Low carbohydrate does not mean low glycaemic index!

Overall glycaemic index and glycaemic load of habitual diet and risk of heart disease

OBJECTIVE

To test the hypothesis that diets with high glycaemic index (GI) and glycaemic load (GL) increase the risk of heart disease.

DESIGN

Overall GI and GL were assessed from 7 d diet records or diet history interviews.

SETTING

Information on hospitalization and death due to CVD and CHD was obtained from the National Register of Cause of Death and the National Register of Patients.

SUBJECTS

In total 3959 adult Danes were - depending on time of entry - followed for 6-25 years until 31 December 1999.

RESULTS

Overall GI was inversely associated with heart disease in men. The hazard ratios (95 % CI) for the 10th and 90th GI percentiles compared with the median were 1.38 (1.13, 1.68) and 0.90 (0.76, 1.07) for CVD morbidity, 1.45 (1.05, 1.99) and 0.81 (0.62, 1.06) for CVD mortality, and 1.31 (0.97, 1.76) and 0.65 (0.51, 0.84) for CHD morbidity. In male subjects GL was not associated with either outcome. In women no clear association between overall GI and heart disease was found, whereas positive non-linear associations were found for GL: at very high levels of GL, increase in GL was associated with increasing CVD and CHD morbidity.

CONCLUSIONS

In men low-GI diets were associated increased risk of heart disease and GL was not associated with heart disease. In women there was no clear association between GI and heart disease, but to some extent a positive association between GL and heart disease was observed as hypothesized.

Glycaemic index and glycaemic load in relation to blood lipids – 6 years of follow-up in adult Danish men and women

Background

Cross-sectional studies have suggested an association between glycaemic index (GI) or glycaemic load (GL) and serum lipids. However, no prospective studies have been performed.

Objective

To examine whether GI or GL was associated with subsequent changes in serum lipids.

Design

Prospective study with 6 years of follow-up. Overall dietary GI and GL of each participant were assessed from diet history interviews.

Setting

Population-based study.

Subjects

Three hundred and thirty-five healthy men and women aged 35–65 years selected randomly from a larger sample of Danish adults.

Results

In men GI was directly related to changes in total cholesterol (ΔTC), regression coefficient (β) = 0.0044 (95% confidence interval (CI): 0.0008–0.0081) and GL was positively related to changes in low-density lipoprotein cholesterol (ΔLDL),β= 0.1554 (95% CI: 0.0127–0.2982). Furthermore, the relationship between GL and ΔTC was modified by age, being particularly strong for the younger men (P= 0.02). In women the relationship between GI and ΔLDL was modified by age and was stronger for younger rather than older women (P= 0.01). A tendency for a similar interaction was seen for GI and ΔTC (P= 0.09). Associations between GL and ΔLDL and GL and ΔTC were inverse for women with body mass index ≥ 30 kg m−2(P= 0.03 and 0.04, respectively).

Conclusions

This is the first study to demonstrate that dietary GI and GL are related to 6-year changes in serum lipid levels. However, associations were weak and generally confined to subgroups.

Glycemic index and glycemic load in relation to changes in body weight, body fat distribution, and body composition in adult Danes

BACKGROUND

A diet with a high glycemic index (GI) and glycemic load (GL) may promote overconsumption of energy and increase the risk of weight gain.

OBJECTIVE

The objective of the study was to investigate the relation between GI and GL of habitual diets and subsequent 6-y changes in body weight, body fat distribution, and body composition in a random group of adult Danes.

DESIGN

A prospective cohort study was conducted in a subsample of men and women from the Danish arm of the Monitoring Trends and Determinants in Cardiovascular Disease study. The subsample comprised 185 men and 191 women born in 1922, 1932, 1942, or 1952. A baseline health examination and a dietary history interview were carried out in 1987 and 1988; a follow-up health examination was performed in 1993 and 1994.

RESULTS

Positive associations between GI and changes in body weight (DeltaBW), percentage body fat (Delta%BF), and waist circumference (DeltaWC) were observed in women after adjustment for covariates. Significant GI x sex x physical activity interactions for DeltaBW, Delta%BF, and DeltaWC were observed, and the associations in the sedentary women were particularly positive. No significant associations with GI were observed in men, and no significant associations with GL were observed in either sex.

CONCLUSIONS

High-GI diets may lead to increases in BW, body fat mass, and WC in women, especially in sedentary women, which suggests that physical activity may protect against diet-induced weight gain. No associations with GI were observed in men, which suggests sex differences in the association between GI and obesity development.

Evaluation of a glucose meter for determining the glycemic responses of foods

BACKGROUND

Glucose meters are convenient for measuring postprandial glycemic responses. However, their performance for this purpose has not been evaluated.

METHODS

Glucose responses of 7 potato meals were measured using the One Touch Ultra(R) (OTU) glucose meter and a reference method (Yellow Springs Instruments Glucose Analyzer, YSI) and the incremental areas under the curves (AUC) and glycemic index (GI) values compared.

RESULTS

Mean AUC(OTU) was greater than AUC(YSI) (192+/-8 vs. 175+/-7 mmolxmin/l, p=0.001), but GI(OTU) tended to be less than GI(YSI) (69+/-3 vs. 74+/-3, p=0.052). Bland-Altman difference plots showed wide 95% limits of agreement for AUC (-84 to 119 mmolxmin/l) and GI (-21 to 26) values of individual subjects, and for the mean GI values of the 7 foods (-11 to 21). Total and error variance of AUC and GI values were greater for OTU than YSI, and food means differed significantly for YSI (p<0.01) but not OTU (p=0.11).

CONCLUSION

AUC and GI values determined by OTU are more variable and do not agree well with those obtained by YSI. Thus, the OTU is not recommended for determining AUC or GI in normal subjects. This conclusion does not necessarily apply to other glucose meters whose performance should be evaluated.