Dietary glycemic load, glycemic index, and refined grains intake are associated with reduced β-cell function in prediabetic Japanese migrants

Diet quality and its association with glycemic parameters in different diabetes progression stages. A cross-sectional questionnaire study at a primary care clinic

BACKGROUND

Diabetes mellitus is a leading cause of preventable deaths and becomes a major public health concern in Malaysia. Multiple studies have reported the association between diet quality and glycemic parameters among known diabetic subjects. Its influence in individuals with borderline diabetes (i.e. pre-diabetes) or unknown diabetes is still unclear.

OBJECTIVE

The objective of this study was to assess the association between diet quality evaluated by healthy eating index (HEI) with the glucose outcome in individuals with distinct diabetes progression stages, as well as to identify causal factors in relation to their diabetes status.

METHOD

A cross-sectional study was conducted at clinical care setting in Universiti Sains Malaysia (USM) between October 2018-March 2019. Normoglycemic controls (n = 47), at-risk of pre-diabetes (n = 58), pre-diabetes (n = 24) as well as individuals with undiagnosed diabetes (n = 18) were queried about their habitual diet by using Food Frequency Questionnaire (FFQ). Correlation analyses were performed to examine the relationship between HEI score and 1) Fasting plasma glucose (FPG) 2) postprandial blood glucose (2-HPP) and glycosylated hemoglobin (HbA1c). Multinomial regression was performed to identify predictors associated with diabetes status of study participants.

RESULT

Overall, diet quality of study participants was unsatisfactory with the mean score of 58.05 ± 9.07 that need improvement. Total HEI score was negatively correlated with the 2-HPP levels in pre-diabetic patients (r = - 0.45, p = 0.05). No significant association was revealed between glycemic parameters and total HEI score among other groups. Age, body mass index (BMI), triglycerides and female gender were positively correlated with the risk of pre-diabetes, at-risk of pre-diabetes and undiagnosed diabetes (p < 0.01).

CONCLUSION

Diet quality was not strongly associated with glycemic parameters among study participants. Age, BMI, triglycerides and female gender are crucial factors, that needed to be prioritized by primary care providers when managing pre-diabetes/diabetes to achieve possible reversion. Further in-depth investigations with large sample are warranted to confirm study findings.

The association between glycemic index, glycemic load, and metabolic syndrome: a systematic review and dose-response meta-analysis of observational studies

PURPOSE

The association of glycemic index (GI) and glycemic load (GL) with metabolic syndrome (MetS) is controversial. Therefore, we conducted this first systematic review and dose-response meta-analysis of observational studies to quantify these associations.

METHODS

We searched PubMed, EMBASE, Web of Science, and the Cochrane Library for relevant studies up to 1 April 2019. Summary odds ratios (OR) and 95% confidence intervals (CI) were calculated by a random-effects model. This study was registered with PROSPERO (CRD42019131788).

RESULTS

We included eight high-quality (n = 5) or medium-quality (n = 3) cross-sectional studies in the final meta-analysis, comprising 6058 MetS events and 28,998 participants. The summary ORs of MetS for the highest versus lowest categories were 1.23 (95% CI 1.10-1.38, I² = 0, tau² = 0, n = 5) for dietary GI, 1.06 (95% CI 0.89-1.25, I² = 36.2%, tau² = 0.0151, n = 6) for dietary GL. The summary OR was 1.12 (95% CI 1.00-1.26, I² = 0, tau² = 0, n = 3) per 5 GI units, 0.96 (95% CI 0.83-1.10, I² = 33.4%, tau² = 0.0059, n = 2) per 20 GL units.

CONCLUSIONS

Dietary GI was positively associated with the prevalence of MetS. However, no significant association was found between dietary GL and the prevalence of MetS. Further studies with prospective design are needed to establish potential causal relationship between dietary GI and the MetS.

Dietary assessment of pre-diabetic patients by using food frequency questionnaire. A systematic review of study quality, study outcome, study questionnaire and their relative validity and reliability

BACKGROUND

The contribution of dietary factors in the development and progression of pre-diabetes has been increasingly recognized. However, due to high variability in dietary habits measurement of dietary intake remains one of the most challenging tasks in this population. Food frequency questionnaire (FFQ) which investigates usual dietary intake can be used to identify frequent consumption of foods such as dietary fat, fiber, grains that are linked to the risk of pre-diabetes.

METHOD

This systematic review was conducted to identify and describe FFQs that measure dietary intake of pre-diabetic patients and to examine their relative validity and reliability. The systematic search was done through electronic databases such as PubMed, CINAHL, PsycINFO, ProQuest and Scopus. Methodological quality of included studies and results of study outcome was also summarized in this review.

RESULT

The search identified 445 papers, of which 18 studies reported 15 FFQs, met inclusion criteria. Most of the FFQs (n = 12) were semi-quantitative while three were frequency measures with portion size estimation of selected food items. Test-retest reliability of FFQ was reported in 7 (38.3%) studies with the correlation coefficient of 0.33-0.92. Relative validity of FFQ was reported in 16 (88.8%) studies with the range of correlation coefficient of 0.08-0.83. Dietary patterns rich in carbohydrate, fat, animal protein and n-3 fatty acids were associated with increased risk of pre-diabetes.

CONCLUSION

No well-established disease-specific FFQ identified in the literature. Development of a valid, practical and reliable tool is needed for better understanding of the impact of diet in pre-diabetic population.

Associations between Dietary Patterns and Impaired Fasting Glucose in Chinese Men: A Cross-Sectional Study

Few studies have examined the association between Asian dietary pattern and prediabetes, in particular, the Chinese diet. We conducted a cross-sectional study to identify dietary patterns associated with impaired fasting glucose (IFG) which considered a state of prediabetes in Chinese men. The study included 1495 Chinese men aged 20 to 75 years. Information about diet was obtained using an 81-item food frequency questionnaire (FFQ), and 21 predefined food groups were considered in a factor analysis. Three dietary patterns were generated by factor analysis: (1) a vegetables-fruits pattern; (2) an animal offal-dessert pattern; and (3) a white rice-red meat pattern. The multivariate-adjusted odds ratio (OR) of IFG for the highest tertile of the animal offal-dessert pattern in comparison with the lowest tertile was 3.15 (95% confidence intervals (CI): 1.87-5.30). The vegetables-fruits dietary pattern was negatively associated with the risk of IFG, but a significant association was observed only in the third tertile. There was no significant association between IFG and the white rice-red meat pattern. Our findings indicated that the vegetables-fruits dietary pattern was inversely associated with IFG, whereas the animal offal-dessert pattern was associated with an increased risk of IFG in Chinese men. Further prospective studies are needed to elucidate the diet-prediabetes relationships.

Dietary carbohydrate dictates development of Type 2 diabetes in the Nile rat

Amount and type of dietary carbohydrate (CHO), as well as the CHO:fat ratio, are thought to be critical for both the rate of development and severity of Type 2 diabetes mellitus. Thus, these nutritional considerations were examined in the previously described "spontaneous" model of diabetes and metabolic syndrome, the Nile rat. Weanling male Nile rats (n=92) were fed semipurified diets, modifying glycemic index and load by changing the amount of fiber or altering the CHO:fat ratio. Random and fasting blood glucose and body weight were assessed, and diabetes was characterized in terms of blood glucose, relevant plasma and liver parameters, food and water intake and terminal organ weights. Nile rats fed with hiCHO became more hyperglycemic than rats fed with modCHO (P<.05), while loCHO and hiCHO+hiFiber rats remained essentially normoglycemic. Liver lipid and glycogen accumulation was associated with severe hyperlipemia in diabetic rats, analogous to metabolic syndrome in humans. Advanced diabetes was linked to liver and kidney damage and elevated blood urea nitrogen with weight loss. Dispersing dietary CHO by fiber or replacing it by moderate fat (reducing the glycemic index and load) delayed the onset of diabetes but did not prevent signs of insulin resistance. A very low content of dietary CHO (high fat) seemed to prevent even these early indicators of insulin resistance. Thus, the Nile rat represents a novel CHO-sensitive model for study of Type 2 diabetes that reliably follows the course of disease in humans.

Optimal energy distribution of carbohydrate intake for Japanese elderly patients with type 2 diabetes: the Japanese Elderly Intervention Trial

AIM

In diet therapy for diabetes, optimal energy intake and the energy distribution of macronutrients (protein : fat : carbohydrate [PFC] energy ratio) are important. We aimed to clarify the correlation between the PFC energy ratio and metabolic parameters including glycated hemoglobin A1c (HbA1c) and triglycerides in Japanese elderly patients with type 2 diabetes mellitus aged 65 years or older.

METHODS

Participants were 1173 diabetic patients aged 65 years or older with serum HbA1c level of >/=7.4% enrolled in the Japanese Elderly Diabetes Intervention Trial (J-EDIT). The participants were divided into four groups by the percentage of total energy intake (%E) of carbohydrate (C1: less than 55%E, C2: 55%E or more and less than 60%E, C3: 60%E or more and less than 65%E, and C4: 65%E or more). Relations of %E of carbohydrate to HbA1c and other metabolic parameters, energy intake and nutritional intake were examined. Furthermore, the subjects were divided into four categories by HbA1c levels by quartile method (Q1: less than 7.90%, Q2: 7.90% or more and less than 8.30%, Q3: 8.30% or more and less than 8.80%, Q4: 8.80% or more). Relations of HbA1c to other metabolic parameters, energy intake and nutritional intake were examined.

RESULTS

The mean HbA1c levels in the four groups were C1: 8.40%, C2: 8.50%, C3: 8.41% and C4: 8.36% in men, and C1: 8.51%, C2: 8.47%, C3: 8.35% and C4: 8.52% in women, respectively. There were no significant differences and linear trend in HbA1c levels across groups. The mean triglyceride levels were in the range of 122-128 mg/dL in men from C1 to C3, although it was significantly higher in C4 (177 mg/dL). The mean triglyceride levels were in the range of 128-136 mg/dL in women from C1 to C3, although it was significantly higher in Q4 (150 mg/dL). Amounts of protein and fat intakes decreased with an increase of %E of carbohydrate, although amount of carbohydrate intake did not change significantly. As a result, %E of protein and fat, and energy intake decreased in both men and women with an increase in %E of carbohydrate. Among the four quartiles divided by HbA1c levels, there were no significant differences in energy intake and PFC energy ratio.

CONCLUSIONS

The present study suggests that, within the range studied, the carbohydrate energy ratio has no correlation with HbA1c levels. However, serum triglyceride levels increased and high-density lipoprotein cholesterol levels decreased significantly, with an increase of %E of carbohydrate in men, and the same tendencies were observed in women. Furthermore, in patients with 65%E or more of carbohydrate, serum triglyceride levels exceeded 150 mg/dL, which is the recommended treatment target for diabetic patients. These results suggest that the ideal %E of carbohydrate for Japanese elderly type 2 diabetes is less than 65. The lower limit of %E of carbohydrate could not be determined from the present study.