diabetes mellitus is a metabolic disorder resulting from a defect in insulin secretion , insulin activity , or both .
the growing prevalence of type 2 diabetes is associated with the obesity epidemic , and diagnosis is occurring at increasingly younger ages .
the major goal of type 2 diabetes management is to better regulate the blood sugar and prevent or slow the development of complications , such as retinopathy , nephropathy , neuropathy and cvd .
numerous studies have demonstrated dietary intervention is a critical factor in type 2 diabetes management .
some researchers have recommended low - glycemic index ( gi ) diets as a strategy for improving diabetes .
the gi of foods is defined as the carbohydrates in different foods measured according to time - integrated effect on postprandial glycemia .
foods with high gi are more rapidly digested and absorbed , so they result in higher postprandial blood glucose levels per unit of carbohydrate and a faster rise in blood glucose levels than do foods with lower gi .
research on gi has shown that different carbohydrate foods produce significantly different glycemic responses and postprandial glycemic excursions .
this is important in the context of diabetes management , because excessive rise in postprandial glycemia puts patients with diabetes at greater risk of developing complications .
similarly , peak incremental indices ( pii ) are also used to evaluate postprandial glycemia and the glycemic effects of different foods .
jennie et al . studied the use of low gi diets for the management of diabetes .
they found that low gi diets improved overall glycemic control in individuals with diabetes , as assessed by gi and pii .
demonstrated that better daily control of blood glucose excursions , especially in the postprandial period , could be a predictor of the rate of diabetic complications , independent of hba1c levels , in patients with type 2 diabetes .
in addition , the american diabetes association has suggested that the use of low - gi foods may reduce postprandial hyperglycemia .
s study the gi values of glucose , fructose and sucrose are 103 , 15 and 65 , respectively .
several studies have shown that the different amount and percentage of monosaccharides , disaccharides and dietary fiber in fruit will affect its gi value .
although gi and pii are two widely - used methods to evaluate the postprandial glycemia and glycemic effects of different foods , little research has been done on whether there is any difference between the gi values and pii in healthy subjects and type 2 diabetes patients .
this study aimed to measure and compare the gi and pii of six kinds of fruit in healthy subjects and patients with type 2 diabetes in taiwan .
twenty healthy non - diabetic people with a mean age of 21.9 years , and 17 patients with type 2 diabetes and a mean age of 57.5 years , were enrolled in this study . for type 2 diabetes patients ,
the exclusion criteria were as follows : hba1c level higher than 7.5% ; complications , such as nephropathy ; and insulin - dependence .
in addition , subjects were excluded if they were smokers , taking prescription medication , and dieting .
the study was approved by the institutional review board of taipei medical university hospital and written informed consent was obtained from every subject .
the characteristics of all subjects are listed in table 1 and 2 . following a study by wu , we choose two kinds of fruit : grapes ( with a higher gi value : 49.1 ) and asian pears ( with a lower gi value : 18.0 ) as our test fruits .
in addition , the cognition of fruits of type 2 diabetes patients will affect their choice for fruits . in this study
, we wanted to know the type 2 diabetes patients attitudes toward various fruits in taiwan .
so , the 17 type 2 diabetes patients were asked to fill out a questionnaire about their attitudes toward various fruits .
this questionnaire listed most popular fruits in taiwan , and the type 2 diabetes subjects had to answer 
what are the fruits that type 2 diabetes patients can not eat , in your opinion 
what are the fruits that type 2 diabetes patients can eat , in your opinion 
based on the results of the questionnaire , we chose four kinds of fruit as the test fruits ( two  can not eat  , and two  can eat  fruits ) .
thus , the gi and pii of a total of six fruits were included in this study for measurement of gi and pii .
the gi values of the six fruits were tested according to the standard gi testing protocol [ http://www.saiglobal.com/shop/script/details.asp?docn=as0733779662at ] ; the reference food was 50  ml 50% glucose solution ( 25  g glucose ) .
briefly , on each test day , all subjects consumed fruit containing 25  g carbohydrates with 100  ml water in 15  min .
one edible portion of fruit that contained 25  g carbohydrates was calculated using the amount of carbohydrates listed for each in the taiwanese nutrient database [ http://www.doh.gov.tw/foodanalysis/ingredients.htm ] .
venous blood was sampled in a heparin - containing tube at 0 ( start of ingestion ) , 30 , 45 , 60 , 90 and 120  min after ingestion .
blood samples were centrifuged ( 1400    g for 10  min at 4c ) to obtain plasma .
blood sugar was measured using a commercial kit ( glucose oxidase and peroxidase , randox lab - ltd . ) . to calculate gi values , the area under curve ( auc )
auc refers to the area included between the baseline and incremental blood glucose points when connected by straight lines .
the gi of a food is identified as : the area under the glycemic curve of the test food / area under the glycemic curve of glucose . for pii calculation
, pii is defined as the ratio of the maximal increment of plasma glucose produced by tested fruits to that produced by glucose .
the formula is as follow : maximal increment produced by the test food / maximal increment produced by glucose ( maximal increment means the difference between the peak point and the fasting point ) .
the results were analyzed by analysis of variance ( anova ) and student s t test using spss .
the results are presented as mean    sd or mean    sem .
twenty healthy non - diabetic people with a mean age of 21.9 years , and 17 patients with type 2 diabetes and a mean age of 57.5 years , were enrolled in this study . for type 2 diabetes patients ,
the exclusion criteria were as follows : hba1c level higher than 7.5% ; complications , such as nephropathy ; and insulin - dependence .
in addition , subjects were excluded if they were smokers , taking prescription medication , and dieting .
the study was approved by the institutional review board of taipei medical university hospital and written informed consent was obtained from every subject .
the characteristics of all subjects are listed in table 1 and 2 . following a study by wu , we choose two kinds of fruit : grapes ( with a higher gi value : 49.1 ) and asian pears ( with a lower gi value : 18.0 ) as our test fruits .
in addition , the cognition of fruits of type 2 diabetes patients will affect their choice for fruits . in this study
, we wanted to know the type 2 diabetes patients attitudes toward various fruits in taiwan .
so , the 17 type 2 diabetes patients were asked to fill out a questionnaire about their attitudes toward various fruits .
this questionnaire listed most popular fruits in taiwan , and the type 2 diabetes subjects had to answer 
what are the fruits that type 2 diabetes patients can not eat , in your opinion 
what are the fruits that type 2 diabetes patients can eat , in your opinion 
based on the results of the questionnaire , we chose four kinds of fruit as the test fruits ( two  can not eat  , and two  can eat  fruits ) .
thus , the gi and pii of a total of six fruits were included in this study for measurement of gi and pii .
the gi values of the six fruits were tested according to the standard gi testing protocol [ http://www.saiglobal.com/shop/script/details.asp?docn=as0733779662at ] ; the reference food was 50  ml 50% glucose solution ( 25  g glucose ) .
briefly , on each test day , all subjects consumed fruit containing 25  g carbohydrates with 100  ml water in 15  min .
one edible portion of fruit that contained 25  g carbohydrates was calculated using the amount of carbohydrates listed for each in the taiwanese nutrient database [ http://www.doh.gov.tw/foodanalysis/ingredients.htm ] .
venous blood was sampled in a heparin - containing tube at 0 ( start of ingestion ) , 30 , 45 , 60 , 90 and 120  min after ingestion .
blood samples were centrifuged ( 1400    g for 10  min at 4c ) to obtain plasma .
blood sugar was measured using a commercial kit ( glucose oxidase and peroxidase , randox lab - ltd . ) . to calculate gi values , the area under curve ( auc )
auc refers to the area included between the baseline and incremental blood glucose points when connected by straight lines .
the gi of a food is identified as : the area under the glycemic curve of the test food / area under the glycemic curve of glucose . for pii calculation
, pii is defined as the ratio of the maximal increment of plasma glucose produced by tested fruits to that produced by glucose .
the formula is as follow : maximal increment produced by the test food / maximal increment produced by glucose ( maximal increment means the difference between the peak point and the fasting point ) .
the results were analyzed by analysis of variance ( anova ) and student s t test using spss .
the results are presented as mean    sd or mean    sem .
table  1 and 2 showed the characteristics of healthy and type 2 diabetes subjects .
healthy non - diabetic people with a mean age of 21.9 years , and patients with type 2 diabetes have a mean age of 57.5 years . in fasting blood glucose level aspect ,
the fasting blood glucose level in healthy non - diabetic people is 87.8    5.0  mg / dl , significantly lower than that in patients with type 2 diabetes ( 122.0    27.5  mg / dl ) .
there are no significantly differences of height , weight , bmi and body fat between two groups . in the questions regarding type 2 diabetes ,
the fruits that type 2 diabetes patients can not eat , in my opinion  were lychees , longan , custard apples , bananas and mangos .
the top five fruits they identified as  the fruits that type 2 diabetes patients can eat , in my opinion  were guava , golden kiwifruit , tomatoes , apples and dragon fruit . based on these results
, we chose guavas , golden kiwifruit , lychees and bananas as our other four kinds of test fruits .
the gi value of six kinds of fruits : grapes , asian pears , guavas , golden kiwifruit , lychees and bananas in all subjects are listed in table  3 . the gi value of grapes , asian pears , guavas , golden kiwifruit , lychees and bananas in type 2 diabetes subjects was 49.0    4.5 , 25.9    2.9 , 32.8    5.2 , 47.0    6.5 , 60.0    8.0 and 41.3    3.5 , respectively . in healthy subjects ,
the gi value of these six fruits was 49.1    7.3 , 18.0    5.4 , 31.1    5.1 , 47.3    12.1 , 47.9    6.8 and 35.1    5.6 , respectively .
there was no significant difference between healthy subjects and those with type 2 diabetes in the gi values of these six fruits .
the postprandial glycemia curves for each fruit in healthy and type 2 diabetes subjects are shown in fig .  1 .
the peak points of postprandial glycemia were very similar in healthy and type 2 diabetes subjects after 30 to 45  min .
however , in type 2 diabetes subjects , the rate of reduction of postprandial glycemia was slower than in healthy subjects , and the blood sugar in most of the type 2 diabetes patients returned to fasting level about within 120  min .
the pii of healthy and type 2 diabetes subjects are listed in table  4 .
we found no significant difference between healthy and type 2 diabetes subjects in the pii for these six fruits .
the weather in taiwan is excellent for growing fruit , so fruit is a very popular part of the taiwanese diet .
carbohydrates are major components of fruits , especially monosaccharides ( glucose , fructose ) , disaccharides ( sucrose ) and dietary fiber .
atkinson et al.s study measured the gi value of glucose , fructose and sucrose as 103 , 15 and 65 , respectively .
in addition , nilsson et al . showed that the foods with lower gi contained more dietary fiber and resistant starch .
trinidad et al . found that there was a negative association between the dietary fiber level in food and its gi value .
thus , the different proportions of monosaccharides , disaccharides and dietary fiber in fruit will affect its gi values and postprandial glycemic effects .
for type 2 diabetes patients , chosing fruit correctly is important for the control of blood sugar .
thus , this study aimed to evaluate the gi and pii of six popular kinds of fruit consumed in taiwan and to compare them in healthy and type 2 diabetes subjects . foods with low gi produce lower postprandial blood sugar levels and a lower overall blood sugar response than do foods with a high gi .
the american diabetes association suggests that type 2 diabetes patients consume more low gi foods to help optimize glycemic control .
reduced insulin secretion and decreased insulin sensitivity are the major causes of type 2 diabetes .
schulze et al . showed that diets with higher gi and lower levels of dietary fiber are associated with greater risk of type 2 diabetes .
two studies also found a positive correlation between gi in the diet and fasting blood sugar , fasting triglycerides and insulin , bmi , and homa ( homeostasis model assessment ) levels .
proved that lifestyles including a high gi diet long term increase the volume of -cells and the secretion of insulin .
according to a study by lebovitz , abnormal postprandial blood sugar levels are an early symptom of the development of type 2 diabetes .
also found that postprandial blood sugar could be an independent indicator of the complications from type 2 diabetes .
similar to gi values , pii has also been used to evaluate postprandial glycemia and glycemic effects of different foods in a study by abdulrhman et al . using these methods
, our study found that in healthy subjects , blood sugar returned to fasting level within sixty minutes .
however , in type 2 diabetes subjects , the rate of postprandial glycemia reduction is slower than in healthy subjects , and blood sugar in most of the diabetes patients returned to fasting level within about 120  min , but not for everyone .
this situation could constitute a limitation affecting gi calculations . because of their abnormal physiology , it is difficult for type 2 diabetes patients to fast longer than 120  min during the gi testing protocol .
however , if the blood sugar did not return to fasting level within 120  min , the auc during the period from 90 to 120  min post - ingestion will be underestimated , which could affect the accuracy of gi measurement . in the contrast
, pii is calculated based on the ratio of the maximal increment of plasma glucose produced by tested foods to that produced by reference foods , and is not based on the auc , therefore calculation of pii is not subject to the same kind of limitation .
we recommend that to reduce bias , gi and pii should be considered together when evaluating the postprandial glycemia and glycemic effect of different foods . in this study , we found no significant difference in gi and pii of six kinds of fruits when consumed by healthy and type 2 diabetes subjects .
abdulrhman et al.s study compared the gi and pii of honey , sucrose and glucose in 20 patients with type 1 diabetes and 10 healthy subjects . in their study
the gi of sucrose in healthy and type 1 diabetes subjects was 1.32 and 1.19 , respectively , while that of honey was 0.69 and 0.61 .
the pii of sucrose in healthy and type 1 diabetes subjects was 1.25 and 1.10 , respectively , while that of honey was 0.61 and 0.60 .
they concluded that the gi and pii of either sucrose or honey did not differ significantly between type 1 diabetes patients and healthy subjects .
they demonstrated that both gi and pii are approximately the same in diabetics and non - diabetics .
a study by samnata et al . that measured the gi and pii of glucose , sucrose and honey in 12 healthy subjects , eight patients with insulin - dependent diabetes mellitus and six patients with non - insulin - dependent diabetes mellitus .
they likewise found no remarkable difference between the healthy and diabetic patients in gi and pii .
similarly , our results showed , the gi and pii of six kinds of fruits are the same in healthy and type 2 diabetes subjects .
so we think that the gi and pii of foods in the healthy subjects could be applied to the diabetes patients . in conclusion
, it may be expected that both gi and pii will be approximately the same in both type 2 diabetics and healthy subjects .
so we think that the gi and pii of foods in the healthy subjects could be applied to the diabetes patients .
 the aim of this study was to evaluate the glycemic index and peak incremental indices of six popular fruits in taiwan , comparing healthy subjects ( n  =  20 ) and patients with type 2 diabetes ( n  =  17 ) . 
 the six kinds of fruits tested were grapes , asian pears , guavas , golden kiwifruit , lychees and bananas . 
 glycemic index values were tested according to the standard glycemic index testing protocol . 
 the glycemic index and peak incremental indices were calculated according to published formulas . in type 2 diabetes subjects , the glycemic index values of grapes , asian pears , 
 guavas , golden kiwifruit , lychees and bananas were 49.0    4.5 , 25.9    2.9 , 32.8    5.2 , 47.0    6.5 , 60.0    8.0 and 41.3    3.5 . in healthy subjects , 
 the glycemic index values were 49.1    7.3 , 18.0    5.4 , 31.1    5.1 , 47.3    12.1 , 47.9    6.8 and 35.1    5.6 . 
 there was no significant difference in glycemic index values between healthy and type 2 diabetes subjects . 
 there was also no significant difference in pii when comparing healthy subjects and subjects with type 2 diabetes . in conclusion , 
 glycemic index and peak incremental indices in healthy subjects can be approximately the same for type 2 diabetes . 
Introduction
Materials and Methods
Subjects
Statistics
Results
Discussion