Increasing dietary fiber intake for type 2 diabetes mellitus management: A systematic review

Table 1 Studies on acarbose to inhibit amylase in type 2 diabetes mellitus patients

Ref.	Population	Methods	Outcomes
Chen et al[8], 2023	17 Chinese T2DM patients, enrolled for 8 wk	Acarbose (100 mg; 3 times/d) + DF-rich diet; control group: Standard diet	Intervention resulted in decreased HbA1c, fasting glucose, and insulin sensitivity. No significant changes in the control group
Zhao et al[9], 2018	43 Chinese T2DM patients, enrolled for 11 wk	Acarbose (100 mg; 3 times/d) + DF-rich diet; control group: Standard diet	Intervention group showed sustained better glycemic control (HbA1c < 7%) for 89% of participants compared to the control. No significant differences in fasting glucose levels

T2DM: Type 2 diabetes mellitus; DF: Dietary fiber; Hb1Ac: Glycated hemoglobin.

Table 2 Studies with dietary fiber supplements in type 2 diabetes mellitus patients

Ref.	Population	Methods	Outcomes
Dall'Alba et al[10], 2013	44 Brazilian T2DM patients, enrolled for 6 wk	PHGG (10 g/d) + standard diet; control group: Standard diet	No significant changes in TG, HDL, SBP, or FG. Decreased waist circumference and HbA1c in the intervention group
Dehghan et al[11], 2014	49 Iranian T2DM patients, enrolled for 8 wk	Inulin (10 g/d) + standard diet; control group: Standard diet + maltodextrin (10 g/d)	Significant decreases in HbA1c (6.82 mmol/mol; 10.4%), and insulin in the intervention group
Dehghan et al[12], 2014	52 Iranian T2DM patients, enrolled for 8 wk	Oligofructose + inulin (10 g/d) + standard-diet; control group: Standard diet + maltodextrin (10 g/d)	HbA1c, FG, weight, and BMI significantly decreased in the intervention group
Gargari et al[13], 2015	60 Iranian T2DM patients, enrolled for 8 wk	Resistant starch (10 g/d) + standard diet; control group: Standard diet + maltodextrin (10 g/d)	Intervention group showed significantly decreased HbA1c (-0.3%; -3.6%), TG (-33.4 mg/dL, -15.4%), and SBP. HDL increased significantly only in the intervention group
Aliasgharzadeh et al[14], 2015	55 Iranian T2DM patients, enrolled for 8 wk	Resistant dextrin (10 g/d) + standard diet; control group: Standard diet + maltodextrin (10 g/d)	Fasted insulin, weight (-3.1 kg)z, and BMI (-1.4) significantly decreased in the intervention group. Decreased HbA1c was not significant in the intervention group
Farhangi et al[15], 2016	54 Iranian T2DM patients, enrolled for 8 wk	Resistant dextrin (10 g/d) + standard diet; control group: Standard diet + maltodextrin (10 g/d)	HbA1c and SBP decreased significantly in the intervention group. No significant changes were observed for BMI
Abutair et al[16], 2016	40 T2DM patients from Palestine, enrolled for 8 wk	Psyllium (10.5 g/d) + standard diet; control group: Standard diet + maltodextrin (10 g/d)	Significant changes were observed for glycemic control, including Hb1Ac and FG
Pedersen et al[17], 2016	40 T2DM patients from Ucraine, enrolled for 12 wk	Galacto-oligosaccharide (5.5 mg/d) + standard diet; control group: Standard diet + maltodextrin (5.5 g/d)	The prebiotic group showed increased HbA1c and fasting glucose
Farhangi et al[21], 2018	55 Iranian T2DM patients, enrolled for 8 wk	Resistant dextrin (10 g/d) + standard diet; control group: Standard diet + maltodextrin (10 g/d)	No significant changes were observed for glycemic control variables, and BMI, except for fasting insulin. Pro-inflammatory markers were significantly decreased in the intervention group
Birkeland et al[18], 2020	25 Norwegian T2DM patients, enrolled for 6 wk	Inulin fructans (16 g/d) + standard diet; control group: Standard diet + maltodextrin (16 g/d)	No changes in glycemic control were reported, with positive effects on fecal microbiome composition
Vuksan et al[22], 2020	26 Canadian patients (11 T2DM), enrolled for 3 wk	Viscous fiber blend + dietary fiber + standard diet; control group: Dietary fiber + standard diet + maltodextrin (16 g/d)	No significant effects on FG between groups. SBP and cardiovascular risk were reduced in the intervention group
Birkeland et al[19], 2021	25 Norwegian T2DM patients, enrolled for 6 wk	Inulin fructans (16 g/d) + standard diet; control group: Standard diet + maltodextrin (16 g/d)	No positive changes in glycemic control following a standard meal were reported
Birkeland et al[20], 2021	29 Norwegian T2DM patients, enrolled for 6 wk	Inulin fructans (16 g/d) + standard diet; control group: Standard diet + maltodextrin (16 g/d)	No positive changes in glycemic control or weight were reported
Su et al[22], 2022	13 Chinese T2DM patients, enrolled for 12 wk	Fiber consisted of probiotics, prebiotics, and whole grains, including three ready-to-consume prepared foods (44 g/d) + standard diet	The fiber formulation reduced Hb1Ac, weight, blood glucose, and blood pressure in T2D patients

PHGG: Partially hydrolysed guar gum; TG: Triglycerides; HDL: High-density lipoprotein; SBP: Systemic blood pressure; FG: Fasting glucose; BMI: Body mass index; Hb1Ac: Glycated hemoglobin.

Table 3 Studies with increased dietary fiber through diet in type 2 diabetes mellitus patients

Ref.	Population	Methods	Outcomes
Nowotny et al[24], 2015	59 German T2DM patients, enrolled for 8 wk	Intervention was increased DF (30-50 g/d); control group: Diet composed of ≤ 10 g/d DF	Both groups showed improved glycemic control and reduced weight
Belalcazar et al[35], 2014	1.701 American T2DM patients, enrolled for 48 wk	Intensive program increasing dietary fiber and physical activity, while also promoting caloric restriction	Positive changes in glycemic control, weight reduction, and other health parameters
Ziegler et al[25], 2015	30 German T2DM patients, enrolled for 8 wk	Intervention was increased DF (30-50 g/d); control group: Diet composed of ≤ 10 g/d DF	Both groups showed improved glycemic control and reduced weight. The magnitude of reduced Hb1Ac was higher in the DF intervention group
Li et al[36], 2016	298 Chinese T2DM patients, enrolled for 4 wk	Three intervention groups: Healthy diet (total DF = 33 g); 50 g oats (total DF = 36 g); and 100 g oats (total DF = 39 g); control group: Usual care without dietary changes	All intervention groups showed improved glycemic control and reduced weight. The magnitude of reduced Hb1Ac, FG, and BMI was higher in the DF intervention groups with increased DF intake
Gomes et al[26], 2017	20 Brazilian T2DM patients, enrolled for 4 wk	Compared two interventions: High glycemic diet and low GI diet	DF intake was not different between groups; the low glycemic diet induced reduced body fat, without changes in glycemic control in this study
Kondo et al[27], 2017	28 Japanese T2DM patients, enrolled for 8 wk	Compared two interventions: High fiber diet with brown rice and diet with white rice	Total DF intake increased only in the brown rice group. No differences in weight, body fat, and blood pressure were observed between the two groups. Fasting plasma glucose levels and Hb1Ac decreased in the brown rice diet group, but there was no statistically significant difference between the two groups
Tessari and Lante[28], 2017	22 Italian T2DM patients, enrolled for 96 wk	The intervention consisted in consuming a functional bread inducing increased DF intake. The control group received a regular bread	The intervention group showed improved Hb1Ac and post-prandial glucose. Body weight was increased in the intervention group, with no significant effects on other variables
Nguyen et al[29], 2019	49 Vietnamese T2DM patients, enrolled for 2 wk	Intervention consisted in Okara intake (resulting in 6 g of DF). The control received a standard diet	Intervention resulted in increased DF intake, promoting decreased FG and body weight
Yen et al[30], 2022	84 Indonesian T2DM patients, enrolled for 12 wk	Intervention consisted in increasing vegetable intake and DF intake. Control group received no counselling	Intervention with low glycemic diet induced reductions in HbA1C and body weight, and blood pressure parameters
Jenkins et al[31], 2022	134 Canadian T2DM patients, enrolled for 144 wk	Compared two interventions: Low GI diet and high fiber diet	Both interventions resulted in increased DF intake. However, low GI diet improved HB1Ac and body weight

DF: Dietary fiber; GI: Glycemic index; Hb1Ac: Glycated hemoglobin; FG: Fasting glucose; BMI: Body mass index.