Clustering of protective factors for glucose intolerance and insulin resistance: a cross-sectional study

The relationship between pre-pregnancy dietary patterns adherence and risk of gestational diabetes mellitus in Iran: A case-control study

AIM

The present study aimed to investigate major dietary patterns and their association with risk of gestational diabetes mellitus (GDM) in Yazd city located in Iran.

METHODS

This case-control designed study was conducted at six healthcare centres. Two hundred and seventy-eight pregnant women who referred for GDM screening participated. Dietary assessment was carried out by using a 67-item validated food frequency questionnaire to evaluate dietary history of participants during the last year. Principal component analysis was used to identify major food patterns. Multivariable logistic regression model was employed to identify the association between dietary patterns and risk of GDM.

RESULTS

Two major dietary patterns were detected. The Western dietary pattern was associated with higher intakes of sugar-sweetened beverages, refined grain products, fast foods, salty snacks, sweets and biscuit, mayonnaise and saturated oils, while the prudent dietary pattern was associated with higher intakes of fruits, low-fat dairy, potato, egg, fish, poultry, nuts, organs meat and red meat. Furthermore, prudent dietary pattern was negatively associated with GDM risk (OR = 0.88, 95% CI: 0.44-0.99). However, there was no significant association between adherence of the Western dietary pattern and risk of GDM.

CONCLUSIONS

Pre-pregnancy adherence of the prudent dietary pattern was significantly associated with reduced risk of GDM.

The cumulative effect of core lifestyle behaviours on the prevalence of hypertension and dyslipidemia

BACKGROUND

Most cardiovascular disease (CVD) occurs in the presence of traditional risk factors, including hypertension and dyslipidemia, and these in turn are influenced by behavioural factors such as diet and lifestyle. Previous research has identified a group at low risk of CVD based on a cluster of inter-related factors: body mass index (BMI) < 25 Kg/m2, moderate exercise, alcohol intake, non-smoking and a favourable dietary pattern. The objective of this study was to determine whether these factors are associated with a reduced prevalence of hypertension and dyslipidemia in an Irish adult population.

METHODS

The study was a cross-sectional survey of 1018 men and women sampled from 17 general practices. Participants completed health, lifestyle and food frequency questionnaires and provided fasting blood samples for analysis of glucose and insulin. We defined a low risk group based on the following protective factors: BMI <25 kg/m2; waist-hip ratio (WHR) <0.85 for women and <0.90 for men; never smoking status; participants with medium to high levels of physical activity; light alcohol consumption (3.5-7 units of alcohol/week) and a "prudent" diet. Dietary patterns were assessed by cluster analysis.

RESULTS

We found strong significant inverse associations between the number of protective factors and systolic blood pressure, diastolic blood pressure and dyslipidemia. The prevalence odds ratio of hypertension in persons with 1, 2, 3, > or = 4 protective factors relative to those with none, were 1.0, 0.76, 0.68 and 0.34 (trend p < 0.01). The prevalence odds ratio of dyslipidemia in persons with 1, 2, 3, > or = 4 protective factors relative to those with none were 0.83, 0.98, 0.49 and 0.24 (trend p = 0.001).

CONCLUSION

Our findings of a strong inverse association between low risk behaviours and two of the traditional risk factors for CVD highlight the importance of 'the causes of the causes' and the potential for behaviour modification in CVD prevention at a population level.

Sex may modify the effects of macronutrient intake on metabolic syndrome and insulin resistance in American Indians: the strong heart study

BACKGROUND

Diet has been related to several characteristics of metabolic syndrome (MSDR) and insulin resistance, which carry an increased risk for diabetes and heart disease.

OBJECTIVE

To examine the cross-sectional association between macronutrient intake, sex, and MSDR and insulin resistance in American Indians without diabetes.

DESIGN

Dietary intake, MSDR, and insulin resistance (estimated by homeostasis model assessment) were assessed.

SUBJECTS/SETTING

Data were analyzed from participants with complete dietary data (n=1,516 for MSDR, n=1,458 for insulin resistance) from the second examination (1993-1995) of the Strong Heart Study, a longitudinal, population-based study of cardiovascular disease and its risk factors in American Indians.

STATISTICAL ANALYSES

Logistic regression and analysis of covariance were used to study associations among tertiles of macronutrient intake and MSDR and homeostasis model assessment scores.

RESULTS

Polyunsaturated fatty acid intake was associated with less MSDR and lower homeostasis model assessment scores in women (odds ratio 0.69 and 95% confidence interval 0.50 to 0.96 for MSDR in the third tertile) but not men. Higher simple carbohydrate intake was associated with more MSDR in men (odds ratio 1.72 and 95% confidence interval 1.10 to 2.69 in the third tertile) but not women.

CONCLUSIONS

Polyunsaturated fatty acid and simple carbohydrates may be associated with MSDR and insulin resistance in American Indians and sex may modify the association between dietary intake and MS and insulin resistance in this population. Further studies should focus on the longitudinal association between dietary intake and incidence of MSDR and insulin resistance and the role of sex in this relationship in American Indians and other populations.

Insulin resistance and sympathetic overactivity in women

Insulin sensitivity decreases for the first time in females at the time of menarche. A much more profound decrease in insulin sensitivity is observed at the end of pregnancy. This physiological insulin resistance is not accompanied by a rise in overall sympathetic activity as reflected in plasma noradrenaline levels, but there is evidence of moderate sympathetic overactivity in muscle and the heart. Pre-eclampsia is characterized by increased insulin resistance, sympathetic overactivity and a particular lipid profile. Thus it is the first manifestation of metabolic syndrome. Women with a history of pre-eclampsia have persistent insulin resistance after pregnancy associated with increased sympathetic activity of the cardiovascular system, and coronary artery disease later in life. Aging is accompanied by a greater increase in sympathetic traffic in women than in men, and inflammation (measured via C-reactive protein) seems to be more strongly related to metabolic syndrome in women than in men. The clinical relevance of these observations remains to be shown. As the key factors of metabolic syndrome, such as insulin resistance and sympathetic overactivity, are closely inter-related, treatment should be aimed at cutting the vicious circle at many points: lifestyle modification (diet, increasing exercise) as a basis of therapy, use of insulin sensitizers (e.g. metformin) to decrease insulin resistance, central sympatholytics (e.g. moxonidine), and AT-receptor blockers or angiotensin-converting enzyme (ACE) inhibitors to overcome sympathetic overactivity, hypertension and inflammation.