Low physical activity and worsening of glucose tolerance: results from a 2-year follow-up of a population sample in Malta

Physical activity, physical fitness, and risk of type 2 diabetes mellitus

Type 2 diabetes mellitus (DM) is a common chronic disease. Cardiovascular disease is the most prevalent complication of DM. In the past decade, the associations of physical activity, physical fitness, and changes in lifestyle with the risk of type 2 DM have been assessed by a number of prospective epidemiologic studies and clinical trials. Several studies also evaluate the joint associations of physical activity, body mass index, and glucose levels with the risk of type 2 DM. The results of 21 prospective studies and four clinical trials demonstrated that moderate or high levels of physical activity or physical fitness, as well as changes in lifestyle (dietary modification and enhanced physical activity) could prevent type 2 DM.

Glucose control and walking in a multiethnic sample of older adults

BACKGROUND

Although walking is the most commonly reported physical activity by older adults, there is a paucity of data determining the relationship between objectively determined walking behavior and glucose dynamics in older adults.

OBJECTIVE

This study was designed to investigate the relationship between objectively determined walking behavior and glucose control in a multiethnic sample of older adults.

METHODS

Data were collected on 142 older adults (age 72.1 +/- 9.2 years; body mass index (BMI) 29.4 +/- 6.3; 37 males, 105 females). Anthropometric measures, fasting plasma glucose (FG), and glycosylated hemoglobin A(1c) (HbA(1c)) were assessed; race/ethnicity was self-reported. The study participants wore a pedometer for 7 consecutive days.

RESULTS

The average number of steps/day reported by the entire group was 3,939 +/- 232. White participants (n = 48) were older (p = 0.019), taller (p = 0.002), had lower waist circumference (WC) (p = 0.021), HbA(1c) (p = 0.001) and FG (p = 0.007), and did not differ in average steps/day (p = 0.162) or BMI (p = 0.280) as compared with nonwhite participants (n = 94). Individuals with HbA(1c) values <7% and those with FG <100 mg/dl walked about 1,343 more steps/day than those with unfavorable HbA(1c) and/or FG values. Age, race/ethnicity, WC, BMI, log base 10 of steps/days, and type 1 and 2 diabetes medications accounted for 37.5% of the variance in inverse HbA(1c) (p < 0.001), with significant or near significant individual model contributions consisting of WC (beta = -0.316, B = -0.001, SE = 0.000, p = 0.047), BMI (beta = 0.310, B = 0.001, SE = 0.001, p = 0.050), diabetic medication (beta = -0.473, B = -0.035, SE = 0.006, p < 0.001), and log base 10 of steps/day (beta = 0.198, B = 0.019, SE = 0.010, p = 0.056). Interpretations of transformed data illustrate that greater WC and being on diabetic medications are associated with higher HbA(1c) levels. Further, there is a trend to suggest that fewer accumulated steps/day and lower BMI are associated with higher HbA(1c) concentrations.

CONCLUSIONS

This study demonstrated that objectively determined walking behavior and indicators of obesity were modest predictors of chronic glucose control, after accounting for glucose-altering medications, in this multicultural sample of older adults. Further, when comparing individuals with good glucose control to those with less favorable glucose control, walking an additional 0.5-0.75 miles was associated with better glucose control.

Epidemiological studies of exercise in diabetes prevention

Type 2 diabetes is one of the fastest growing public health problems in both developed and developing countries. It is estimated that the number of people with diabetes in the world will double in coming years, from 171 million in 2000 to 366 million in 2030. Cardiovascular disease accounts for more than 70% of total mortality among patients with type 2 diabetes. The associations of physical activity, physical fitness, and changes in the lifestyle with the risk of type 2 diabetes have been assessed by a number of prospective studies and clinical trials in the past decade. Several studies have also evaluated the joint associations of physical activity, body mass index, and glucose levels with the risk of type 2 diabetes. Prospective studies and clinical trials have shown that moderate or high levels of physical activity or physical fitness and changes in the lifestyle (dietary modification and increase in physical activity) can prevent type 2 diabetes. Our review of the scientific evidence confirms that 30 min/d of moderate- or high-level physical activity is an effective and safe way to prevent type 2 diabetes in all populations.

Lifestyle intervention for the prevention of type 2 diabetes mellitus: putting theory to practice

Type 2 diabetes mellitus is a serious, growing, and costly public health problem. The disease is chronic and degenerative, and thus primary prevention is desirable. Observational studies have linked type 2 diabetes to specific lifestyle behaviors. Several recent major clinical trials confirm that type 2 diabetes can be delayed or prevented in people at high risk; multicomponent lifestyle modification can reduce the incidence of diabetes up to 58%. The American Diabetes Association has recently recommended that lifestyle interventions to prevent or delay diabetes be delivered to people with prediabetes. Delivery of lifestyle interventions in practice is fraught with challenges, but there are several tools and practical strategies available for the implementation of trial findings.

Combined hormone therapy in postmenopausal women with features of metabolic syndrome. Results from a population-based study of Swedish women: Women’s Health in the Lund Area study

OBJECTIVE

To delineate the influence of hormone therapy (HT) on features of metabolic syndrome with special reference to the composition and mode of administration of three specific HT regimens, all containing estradiol (E2) + norethisterone.

DESIGN

The Women's Health in the Lund Area project screened all women (n = 10,766), born between 1935 and 1945. Complete data were obtained from 6,917 women. Those at or above defined cutoff limits were considered positively screened (n = 3,593) for metabolic syndrome. All of them were invited to undergo an oral glucose tolerance test; 2,923 women accepted. After excluding 200 women with impaired fasting glucose, 2,723 women were included in the present analysis. Serum lipids were determined by conventional standard methods at the department of clinical chemistry of Lund University Hospital.

RESULTS

According to World Health Organization criteria, 2,123 women had normal glucose tolerance and 600 women had impaired glucose tolerance (IGT). IGT was less common (P = 0.001) among users of a transdermal patch [CYC-TRANS; E2 50 microg + norethisterone acetate (NETA) 250microg] compared with the two-combined oral regimen [CON-O (continuous oral E2 2 mg + NETA 1 mg) + CYC-O (sequential oral E2 2 mg + NETA 1 mg)]. Furthermore, IGT was more common among CON-O users when compared with either the CYC-O + CYC-TRANS group (P = 0.002) or the CYC-TRANS only group (P = 0.001). There were no significant differences between CYC-O versus CYC-TRANS or CON-O. Serum levels of total cholesterol were higher in the CYC-TRANS group than in the combined CON-O + CYC-O group (P < 0.05); they also were higher (P = 0.05) when comparing the CYC-O + CYC-TRANS versus CON-O as well as higher in CYC-TRANS versus CON-O (P < 0.05). Serum high-density lipoprotein cholesterol levels were higher in the CYC-O (P = 0.001), CYC-TRANS (P < 0.05), and the CYC-O + CYC-TRANS (P = 0.001) groups when compared with the CON-O users. There were no differences in the mean age, blood pressure (systolic and diastolic), body mass index, waste-hip ratio, or the rate of cigarette and alcohol consumption between the different hormone regimens.

CONCLUSION

The risk of having a pathological glucose load was lower in transdermal versus oral users of HT. Transdermal HT could be regarded as first-line treatment in women at risk of developing diabetes.

Age, body mass index and Type 2 diabetes-associations modified by ethnicity

AIMS/HYPOTHESIS

The aim of this study was to assess the effect of ethnicity on the association between age and body mass index as well as the prevalence of diabetes.

METHODS

We selected population-based studies carried out after 1980 in the DECODE/A studies representing different ethnic groups: 11 European, 1 Maltese, 3 Indian, 2 Chinese and 3 Japanese surveys. The total numbers of subjects were 14,240 men and 15,129 women who were 30 to 89 years of age. Diabetes was diagnosed according to the 1999 World Health Organization criteria based on a standard 75 g OGTT. Sex-specific prevalence of diabetes by age and BMI was stratified by ethnic group, in particular the interaction of ethnicity on the associations between age/BMI and the prevalence of diabetes.

RESULTS

The prevalence of diabetes was higher in studies from India and Malta compared to Japan, China, and the rest of Europe. The association between BMI and diabetes, adjusted for age, showed noticeable differences between the ethnic groups with an increase in prevalence starting at a BMI between 15 and 20 kg/m(2) in the Maltese and Indian populations compared to 25 kg/m(2 )in Europeans.

CONCLUSION/INTERPRETATION

The effect of BMI on the age-adjusted prevalence of Type 2 diabetes was modified by ethnicity with considerably lower thresholds in Indian and Maltese subjects compared to those from the rest of Europe. This difference should be reflected in national and international recommendations regarding "optimal" BMI.

Occupational, commuting, and leisure-time physical activity in relation to risk for Type 2 diabetes in middle-aged Finnish men and women

AIM/HYPOTHESIS

Leisure-time physical activity can reduce the risk of Type 2 diabetes, but the potential effect of different types of physical activity is still uncertain. This study is to examine the relationship of occupational, commuting and leisure-time physical activity with the incidence of Type 2 diabetes.

METHODS

We prospectively followed 6898 Finnish men and 7392 women of 35 to 64 years of age without a history of stroke, coronary heart disease, or diabetes at baseline. Hazards ratios of incidence of Type 2 diabetes were estimated by levels of occupational, commuting, and leisure-time physical activity.

RESULTS

During a mean follow-up of 12 years, there were 373 incident cases of Type 2 diabetes. In both men and women combined, the hazards ratios of diabetes associated with light, moderate and active work were 1.00, 0.70 and 0.74 (p=0.020 for trend) after adjustment for confounding factors (age, study year, sex, systolic blood pressure, smoking, education, the two other types of physical activity and BMI). The multivariate-adjusted hazards ratios of diabetes with none, 1 to 29, and more than 30 min of walking or cycling to and from work were 1.00, 0.96, and 0.64 (p=0.048 for trend). The multivariate-adjusted hazards ratios of diabetes for low, moderate, high levels of leisure-time physical activity were 1.00, 0.67, and 0.61 (p=0.001 for trend); after additional adjustment for BMI, the hazards ratio was no longer significant.

CONCLUSIONS/INTERPRETATION

Moderate and high occupational, commuting or leisure-time physical activity independently and significantly reduces risk of Type 2 diabetes among the middle-aged general population.

Sedentary lifestyle and risk of obesity and type 2 diabetes

Obesity and type 2 diabetes have reached epidemic proportions in the United States. It is well-established that increasing physical activity plays an important role in reducing risk of obesity and diabetes. Few studies, however, have examined the association between sedentary behaviors such as prolonged television (TV) watching and obesity and diabetes. Using data from a large prospective cohort study, the Health Professionals' Follow-up Study, we have demonstrated that increasing TV watching is strongly associated with obesity and weight gain, independent of diet and exercise. Also, prolonged TV watching is associated with a significantly increased risk of type 2 diabetes. Men who watched TV more than 40 h per week had a nearly threefold increase in the risk of type 2 diabetes compared with those who spent less than 1 h per week watching TV. The increased risk was not entirely explained by the decreased physical activity and unhealthy eating patterns associated with TV watching. Thus, public health campaigns to reduce the risk of obesity and type 2 diabetes should promote not only increasing exercise levels but also decreasing sedentary behaviors, especially prolonged TV watching.

Age- and sex-specific prevalences of diabetes and impaired glucose regulation in 13 European cohorts

OBJECTIVE

To report the age- and sex-specific prevalences of diabetes and impaired glucose regulation (IGR) according to the revised 1999 World Health Organization criteria for diabetes in Europe.

RESEARCH DESIGN AND METHODS

A total of 13 studies from nine European countries with 7,680 men and 9,251 women aged 30-89 years were included in the data analysis.

RESULTS

In most of the study populations, the age-specific prevalences of diabetes were <10% in subjects younger than 60 years and between 10 and 20% at 60-79 years of age. Mean 2-h plasma glucose (2hPG) concentration increased linearly with age, but fasting plasma glucose (FPG) concentration did not. The increase in the prevalence of undiagnosed diabetes and IGR in the elderly was mainly a result of the large increase in 2hPG rather than FPG. Diabetes and impaired fasting glycemia defined by isolated fasting hyperglycemia was more common in men than in women 30-69 years of age, whereas the prevalence of isolated postload hyperglycemia, particularly impaired glucose tolerance, was higher in women than in men, especially in the elderly (individuals >70 years of age). More than half of the diabetes was undiagnosed in subjects younger than 50 years of age.

CONCLUSIONS

Most European populations have a moderate to low prevalence of diabetes and IGR. Diabetes and IGR will be underestimated in Europe, particularly in women and in elderly men, if diagnoses are based on fasting glucose determination alone.

A screening procedure detecting high-yield candidates for OGTT. The Women's Health in the Lund Area (WHILA) study: a population based study of middle-aged Swedish women

The objective was to evaluate a screening procedure for detecting high-yield candidates for an OGTT, in a population of middle-aged Swedish women. A two-step screening procedure was performed in 6917 subjects. Women with a positive screening outcome, i.e. increased non-fasting capillary blood glucose, serum triglycerides, BMI, WHR, blood pressure or a family history of diabetes, pharmacological treatment of hypertension or hyperlipidaemia at the primary screening underwent a 75-g OGTT. A control group of women with negative screening outcome (n = 221) also underwent an OGTT. In 2923 women with positive screening outcome, 517 (17.7%) had NFG/IGT (normal fasting venous blood glucose <5.6 mmol/l and 2h-glucose 6.7-9.9 mmol/l), 109 (3.7%) IFG/IGT (fasting 5.6-6.0 and 2h 6.7-9.9 mmol/l) and 223 (7.6%) diabetes (fasting > or = 6.1 or 2h > or = 10.0 mmol/l). These figures were three, five and four times higher, respectively, than in the control group with negative screening outcome (p < 0.001 for all); no differences were found for IFG/NGT (fasting 5.6-6.0 and normal 2h < 6.7 mmol/l) (4.6% vs. 7.2%). For predicting impaired glucose metabolism (IFG/NGT, NFG/IGT, IFG/IGT, diabetes), the screening instrument showed an estimated sensitivity of 70%, specificity of 55%, positive predictive value of 34% and negative predictive value of 85%, based on findings in the control sample. The odds ratio for NFG/IGT increased with the numbers of risk factors from 2.8 to 7.7, for IFG/ IGT from 5.7 to 55.0 and for diabetes from 2.5 to 18.1. High B-glucose, WHR and BMI were the three most important factors associated with an increased risk for NFG/IGT, IFG/IGT and diabetes. In subjects with IFG/NGT, none of the screening variables was associated with an increased risk. In summary, the results show a population screening method focused on features of the metabolic syndrome that discloses high-yield candidates for OGTT. A high prevalence of unknown impaired glucose metabolism was found in middle-aged women with a positive screening profile.

Age, body mass index and glucose tolerance in 11 European population-based surveys

AIMS

To describe the variation in the estimated prevalence of diabetes and impaired glucose regulation (IGR) within Europe in relation to age and body mass index (BMI).

METHODS

Cross-sectional data from European population-based studies with both fasting and 2-h glucose after a standard 75-g oral glucose tolerance test were included (9449 men, 7752 women).

RESULTS

There was a large variation in the estimated prevalence of diabetes and impaired glucose regulation among 11 European centres, ranging from 2% to 24% for diabetes and 5% to 43% for IGR. In cross-sectional analysis the estimated prevalence of diabetes and IGR increased with age and BMI. The impact of age did not differ between centres with similar age range, and the impact of BMI was similar in most centres.

CONCLUSIONS

Differences in age and BMI within Europe partly explained the variation in estimates of the IGR and diabetes prevalence. The impact of age and BMI did not differ between centres. Variations in prevalence must therefore be due to other factors that we could not adjust for, such as methodology, differences in diet, physical activity and genetic predisposition.

American College of Sports Medicine position stand. Exercise and type 2 diabetes

Physical activity, including appropriate endurance and resistance training, is a major therapeutic modality for type 2 diabetes. Unfortunately, too often physical activity is an underutilized therapy. Favorable changes in glucose tolerance and insulin sensitivity usually deteriorate within 72 h of the last exercise session: consequently, regular physical activity is imperative to sustain glucose-lowering effects and improved insulin sensitivity. Individuals with type 2 diabetes should strive to achieve a minimum cumulative total of 1,000 kcal x wk(-1) from physical activities. Those with type 2 diabetes generally have a lower level of fitness (VO2max) than nondiabetic individuals. and therefore exercise intensity should be at a comfortable level (RPE 10-12) in the initial periods of training and should progress cautiously as tolerance for activity improves. Resistance training has the potential to improve muscle strength and endurance, enhance flexibility and body composition, decrease risk factors for cardiovascular disease, and result in improved glucose tolerance and insulin sensitivity. Modifications to exercise type and/or intensity may be necessary for those who have complications of diabetes. Individuals with type 2 diabetes may develop autonomic neuropathy, which affects the heart rate response to exercise, and as a result, ratings of perceived exertion rather than heart rate may need to be used for moderating intensity of physical activity. Although walking may be the most convenient low-impact mode, some persons, because of peripheral neuropathy and/or foot problems, may need to do non-weight-bearing activities. Outcome expectations may contribute significantly to motivation to begin and maintain an exercise program. Interventions designed to encourage adoption of an exercise regimen must be responsive to the individual's current stage of readiness and focus efforts on moving the individual through the various "stages of change."

Reduction in body weight helps to delay the onset of diabetes even in non-obese with strong family history of the disease

Of the 1200 non-diabetic offspring of non-insulin-dependent diabetic patients registered under the prevention programme, 262 (M:F 189:73) were available for analysis with greater than or equal to 4 years of follow-up. All of them had been prescribed a calorie restricted diet to suit their body weight, occupation and age, and were advised to restrict the use of refined carbohydrates and fats. Regular exercise was also advised. Compliance with these prescriptions was assessed at each follow up. At the time of analysis, it was noted that only 14.5% had developed diabetes in a period of 8 +/- 4.2 years even though many of them had impaired glucose tolerance at entry in the programme. Multiple regression analysis showed that initial 2 h plasma glucose, initial glucose tolerance and gain in body weight were strong predictors of diabetes. Weight loss occurred in persons who adhered to diet and exercise programmes and conversion to diabetes was lower in them compared to those who gained weight (P < 0.002). Although the rate and degree of obesity is less among Indians, it has been observed in several earlier studies that even a minor increase in body mass index increased the risk of diabetes. This study highlights the fact that measures to control weight helps to delay the onset of diabetes even in the non-obese despite a strong family history of the disorder.

Physical activity epidemiology as applied to elderly populations

Physical activity epidemiological studies provide one of many types of research evidence that are necessary to assess the importance of physical activity to health. Available epidemiological evidence, when coupled with relevant experimental and clinical research, suggests that physical activity has the potential to favourably influence the development and progression of a variety of chronic diseases and conditions that are a burden to public health. The evidence is only beginning to emerge for elderly populations, however, thereby highlighting an important void in our scientific knowledge. Attempting to increase the level of physical activity of elderly people raises three important issues. First, improving adherence to a physically active life-style requires assistance of behavioural scientists, either through direct intervention, or through research that can help the elderly identify and overcome impediments to physical activity. Second, many elderly people have diseases that can limit their physical ability, but exercise scientists can assist by prescribing exercise that is both efficacious and safe given the level of limitation. Third, the number of injuries may increase with increased physical activity in elderly persons. Epidemiologists and exercise scientists working in the area of injury control can determine which activities are safe at specific levels of physical ability and function. To quote one of the originators of exercise physiology, Per Olaf Astrand (1992), 'As a consequence of diminished exercise tolerance, a large and increasing number of elderly people will be living below, at, or just above "thresholds" of physical ability, needing only a minor intercurrent illness to render them completely dependent'. Physical activity can help to push back that 'threshold of physical ability' and thereby improve physical functioning. As physical function improves, there is a propensity to perform even greater amounts of physical activity that may be essential to the quality and perhaps quantity of life for an elderly person.

Gestational diabetes: a challenge for the future

It is well established that pregnancy is associated with temporary changes in maternal metabolism which include a decrease in maternal insulin sensitivity to values similar to those associated with Type 2 diabetes. Fasting glucose concentrations fall throughout pregnancy, postprandial values rise. The maintenance of glucose tolerance in pregnancy requires a two- to three-fold increase in postprandial maternal insulin secretion. Glucose intolerance develops in women unable to compensate for the metabolic changes incurred by pregnancy. Increasing maternal hyperglycaemia is associated with increasing pregnancy morbidity and an increased likelihood of subsequent diabetes in the mother. In addition, maternal hyperglycaemia has a direct effect on the development of the fetal pancreas and is associated with an increased susceptibility to future diabetes in the infant, an effect which is independent of genetic factors. Gestational diabetes mellitus (GDM) is defined as glucose intolerance first recognized in pregnancy, and by definition includes a small number of women with previously unrecognized diabetes or impaired glucose tolerance (IGT). Figures on the prevalence of GDM vary between maternity units, depending on screening methods and the ethnic distribution of the populations. However, in a comprehensive study of a multi-ethnic antenatal population in inner London, UK it was found that only 2% of pregnant women develop significant glucose intolerance. Obstetricians and physicians debate the importance of identifying this 2% of women. The lack of agreed criteria for diagnosing gestational diabetes and the questionable obstetric benefits of treating all women with mild disturbances of glucose tolerance in pregnancy has resulted in few UK centres undertaking universal screening for GDM.(ABSTRACT TRUNCATED AT 250 WORDS)