*4.2. Meta-Analysis*

The Review Manager (RevMan) 5.3 software [34] was used to conduct the metaanalysis. The measure of heterogeneity was the I<sup>2</sup> statistic [30], and statistical significance of heterogeneity was set at p < 0.10. The fixed effects model was used when heterogeneity was not important (I2: 0–40%) and the random effects model was applied when heterogeneity was substantial or considerable (I2: 40–100%) [30]. The SMD was used for the meta-analysis.

A subgroup analysis was carried out to examine the effect of prebiotics and oral antidiabetic agents in patients with T2D.

#### *4.3. Effect Size*

The result of the meta-analysis are depicted as forest plots and in terms of statistical significance, *p* < 0.05 was used to assess the overall effect of the intervention.

#### **5. Results**

Sixteen studies were included in the systematic review, while fourteen studies were included in the Network meta-analysis (Figure 1). The characteristics of the included studies including countries where studies were conducted, type of study, participants, sample size, mean age, mean diabetes duration, interventions and results/findings are outlined in Table 2. Four studies were carried out in China, three in Italy and two studies in Mexico. One study each was carried out in Japan, Korea, Norway, Canada, Netherlands, UK and Spain. All these studies were randomised controlled studies.

The network plots of the Network meta analysis can be found in the supplementary file (Figure S1 and Table S1).


**Table 2.** Description and characteristics of studies included.


**Table 2.** *Cont.*


**Table 2.** *Cont.*



Abbreviations: BMI: Body Mass Index; T2D—type 2 diabetes; Ma-Pi —macrobiotic diet; FBG—fasting blood glucose; PBG—post-prandial blood glucose; HbA1c—glycated haemoglobin; GOS—galacto-oligosaccharides; AMC—an herbal formula consisting of eight herbs; HOMA-IR—homeostatic model assessment of insulin resistance; DP—dietary portfolio; SB—scutellaria baicalensis; SCFA—short chain fatty acids; PGX—PolyGlycopleX, a highly viscous polysaccharide complex; NBS—native banana starch; HMS—high-amylose maize starch; DMS—digestible maize starch; GC—glycemic control; GV—glycemic variability; BA—bile acid; BW—body weight; SGLT2—sodium-glucose-linked transporter-2.
