus (DM) and its risk factors in a working class peri-urban community in South Africa.

METHODS

A cross-sectional descriptive study was conducted in 1996, where all persons aged 15 years and older, who were resident in randomly selected houses in Mamre, 55 km from the centre of Cape Town, were sampled. Subjects underwent a 75-g oral glucose tolerance test. Socio-demographic and anthropometric data were obtained and physical activity was assessed using a 7-day activity recall questionnaire. The 1985 WHO criteria were used to define diabetes.

RESULTS

The response rate was 64.5% (n = 974). The participants comprised 56% women, 44% men, mean age 37.6 (range 15-86) years. The crude prevalence of Type 2 DM was 7.1% and impaired glucose tolerance (IGT) 8.0%. The age-adjusted prevalence of Type 2 DM was 10.8% (95% confidence interval (CI) 8.2-13.5%) and IGT 10.2% (95% CI 7.7-12.8%). Regression analysis indicated that age (risk ratio (RR) 7.40, 95% CI 3.45-15.86), waist circumference (RR 4.53, 95% CI 2.04-10.05), low total energy expenditure (RR 1.75, 95% CI 1.07-2.56) and family history of diabetes (RR 2.31, 95% CI 1.42-3.77) were independent risk factors for Type 2 DM, while sex, obesity and regular alcohol consumption were not.

CONCLUSIONS

This previously unstudied community has an intermediate prevalence on the international scale of Type 2 DM, which is linked to potentially modifiable risk factors.

Diabetic microangiopathic complications in young Chinese diabetic patients: a clinic-based cross-sectional study

Microangiopathic complications are major causes of morbidity and mortality in diabetic patients. We studied 150 consecutive young Chinese diabetic subjects attending the Prince of Wales Hospital Diabetes Center on their presence of diabetic microangiopathic complications and the relationships with other risk factors. All patients with aged younger than 40 years and had an age of onset of disease at younger than 35 years. Their known duration of diabetes was 57.2 +/- 5.0 months. Of these 150 patients, 50 (33.3%) had microangiopathic complications, 34 (22.7%) had albuminuria, 11 (7. 3%) had peripheral neuropathy, and 21 (14%) had retinopathy. Using multiple logistic regression analysis, albuminuria was independently associated with body-mass index and systolic blood pressure, peripheral neuropathy was associated with fasting plasma glucose and lower high-density lipoprotein cholesterol, and retinopathy was associated with duration of disease and fasting plasma glucose. In conclusion, there were high percentages of microangiopathic complications, particularly albuminuria, in our young Chinese diabetic patients. Obesity, high blood pressure, and poor glycemic control are important for these complications.

Waist to hip ratio, body mass index, and glucose intolerance from Funagata population-based diabetes survey in Japan

To examine the association of body mass index (BMI) and waist-to-hip ratio (WHR) with glucose intolerance among adults age 45 and over, we conducted a population-based study using an oral glucose tolerance test as a primary examination in two areas of Funagata, Japan, in 1990 and 1992. The number of eligible subjects was 1673. The participation rate was 84% (1408/1673). Glucose tolerance was assessed by the 1985 World Health Organization criteria as having diabetes (DM), impaired glucose tolerance (IGT), or normal glucose tolerance (NGT). Analyses by the generalized linear model revealed that both BMI and WHR were higher in the subjects with DM and IGT than those with NGT in both men and women after controlling for age. Analyses employing multiple logistic regression indicated that BMI and WHR were independently associated with IGT and DM in both men and women, except for BMI with IGT for men. The odds ratios for IGT associated with BMI were 1.06 (p=0.19) for men and 1.11 (p<0.01) for women. Those associated with WHR were 2.14 (p<0.01) for men and 1.35 (p<0.01) for women. These results imply that WHR plays an important role for developing DM independent of BMI.

Pakistan National Diabetes Survey: prevalence of glucose intolerance and associated factors in Baluchistan province

The prevalence of diabetes mellitus (DM) and impaired glucose tolerance (IGT) and their relationship to age and obesity was estimated in a population-based survey in urban and rural areas in Baluchistan province, Pakistan. Cluster sampling of 834 adults (260 men, 574 women) in the urban and 570 adults (175 men, 395 women) in the rural areas was carried out. Oral glucose tolerance tests were performed in adults aged 25 years and above. Diagnosis of diabetes and IGT was according to the World Health Organization (WHO) criteria. The overall prevalence of diabetes and IGT in both sexes was 10.8 and 11.9% (urban) versus 6.5 and 11.2% (rural), respectively. The crude prevalence of diabetes in the urban versus rural area was 11.1% in men and 10.6% in women versus 10.3% in men and 4.8% in women. As against this IGT was found in 6.5% of men and 14.3% of women in the urban area and 7.4% of men and 13.0% of women in the rural setting. The major risk factors associated with diabetes were age, positive family history (F/H) of diabetes and obesity. Central obesity was more strongly associated with diabetes in women than men.

The protective effect of good physical fitness when young on the risk of impaired glucose tolerance when old

BACKGROUND

The role of physical activity or fitness on preventing impaired glucose tolerance (IGT) has not been widely investigated. The present case-control study examined the relationship between the occurrence of IGT in men in their 50s and the level of their physical fitness while in their 30s.

METHODS

The subjects consisted of 38 male Japan Self-Defense Forces officials in their 50s who had IGT, as diagnosed by the 75-g oral glucose tolerance test, and 60 control individuals. Nine diabetics were included in the IGT cases. As an indicator of physical fitness between the ages of 30 and 39 years, we selected the best time recorded for each individual during that decade of life for the 1,500-m physical fitness test run. We calculated the odds ratio for IGT in relation to selected risk factors (including physical fitness), and a logistic regression analysis was used to adjust for possible confounding variables.

RESULTS

The odds ratio (95% confidence interval, P value) for IGT with physical fitness in their 30s was 0.25 (0.11-0.58, P < 0.05). With adjustment for a parental history of diabetes and body mass index in both their 30s and their 50s, the odds ratio was 0.31 (0.11-0.86, P < 0.05).

CONCLUSIONS

We concluded that the occurrence of IGT, including diabetes, in men in their 50s can be reduced by maintaining a high level of physical fitness while in their 30s.

A comparison of plasma polymorphonuclear leucocyte elastase levels in obese and lean individuals

Increased release of polymorphonuclear leucocyte (PMNL) elastase, when the PMNLs are activated, can damage tissues in vivo. It was postulated that PMNL elastase might have a tissue-remodelling effect in the body and that obese individuals might have less PMNL elastase activity than lean individuals. To test this hypothesis, plasma PMNL elastase levels were determined in 70 obese individuals and 30 lean normal controls. The PMNL elastase levels (determined by enzyme-linked immunosorbent assay) in the obese group (median 36.2 ng/ml) did not differ significantly from those in the lean healthy controls (32.6 ng/ml; P = 0.5).

Do leptin levels predict weight gain?--A 5-year follow-up study in Mauritius. Mauritius Non-communicable Disease Study Group

OBJECTIVE

To investigate whether relative baseline leptin levels predict long-term changes in adiposity and/or its distribution.

RESEARCH METHODS AND PROCEDURES

In a longitudinal study of 2888 nondiabetic Mauritians aged 25 years to 74 years who participated in population-based surveys in 1987 and 1992, changes in body mass index (BMI), waist/hip ratio (WHR), and waist circumference were compared between "hyperleptinemic," "normoleptinemic," and "hypoleptinemic" groups. "Relative leptin levels" were calculated as standardized residuals from the regression of log10 leptin on baseline BMI to provide a leptin measure independent of BMI. Analyses were performed within each sex. A linear regression model was used to assess the effect of standardized residuals on changes in BMI, WHR, and waist circumference, independent of baseline BMI, age, fasting insulin, and ethnicity.

RESULTS

After adjusting for age and baseline BMI by analysis of covariance, there was no difference in changes in BMI, WHR, or waist circumference between men with low, normal, or high relative leptin levels. Among women, there was a significant difference in deltaWHR across leptin groups, such that the largest increase occurred in the "normal" leptin group. For both men and women, the linear regression models explained approximately 10% of variation in dependent variables, and the only significant independent variables were age, BMI, and being of Chinese origin, compared with Indian origin.

DISCUSSION

These findings do not support a role for leptin concentration in predicting weight gain or changes in fat distribution in adults over a 5-year period.

Obesity and cardiovascular disease

Obesity, diabetes mellitus, and hypertension are common, interrelated medical problems in Westernized, industrialized societies. These interrelated medical conditions are associated with an increased risk of cardiovascular disease and are more prevalent in several minority groups, including African-American and Hispanic populations. The associated cardiovascular risks of these problems are more thoroughly addressed in another review in this supplement. Obesity markedly enhances the development of Type 2 diabetes. Moreover, it enhances the cardiovascular risk associated with other risk factors, such as hypertension and dyslipidemia. Weight reduction in association with an aerobic exercise program improves metabolic abnormalities and reduces blood pressure in individuals with diabetes and hypertension.

Moderate-intensity aerobic training improves glucose tolerance in aging independent of abdominal adiposity

OBJECTIVE

To test the hypothesis that training-related improvements in glucose and insulin responses to an oral glucose tolerance test (OGTT) are independent of changes in abdominal adiposity.

DESIGN

Adiposity and responses to an OGTT were measured before and after a 4-month randomized, controlled aerobic training program.

SETTING

An academic medical institution.

PARTICIPANTS

Sixteen healthy older (73+/-1 year) men and women.

INTERVENTION

Both the training (T) (n=9) and control (C) (n=7) groups exercised 4 times a week for 60-minute sessions. T exercised on mini-trampolines at 55 to 65% of HRmax (determined from a graded treadmill test) for 1 month and then at 75% for 3 months; C engaged in supervised stretching and yoga.

MEASUREMENTS

At baseline and follow-up, we estimated abdominal fat (from computed tomography and anthropometry), plasma glucose, and serum insulin responses to the OGTT and fasting concentrations of free fatty acids (FFA).

RESULTS

Aerobic training resulted in a 16% increase in VO2 peak and a 24% decrease in FFA in the T group (P < .05), but training had no effect on abdominal fat. In the T group, the glucose response curve shifted to the left, and the incremental area under the glucose curve decreased by 25% (P < .05). This improvement in glucose response occurred, however, only in those with impaired glucose tolerance at baseline and without any observed change in insulin response. No change in any variables occurred in the C group.

CONCLUSIONS

Our data suggest that moderate-intensity aerobic training has a favorable effect on glucose tolerance in older people, independent of changes in abdominal adiposity.

Prevention of type 2 diabetes

Type 2 diabetes is a major cause of morbidity and mortality resulting from its microangiopathic and macroangiopathic complications. Current approaches to its management and to the prevention of diabetic complications are difficult to implement effectively, and there is little evidence to date that these approaches are reducing the impact of this disease. The recognition that type 2 diabetes usually has a prolonged prediabetic phase raises the possibility that the emergence of hyperglycemia and the atherosclerotic complications associated with diabetes may be preventable by the institution of early treatment modalities. Sufficient data suggest that life-style modification or pharmacotherapy directed at improving insulin sensitivity or insulin secretion in subjects with impaired glucose tolerance may reduce progression to diabetes. Two long-term prospective, controlled trials have been initiated to test this hypothesis.

The association between dyslipidaemia and obesity in Chinese men after adjustment for insulin resistance

Obesity is associated with dyslipidaemia characterised by increased fasting triglyceride and decreased high-density lipoprotein (HDL) concentrations. Causes for obesity-associated dyslipidaemia include insulin resistance, excessive caloric intake, increased free fatty acid production and disturbances in the counter-regulatory hormones. We examined the relationships between lipid parameters and obesity before and after adjustment of insulin resistance in 902 Hong Kong Chinese men. After adjustment for age, smoking and insulin resistance, increasing body mass index (BMI) and waist-to-hip ratio (WHR) remained closely associated with increased concentrations of triglyceride and apolipoprotein B (apo B), increased ratios between low-density lipoprotein (LDL) and HDL (LDL/HDL), and that between apo B and LDL (apo B/LDL), increased fasting and 2-h plasma glucose and insulin, as well as decreased concentrations of HDL, HDL2 and apolipoprotein A-I (apo A-I). On stepwise multiple regression analysis using age, BMI, WHR, insulin resistance and fasting plasma glucose as independent variables, BMI and WHR were the major determinants for the variance of triglyceride, HDL and its subfractions, LDL/HDL, apo B and apo B/LDL. Age was the most important predictor for total cholesterol and LDL. Insulin resistance only explained less than 1% of the variance in triglyceride and apo B. This was compared to a variance between 10 and 16% in these parameters as explained by BMI and/or WHR. In conclusion, obesity is associated with dyslipidaemia in Chinese men, characterised by increased plasma triglyceride, apo B, LDL/HDL, apo B/LDL, and decreased HDL, HDL2 and apo A-I concentrations. Obesity independent of insulin resistance, in particular central adiposity as reflected by increased WHR, was the most important independent variable for many of these lipid abnormalities. Our results emphasised the multifactorial linkage between obesity and dyslipidaemia.

Specific patterns of food consumption and preparation are associated with diabetes and obesity in a Native Canadian community

We examined the relationship between usual patterns of food intake, fattiness of food preparation and consumption, and diabetes and obesity status in a Native Canadian reserve in northwestern Ontario. Patterns of intake were estimated using a 34-item food frequency instrument. Scales and scores were developed using factor analysis procedures and were tested for reliability using coefficient alpha. Impaired glucose tolerance (IGT) and diabetes status was determined by administering a 75-g glucose tolerance test. A number of the food groups appear to have a protective effect in regard to IGT and diabetes, including vegetables [odds ratio (OR) = 0.41, confidence interval (CI) = 0.18-0.91], breakfast foods (OR = 0.41, CI = 0.18-0. 93) and hot meal foods (OR = 0.29, CI = 0.11-0.78). Most of these foods are relatively high in fiber and low in fat. High consumption of junk foods and the bread and butter group was associated with substantial increases in risk for diabetes (OR = 2.40, CI = 1.13-5. 10; OR = 2.22, CI = 1.22-4.41, respectively). These foods tend to be high in simple sugars, low in fiber and high in fat. More fatty methods of food preparation are also associated with increased risk for diabetes in this population (OR = 2.58, CI = 1.11-6.02). This information has been incorporated into an ongoing community-based diabetes prevention program in the community.

Health risks of immigration: the Yemenite and Ethiopian cases in Israel

Immigration almost always involves major cultural changes in dietary, social and health-related beliefs and behaviour. Two years after the arrival of the earliest Yemenite immigration wave to Israel, about 30 years ago, the prevalence rate of diabetes in that population was almost nonexistent (approximately 0.06%), increasing to approximately 12% 25 years later. Obesity and hyperlipoproteinemia were not always correlated with diabetes. Ethiopians, mainly from the northern regions, first immigrated to Israel ten years ago. At that time, their prevalence rate of diabetes was 0-0.4%. Though it is too early to determine the overall prevalence rate in this population, 5-8% rates have been reported after up to 5 years in Israel. The objective of the present work was to study the effect of the diversity of ethnic food patterns and adaptability on the nutritional status of Ethiopian immigrants. Two groups were studied--teenagers and adults. After 2 and 18 months in Israel, adult Ethiopians who arrived in Israel in 1991 (n = 426) had an average body mass index (BMI) of 20-22 kg/m2, which was below western values; a waist:hip ratio (WHR) of 0.9 suggested abdominal fat accumulation. Fasting serum- glucose levels were within the norm, whereas insulin levels were high (24 micrograms/mL). Plasma triglycerides (TG) increased with age, from about 100 to 150 mg/dL, whereas cholesterol and lipoprotein levels remained stable and normal. The BMI of Ethiopian teenagers (n = 15) 5-7 years in Israel was similar to that found in adults. Fasting serum insulin levels were significantly lower in boys than in girls (approximately 16.6 vs approximately 18.6 microU/mL, respectively). Cholesterol values were significantly higher in girls than in boys (approximately 184 vs approximately 150 mg/dL); TG, high density and low density lipoprotein values were normal. These data indicate the existence of early signs of risk factors for diabetes, which may not manifest itself clinically unless provoked. Several causes, rendered detrimental by progress, could be setting the stage for early manifestation of risk factors for cardiovascular disease and diabetes. Of these, two are of pertinence to this work: a genetic endowment for low-energy output and the thrifty genotype, and maternal undernutrition.

Exercise in the management of non-insulin-dependent diabetes mellitus

The incidence of non-insulin-dependent diabetes mellitus (NIDDM) has increased worldwide during the last decades, despite the development of effective drug therapy and improved clinical diagnoses. NIDDM is one of the major causes of disability and death due to the complications accompanying this disease. For the well-being of the patient, and from a public healthcare perspective, the development of effective intervention strategies is essential in order to reduce the incidence of NIDDM and its resulting complications. For the patient, and for society at large, early intervention programmes are beneficial, especially from a cost-benefit perspective. Physical activity exerts pronounced effects on substrate utilisation and insulin sensitivity, which in turn potentially lowers blood glucose and lipid levels. Exercise training also improves many other physiological and metabolic abnormalities that are associated with NIDDM such as lowering body fat, reducing blood pressure and normalising dyslipoproteinaemia. Clearly, regular physical activity plays an important role in the prevention and treatment of NIDDM. Since physical activity has been shown in prospective studies to protect against the development of NIDDM, physical training programmes suitable for individuals at risk for NIDDM should be incorporated into the medical care system to a greater extent. One general determinant in a strategy to develop a preventive programme for NIDDM is to establish a testing programme which includes VO2max determinations for individuals who are at risk of developing NIDDM. Before initiating regular physical training for people with NIDDM, a complete physical examination aimed at identifying any long term complications of diabetes is recommended. All individuals above the age of 35 years should perform an exercise stress test before engaging in an exercise programme which includes moderate to vigorously intense exercise. The stress test will identify individuals with previously undiagnosed ischaemic heart disease and abnormal blood pressure responses. It is important to diagnose proliferative retinopathy, microalbuminuria, peripheral and/or autonomic neuropathy in patients with NIDDM before they participate in an exercise programme. If any diabetic complications are present, the exercise protocol should be modified accordingly. The exercise programme should consist of moderate intensity aerobic exercise. Resistance training and high intensity exercises should only be performed by individuals without proliferative retinopathy or hypertension. Once enrolled in the exercise programme, the patient must be educated with regard to proper footwear and daily foot inspections. Fluid intake is of great importance when exercising for prolonged periods or in warm and humid environments. With the proper motivation and medical supervision, people with NIDDM can enjoy regular physical exercise as a means of enhancing metabolic control and improving insulin sensitivity.

Relationship between changes in physical activity and plasma insulin during a 2.5-year follow-up study

The association between changes in physical activity, body weight, and diet and fasting plasma insulin was analyzed in a 2.5-year follow-up study of 146 men aged 50 to 60 years. Physical activity was assessed by a 7-day physical activity recall interview, diet by a 4-day food record, and plasma insulin radioimmunologically. Total physical activity decreased from (mean +/- SD) 45.1 +/- 10.1 to 39.0 +/- 6.1 metabolic equivalent (MET) hours (METh).d-1 and conditioning physical activity (> 5.0 METs) from 8.0 +/- 11.2 to 2.7 +/- 5.0 METh.d-1, whereas plasma insulin increased from 8.2 +/- 5.8 to 9.2 +/- 6.7 mU.L-1 and body weight from 80.5 +/- 12.0 to 81.6 +/- 11.6 kg during the follow-up period (P < or = .001 for all). The change in conditioning physical activity correlated inversely (r = -.34, P < .001) and change in body weight positively (r = .42,P < .001) with the change in plasma insulin level. With data adjusted for the baseline insulin level, cardiovascular health status, alcohol intake, change in body weight, smoking, age, and follow-up time, the odds ratio for an increase in fasting plasma insulin was 8.9 (95% CI, 2.1 to 37.1; P = .003) for men with the greatest decrease in conditioning physical activity (< -7 METh) compared with men who reported an increase in conditioning physical activity. The same logistic regression model showed an odds ratio of 9.9 (95% CI, 2.1 to 45.4; P = .003) for the increase in plasma insulin for subjects who gained more than 3.3 kg body weight compared with subjects who lost at least 0.6 kg. Men who consumed at least 12 g.d-1 alcohol at both examinations had an odds ratio of 12.8 (95% CI, 1.7 to 94.5; P = .012) compared with nondrinkers. These data suggest that in middle-aged men, a reduction in physical activity increases the risk for increased plasma insulin independently of alcohol intake and changes in body weight.

Role of exercise training in the prevention and treatment of insulin resistance and non-insulin-dependent diabetes mellitus

Recent epidemiological studies indicate that individuals who maintain a physically active lifestyle are much less likely to develop impaired glucose tolerance and non-insulin-dependent diabetes mellitus (NIDDM). Moreover, it was found that the protective effect of physical activity was strongest for individuals at highest risk of developing NIDDM. Reducing the risk of insulin resistance and NIDDM by regularly performed exercise is also supported by several aging studies. It has been found that older individuals who vigorously train on a regular basis exhibit a greater glucose tolerance and a lower insulin response to a glucose challenge than sedentary individuals of similar age and weight. While the evidence is substantial that aerobic exercise training can reduce the risk of impaired glucose tolerance and NIDDM, the evidence that exercise training is beneficial in the treatment of NIDDM is not particularly strong. Many of the early studies investigating the effects of exercise training on NIDDM could not demonstrate improvements in fasting plasma glucose and insulin levels, or glucose tolerance. The adequacy of the training programmes in many of these studies, however, is questionable. More recent studies using prolonged, vigorous exercise-training protocols have produced more favourable results. There are several important adaptations to exercise training that may be beneficial in the prevention and treatment of insulin resistance, impaired glucose tolerance and NIDDM. An increase in abdominal fat accumulation and loss of muscle mass are highly associated with the development of insulin resistance. Exercise training results in preferential loss of fat from the central regions of the body and should therefore contribute significantly in preventing or alleviating insulin resistance due to its development. Likewise, exercise training can prevent muscle atrophy and stimulate muscle development. Several months of weight training has been found to significantly lower the insulin response to a glucose challenge without affecting glucose tolerance, and to increase the rate of glucose clearance during a euglycaemic clamp. Muscle glucose uptake is equal to the product of the arteriovenous glucose difference and the rate of glucose delivery or muscle blood flow. While it has been known for many years that insulin will accelerate blood glucose extraction by insulin-sensitive peripheral tissues, recent evidence suggests that it can also acutely vasodilate skeletal muscle and increase muscle blood flow in a dose-dependent manner. A reduced ability of insulin to stimulate muscle blood flow is a characteristic of insulin-resistant obese individuals and individuals with NIDDM. Exercise training, however, has been found to help alleviate this problem, and substantially improve the control of insulin over blood glucose. Improvements in insulin resistance and glucose tolerance with exercise training are highly related to an increased skeletal muscle insulin action. This increased insulin action is associated with an increase in the insulin-regulatable glucose transporters, GLUT4, and enzymes responsible for the phosphorylation, storage and oxidation of glucose. Changes in muscle morphology may also be important following training. With exercise training there is an increase in the conversion of fast twitch glycolytic IIb fibres to fast twitch oxidative IIa fibres, as well as an increase in capillary density. IIa fibres have a greater capillary density and are more insulin-sensitive and -responsive than IIb fibres. Evidence has been provided that morphological changes in muscle, particularly the capillary density of the muscle, are associated with changes in fasting insulin levels and glucose tolerance. Furthermore, significant correlations between glucose clearance, muscle capillary density and fibre type have been found in humans during a euglycaemic clamp. Exercise training may also improve control over hepatic glucose production by increasin

The effect of age on cardiovascular risk factors in Chinese women

Chinese women traditionally have a low incidence of coronary heart disease. However, information on cardiovascular risk factors in this population are relatively scarce. We examined these risk factors in 601 Hong Kong Chinese women (age+/-SEM, 38.5+/-0.4 years; range, 18-66 years) stratified into four age groups (group 1, < or =30 years; group 2, 31-40 years; group 3, 41-50 years; group 4, > or =51 years). Increasing age in Chinese women was associated with increased body mass index, waist-to-hip ratio, systolic and diastolic blood pressure, fasting plasma total cholesterol, triglyceride, low-density lipoprotein, apolipoprotein B, fasting and 2-h plasma glucose, glycated haemoglobin, fasting plasma insulin and urate concentrations. After adjustment for body mass index, waist-to-hip ratio and smoking, all these age-related associations remained statistically significant except for fasting plasma insulin concentration. There was a progressive increase with age in the prevalence of glucose intolerance, hypertension, dyslipidaemia and obesity. These prevalence rates further increased in subjects aged 51 years (the mean menopausal age in Asian women) or above. These findings suggest that age had an important and independent effect on cardiovascular risk in Chinese women and that, as in Caucasians, the onset of menopause might further increase this risk.

Design of cost-effective packages of care for non-insulin-dependent diabetes mellitus. Defining the information needs

This review concludes that: a) the global burden of disease from non-insulin-dependent diabetes mellitus (NIDDM) cannot be completely estimated at present; b) evidence for the efficacy of key elements of a package of care is still needed; c) generalizing the results of evaluations of costs or effectiveness across different populations is not straightforward; and d) for this complex intervention, the costs and effectiveness of intervention may be highly dependent on methods of organizing care. Addressing this information deficit represents an important task for researchers and health decision makers.

The global epidemiology of non-insulin-dependent diabetes mellitus and the metabolic syndrome

Non-insulin-dependent diabetes mellitus (NIDDM) constitutes about 85% of all cases of diabetes in developed countries and it has now reached epidemic proportions in many developing nations, as well as disadvantaged groups in developed countries, e.g., Mexican- and African-Americans and Australian Aborigines and Torres Strait Islanders. The diagnosis of NIDDM is usually made after the age of 50 years in Europids, but it is seen at much younger age in these high prevalence populations, which also include Pacific Islanders, Native Americans, and migrant Asian Indians and Chinese. There is enormous variation in NIDDM prevalence between populations, and exceptionally high rates have been documented in populations who have changed from a traditional to a modern lifestyle, e.g., American Pima Indians, Micronesians, and other Pacific Islanders, Australian Aborigines, migrant Asian Indians, and Mexican-Americans. Over the next decade, following the initial phase of the NIDDM epidemic, macro- and microvascular complications will emerge as a major threat to future public health throughout the world with huge economic and social costs. The major cause of death in NIDDM is macrovascular disease (coronary artery, peripheral vascular, and cerebrovascular), which accounts for at least two-thirds of NIDDM mortality. A key strategy in reducing macrovascular disease lies in the better understanding of the Deadly Quartet or Metabolic Syndrome. New data suggest that hyperleptinemia rather than hyperinsulinemia may play an important and central role in the genesis of the cardiovascular disease risk factor cluster that constitutes the Metabolic Syndrome.

Experimental benefit of moxonidine on glucose metabolism and insulin secretion in the fructose-fed rat

OBJECTIVE

Non-insulin-dependent diabetes mellitus (NIDDM) is often associated with hypertension leading to a specifically high cardiovascular risk in these patients. However, there is evidence that insulin resistance and hyperinsulinaemia are not only characteristic for diabetic patients but also for some non-diabetic populations in which a cluster of cardiovascular risk factors is observed (hypertension, hypertriglyceridaemia, obesity). Therefore, hyperinsulinaemia and insulin resistance have been suggested to be of major pathophysiological importance for the development of this syndrome (syndrome X). Since imidazoline receptors are currently considered to be a specific pharmacological target for blood pressure reduction, it is important to know whether and in which way these compounds affect the glucose homoeostasis and insulin release.

DESIGN

The influence of moxonidine on glucose tolerance in vivo was determined in healthy control rats, in rats receiving a high fructose diet for 6 weeks to induce insulin resistance, hyperinsulinaemia and hypertension, and in rats receiving in addition to a high fructose diet moxonidine (1.5 mg/kg body weight daily). In vitro, using isolated pancreatic islets of mice, long-lasting effects (chronic) and immediate (acute) effects of moxonidine on beta-cell function were determined by basal and glucose stimulated insulin release in two different experimental systems: (1) islets were exposed for 24 h (37 degrees C) to various concentrations of moxonidine ranging from 1 nmol/l to 1 mmol/l, followed by a washing procedure to remove excess of moxonidine and then used for the beta-cell function test; (2) islet cultures were incubated again with moxonidine for 24 h (37 degrees C) with either 1 nmol/l or 1 micromol/l. In contrast to the first experiments, however, after the washing procedure moxonidine was added at the same concentration as used for preincubation to test its direct effect on beta-cell function.

RESULTS

In healthy control rats acute administration of moxonidine in vivo impaired the glucose tolerance in high dosages, which effectively reduced the blood pressure (>1 mg/kg body weight). This effect was, however, smaller that that observed by clonidine. In fructose-fed rats, moxonidine completely prevented the development of insulin resistance, hyperinsulinaemia and hypertension. In vitro, pancreatic islets preincubated with moxonidine exhibited dose-dependently both stimulatory and inhibitory chronic effects on beta-cell function compared with that in controls. Preincubation of islet cultures with moxonidine at concentrations between 1 nmol/l and 1 mmol/l resulted in a reduction of basal insulin release which was very pronounced at concentrations higher than 100 nmol/l. The results obtained for glucose-stimulated insulin release opposed in part those for basal insulin release, since the preincubation with moxonidine up to 10 micromol/l gave rise to an increased insulin release. An additional direct effect of moxonidine with a marked reduction of glucose-stimulated insulin release was observed, however, when moxonidine was present during the preincubation (24 h) and the functional test at a concentration of 1 nmol/l or 1 micromol/l.

CONCLUSIONS

Our data suggest that a causal linkage exist between the development of hypertension and insulin resistance/hyperinsulinaemia in the high fructose diet rat model. Since central activation of imidazoline receptors by moxonidine can prevent this syndrome, it follows that an overactivity of the sympathetic nervous system is of major importance. Suppression of this sympathetic overactivity might be an effective approach to reduce hypertension and the concomitant metabolic defect. Therefore, such an interventional strategy could contribute to reduce the cardiovascular risk of NIDDM patients and patients with other forms of insulin resistance/hyperinsulinaemia such as metabolic cardiovascular syndrome.

Waist circumference as the best predictor of noninsulin dependent diabetes mellitus (NIDDM) compared to body mass index, waist/hip ratio and other anthropometric measurements in Mexican Americans--a 7-year prospective study

Although a number of obesity-related variables are recognized risk factors for NIDDM, few studies have addressed which one is the best predictor. A cohort of 721 Mexican Americans aged 25-64 years who were free of NIDDM at baseline were followed for an average of 7.2 years; 105 new cases of NIDDM were diagnosed. Body weight, body mass index (BMI), waist and hip circumferences, waist/hip ratio (WHR), triceps and subscapular skinfolds were all positively predictive of NIDDM independent of age and sex. There were modest to strong correlations between these anthropometric variables, however, waist circumference was the strongest predictor of NIDDM. The predictive power of a single measurement of waist circumference was at least equal to that of WHR and BMI combined. The risk of NIDDM for those in the highest quartile of waist circumference was 11 times greater than for those in the lowest quartile (95% confidence interval: 4.2-28.8). The waist-NIDDM relation was stronger in subjects with BMI < or = 27 kg/m2 (OR: 6.0 for a 1 SD difference) than in subjects with BMI > 27 kg/m2 (OR: 1.7 for a 1 SD difference). In multivariate analysis, waist circumference was the only significant predictor of NIDDM in models that included other anthropometric variables either separately or simultaneously. WHR and BMI were independent predictors of NIDDM after adjustment for each other, however, their predictive abilities disappeared after adjustment for waist circumference. The data indicate that waist is the best obesity-related predictor of NIDDM. This finding suggests that the distribution of body fat, especially abdominal localization, is a more important determinant than the total amount of body fat of the development of NIDDM in Mexican Americans.

Effect of diet and moderate exercise on central obesity and associated disturbances, myocardial infarction and mortality in patients with and without coronary artery disease

OBJECTIVE

To test whether a fat modified and fruit and vegetable enriched diet in conjunction with moderate physical activity reduces the cardiac event rate in patients with coronary artery disease (CAD) and its risk factors in an urban setting in India.

SUBJECTS AND METHODS

480 patients either with CAD or with risk factors. Those with definite or possible CAD including angina pectoris (n = 210) based on World Health Organization criteria and patients with risk factors were assigned to diet A (n = 231) or diet B (n = 232) for a period of 3 years. Both groups were advised to follow a fat modified diet. Group A was also advised to consume at least 400 g/day of fruits, vegetables and legumes according to World Health Organization advice and include moderate physical activity.

RESULTS

Waist-hip ratios, fasting and post-prandial blood glucose, plasma insulin levels, blood pressure and weight fell significantly in patients in group A compared with those in group B. While triglycerides in group A showed a significant decrease, high density lipoprotein cholesterol showed a significant increase. Both groups showed a significant reduction in total and low density lipoprotein cholesterol, although the decrease was greater in group A than group B. Central obesity decreased by 6.2% in group A vs. 1.2% in group B, 95% confidence interval of difference 2.3 to 7.8. The incidence of cardiac events was significantly lower in group A than group B (29 vs. 43 patients, p < 0.01). All-cause mortality also significantly declined in group A compared with group B (16 vs. 24 died, p < 0.05). The group A patients with better adherence to exercise and diet showed greater reduction in central obesity and greater decline in cardiac event rates and total mortality compared to control group B.

CONCLUSIONS

It is possible that moderate physical activity in conjunction with dietary changes in patients with CAD may cause substantial reductions in central obesity and associated disturbances corresponding to a significant decrease in cardiac events and mortality during the follow-up of 3 years.

Nutrition, hormones, and breast cancer: is insulin the missing link?

Breast cancer incidence rates are high in societies with a Western lifestyle characterized by low levels of physical activity, and by an energy-dense diet rich in total and saturated fat and refined carbohydrates. Epidemiologic studies, so far mostly on postmenopausal women, have shown that breast cancer risk is increased in hyperandrogenic women, with decreased levels of plasma sex-hormone binding globulin, and with increased levels of testosterone and of free estrogens. This paper describes the role of hyperinsulinemia as a physiologic link between nutritional lifestyle factors, obesity, and the development of a hyperandrogenic endocrine profile, and reviews evidence that may or may not support the theory that chronic hyperinsulinemia is an underlying cause of breast cancer. An hypothesis is presented, stipulating that breast cancer risk is increased not only in hyperandrogenic postmenopausal women, but also in premenopausal women with mild hyperandrogenism and normal (ovulatory) menstrual cycles. The author suggests further investigation as to whether there is a positive association between risk of breast cancer before menopause and subclinical forms of the polycystic ovary syndrome (PCOS), and to what extent diet and physical activity during childhood, by modulating the degree of insulin resistance during adolescence, may or may not be determinants of a PCO-like hyperandrogenic endocrine profile persisting into adulthood.

Therapeutic challenges in the obese diabetic patient with hypertension

Obesity, diabetes mellitus, and hypertension are common and interrelated medical problems in Westernized, industrialized societies. These medical conditions are associated with an increased risk of cardiovascular disease and are more prevalent among minorities, such as African-American and Hispanic populations. The associated cardiovascular risks of these problems are more thoroughly addressed in another review in this supplement. Obesity markedly enhances the development of type II diabetes. Moreover, it enhances the cardiovascular risk associated with other risk factors, such as hypertension and dyslipidemia. Weight reduction in association with an aerobic exercise program improves metabolic abnormalities and reduces blood pressure in individuals with diabetes and hypertension. Frequently, however, pharmacologic treatment is required to lower blood pressure. Individual therapy with an angiotensin-converting enzyme (ACE) inhibitor is preferred initially in these individuals, with the addition of either a low dose diuretic or a nondihydropyridine calcium antagonist if additional blood pressure reduction is required. These additive agents are recommended, since each has been shown individually to reduce cardiovascular morbidity and to preserve renal function among diabetic patients. Other issues, such as aggressive therapy of lipids and adequate glycemic control, are also important strategies for reducing cardiovascular and renal morbidity and mortality in this very high-risk population.

Exercise in the prevention of atherosclerotic, metabolic and hypertensive diseases: a review

Evidence that physical inactivity and low fitness confer an increased risk of coronary heart disease (CHD) is convincing. There is a graded relationship with the amount of physical activity (or physical fitness), with some evidence that an asymptote is reached in the mid-range. Epidemiological studies have also shown that physically inactive individuals are at greater risk of developing hypertension or non-insulin-dependent diabetes or of experiencing a stroke, but less is known about the nature of these relationships. The effects of exercise on blood pressure, glucose/insulin dynamics and lipoprotein metabolism may contribute to the lower risk of these diseases in people who exercise regularly. Long-term adaptations to regular exercise may result in improved insulin sensitivity and in higher serum concentrations of high-density lipoprotein cholesterol-mediated in part by improved weight regulation. However, the residual effects of individual exercise bouts may, cumulatively, also be important; these "acute' effects may be enhanced when functional capacity is increased through training. More intensive exercise may carry greater benefits in some respects, but it also carries higher risks, for example of orthopaedic injury or triggering of heart attack. Consequently, public health policies should aim to foster a long-lasting commitment to increased levels of frequent, moderate-intensity activity in as many people as possible.

Generalised obesity and regional adiposity in adult white and migrant Muslim males from Pakistan in Peterborough

A comparative study was made of generalised obesity (body mass index; BMI) and the regional distribution of adiposity (measured as circumferences and circumference ratios) in adult White and migrant Muslim males from Pakistan in Peterborough. No significant difference in the prevalence of obesity as measured by the BMI was observed between Whites and Pakistani migrants. Although the mean BMI values were similar in both groups, they had distinctly different body fat patterning. Whites had significantly more upper body, central body and lower body adiposity compared with Pakistani migrants. They also had significantly more total fat as well as upper body:lower body, upper body:central body, and upper body: total fat indices. Within the central body, Whites had significantly more adiposity in the waist region relative to abdomen region (Waist:Abdomen ratio). However, Pakistani migrants had significantly more abdominal adiposity relative to total adiposity (Abdomen:Sum of All Circumferences ratio) than Whites. These preliminary results clearly indicate that there is a tendency for accumulation of adiposity in the abdominal region in Asian men of Pakistani origin compared with White men irrespective of the level of generalised adiposity. The health implications of body fat patterning on non-insulin-dependent diabetes mellitus (NIDDM) and coronary heart disease (CHD) are well-known. The pattern of fat distribution observed in migrant Pakistani males in this study may exist in other migrant groups originating from the Indian sub-continent and could be one of the risk factors predisposing migrant Asians (persons originating from the Indian sub-continent) in Britain to develop NIDDM and CHD irrespective of their generalised (BMI) obesity. Future epidemiological studies should lay more emphasis on morphological fat patterning instead of BMI in Asian migrants in Britain.

Changes in population cholesterol concentrations and other cardiovascular risk factor levels after five years of the non-communicable disease intervention programme in Mauritius. Mauritius Non-communicable Disease Study Group

OBJECTIVE

To study changes in the prevalence of risk factors for cardiovascular disease after a five year population-wide intervention programme promoting a healthy lifestyle in a developing country.

DESIGN

Cross sectional cluster surveys in 1987 and 1992. Methodology included a two hour 75 g oral glucose tolerance test, measurement of body mass index, waist:hip ratio, basal lipid concentrations, and blood pressure; and a lifestyle questionnaire.

SETTING

Mauritius, in the Indian Ocean.

SUBJECTS

All adults aged 25-74 years residing in geographically defined clusters.

MAIN OUTCOME MEASURES

Age standardised prevalence of categorical disease and risk factor conditions and mean levels and frequency distributions of continuous variables.

RESULTS

Response rates were 86.2% (5080/5892) in 1987 and 89.5% (5162/5770) in 1992. Significant decreases were found in the prevalence of hypertension (15.0% to 12.1% in men and 12.4% to 10.9% in women); cigarette smoking (58.2% to 47.2% and 6.9% to 3.7% respectively); and heavy alcohol consumption (38.2% to 14.4% and 2.6% to 0.6% respectively). Moderate leisure physical activity increased from 16.9% to 22.1% in men and from 1.3% to 2.7% in women. Mean population serum total cholesterol concentration fell appreciably from 5.5 mmol/l to 4.7 mmol/l (P < 0.001). The prevalence of overweight or obesity increased, and the rates of glucose intolerance changed little. The population frequency distributions of blood pressure, serum lipid concentration, and a composite risk factor score shifted advantageously.

CONCLUSIONS

Lifestyle intervention projects can be implemented and have positive effects in developing countries. A pronounced improvement in the population lipid profile in Mauritius was probably related to a change in the saturated fat content of a widely used cooking oil.

Prevalence and secular trends in obesity in Pacific and Indian Ocean island populations

Surveys conducted in 10 Pacific island populations and in the multiethnic populations of Mauritius and Rodrigues in the Indian Ocean have provided data on the prevalence of obesity, potential etiological factors and medical hazards associated with obesity. The results indicate that the prevalence of obesity (by body mass index (BMI) in some of these populations is among the highest in the world. Obesity related to degree of modernization is more common in urban than in rural locations and tends to be found more often in women. In two populations where longitudinal data were available, there were dramatic increases in prevalence over relatively short time periods. Obesity contributed to the risk of non-insulin-dependent diabetes mellitus (NIDDM) and was associated with other risk factors for cardiovascular disease (CVD) in all populations, but no relationship could be found with total mortality in three ethnic groups for whom data were available. A genetic susceptibility to obesity combined with social pressures that favor high energy intakes and reduced physical activity are believed to be important in these populations. The challenge for the future lies in developing culturally appropriate programs for preventing obesity and thus reducing associated morbidity, while continuing to research its behavioral and genetic determinants.