| Objective:How to manage the blood glucose in a good level and keep it steady is of paramount importance of diabetes disease management.Blood glucose is particularly affected by diet,and an accurate understanding of the body’s blood glucose response to food is helpful to guide patients to eat.Glycemic index(GI)is a physiological parameter which is associated with the body’s blood glucose response to the given food.Many studies have shown that low GI diet can significantly improve the condition of diabetic patients and reduce the risk of cardiovascular disease.GI values of foods rich in dietary fiber are often low,and increasing dietary fiber intake is also beneficial to diabetic patients.Now,"Food products-Determination of the glycemic index and recommendation for food classification(ISO 26642:2010)" is the general standard for GI determination in the world,but some procedures are still not strictly defined,which may lead to deviation of the GI results and even improper classification.What’s more,the development of continuous glucose monitoring system(CGMS)has brought great convenience for clinicians to accurately observe the fluctuation of patients’ blood glucose,especially the real-time changes of blood glucose before and after meals.So,how to use the stable ISO standard method to determine GI of food and observe the effect caused by food on the blood glucose in healthy individuals at the same time and how to use the CGMS to analyze the changes of blood glucose caused by diet for diabetic patients are both helpful to clarify the exact influence of food on blood glucose and facilitate the clinical decision-making for nutritionists.Contents:Established the stable methodology based on ISO 26642:2010 and determined GI of fiber-rich instant rice and ordinary instant rice according to it.Observed the postprandial blood glucose response of the two kinds of instant rice in healthy people.Then,combined with CGMS,a randomized controlled double-blind study was conducted on patients with type 2 diabetes mellitus(T2DM),to explore the difference of the effects of different instant rice on glycolipid metabolism and blood glucose fluctuation,and to analyze the possible mechanism,so as to provide reference for individualized nutrition intervention of diabetes mellitus.Methods:Part Ⅰ:Based on ISO 26642:2010 standard and literature review,more than 10 homogeneous healthy adults were included.Using 50g anhydrous glucose as the reference to calculate the amount of instant rice containing the same amount of available carbohydrates.With automatic biochemical analyzer,the glucose concentration of fingertip capillary plasma was measured,and then the incremental area under the glycemic curve(IAUC)in 120min and GI were calculated,and the postprandial glucose response was observed also.Part Ⅱ:Patients with T2DM whose course of disease was≥1 year,with a stable condition,overweight or obese were taken as the study objects,and a four-week randomized controlled double-blind diet intervention was conducted.After collecting patients’ general data and measuring blood biochemical indicators at baseline,the patients were randomly divided into study group(intervention with fiber-rich instant rice)and control group(intervention with ordinary instant rice).Patients were required to eat instant rice 80g/d as independent staple food or a supplement of daily staple food.During the period,CGMS was used to monitor multiple blood glucose levels within 180min before and after three meals a day for two weeks combined with the 3*24-hour dietary review method(3rd～4th week).Four weeks later,the changes of glycosylated albumin(GA)level were taken as the primary outcome measure,and the changes of fasting plasma glucose(FPG),blood lipid profile(TC,TG,LDL-C,HDL-C),insulin profile(FIns,HOMA-IR,HOMA-β)and visceral adipose tissue estimation(eVAT)were taken as the secondary outcome measures to reflect the effect of the diet intervention on glycolipid metabolism in T2DM.At the same time,patients with complete blood glucose records were included to reflect the influence of different dietary interventions on blood glucose fluctuation.The daily standard deviation of blood glucose(SD),coefficient of variation(CV),largest amplitude of glycemic excursions(LAGE),mean amplitude of glycemic excursions(MAGE,aMAGE)and the time in range of glucose(TIR,%)were taken as assessment of within-day blood glucose variability and the fasting plasma glucose coefficient of variation(FPG-CV)and the absolute means of daily differences(MODD)were taken as assessment of day-to-day blood glucose variability.Also,we analyzed the different influence of fiber-rich instant rice on postprandial blood glucose response compared with common daily staple food,so as to comprehensively explore the influence of intervention measures on short-term metabolic outcome of T2DM patients.Results:1.Part I:Ten people each tested fiber-rich instant rice and ordinary instant rice.The GI of fiber-rich instant rice and ordinary instant rice were(65.9±6.6)and(75.1±8.6)respectively,with average CV=3.4%.Compared with ordinary instant rice,IAUC was smaller in 120min after eating fiber-rich instant rice in healthy people,and the fluctuation excursion of blood glucose reduced also,and the fluctuation trend of postprandial blood glucose response curve was gentler,which meant it suitable for diabetic patients to eat.2.Part Ⅱ:① Sixty-one T2DM patients were randomized(30 patients in the study group).Fifty-three patients(dropping rate about 13.1%)completed all the study,and no serious adverse events occurred;The baseline data of the two groups were comparable,and there was no significant difference in dietary nutrient intake and energy supply ratio during 4 weeks,but the dietary fiber intake of the study group was higher than that of the control group,and the difference was statistically significant(P<0.05).②PP analysis:GA decreased more in the study group,but there was no significant difference between the two groups(P=0.112).Compared with baseline,the level of GA in the study group decreased significantly(P=0.008),while there was no significant decrease in the control group.TC,LDL-C decreased more in the study group,and the difference between the two groups was statistically significant(P=0.008,0.032),while there were no significant differences of the changes of FPG,TG,HDL-C between the two groups(all P>0.05).Compared with baseline,the levels of TC and LDL-C in the study group decreased significantly after intervention(P=0.006,0.020),while there was no significant decrease in the control group.There was no significant difference of FPG,TG and HDL-C before and after intervention in both groups.There was no significant difference in the changes of FIns.HOMA-IR and HOMA-β between groups.Compared with the baseline level,HOMA-β in the control group was significantly higher after the intervention(P=0.035).There was no significant difference between groups in the change of eVAT.Compared with the baseline level,the eVAT in control group was significantly lower after the intervention(P=0.049).ITT analysis:GA in study group decreased more,and there was no significant difference between groups(P=0.118).GA levels decreased significantly from baseline in the study group(P=0.008)and were not significantly decreased in the control group.TC and LDLC decreased more in the study group,and the differences were statistically significant between groups(P=0.012 and 0.034).Compared with the baseline,the levels of TC,LDLC and LDL-C/HDL-C in study group decreased after intervention,and the differences were statistically significant(P=0.006,0.020 and 0.024);no significant decrease was noticed in the control group.③ The blood glucose records showed that the daily dietary nutrient intake of the groups during the blood glucose monitoring was comparable.The dietary fiber intake of the study group was higher than that of the control group,and the difference was statistically significant in the 4th week(P<0.05).The fluctuation of daily blood glucose in the 3rd week was similar between the two groups.The daily blood glucose CV,LAGE,MAGE,and aMAGE in the study group on the 1st day of the 4th week were higher than those in the control group,and the differences were statistically significant(P=0.030,0.015,0.048,and 0.038).However,there was no statistically significant difference in TIR between the groups,and all of them met the standard by more than 70%.There was no significant difference in weekly FPG-CV or MODD between the two groups.The fluctuation of blood glucose in the study group generally tended to improve during the monitoring period.④ Compared with common daily staple food:when T2DM patients take fiber-rich instant rice as their only staple food,IAUC is lower in 120min,but the difference is not statistically significant(P=0.055).The area under the glycemic curve(AUC)in 60min,120min and 180min is lower also,and the difference is statistically significant(P=0.006,0.007 and 0.020).The spike of postprandial blood glucose was lower after eating fiber-rich instant rice(P=0.013).The postprandial of glycemic excursions(PPGE)was lower after eating fiber-rich instant rice(P=0.044).And the postprandial blood glucose response curve of fiber-rich instant rice "rose slowly and fell slowly".The blood glucose curve rose more slowly,and the spike appeared more later,with the peak value of(7.3±1.7)mmol/L at 120min,and then gradually decreased to(7.0±1.7)mmol/L at 180min.Conclusion:Based on the ISO 26642:2010 standard,this study measured the GI of instant rice,and observed that fiber-rich instant rice was beneficial to reduce the increase of blood glucose after meals,and was suitable for diabetic patients.In addition,a randomized controlled double-blind dietary intervention was conducted in overweight/obese T2DM patients,and it was found that fiber-rich instant rice could improve lipid metabolism and blood glucose fluctuation of patients,which provided evidence for nutritional intervention of diabetes,and also is helpful to analyze the influence of food’s characteristics on blood glucose,which can further promote its clinical application. |
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