Table 3.

Main findings and possible limitations of each study.

No.	Citation	Main Findings	Possible Limitations
1.	Wolever et al. [21]	Low-GI diet with low-GI meals resulted in a lower postprandial glucose response in patients with T2D compared to a low-GI diet with high-GI meals (p < 0.001)	Researchers did not compare the acute effects of the high-GI diet vs. low-GI diet and the high-GI diet vs. low-CHO diet in the same participants
2.	Stenvers et al. [26]	(i) Replacing breakfast with a low-GR meal substitute or (ii) reducing the amount of CHO and increasing the amount of fiber resulted in a reduced postprandial glucose response in T2D patients	No effect was observed in the fasting glucose and hemoglobin A1c (HbA1c), possibly due to the low baseline HbA1c values
3.	Goncalves Reis et al. [23]	Dietary advice on low-GI diet resulted in a significant reduction of CHO content of the diet, which led to a significantly lower postprandial glucose response on the first day	(i)At the end of the 3-day trial, no statistical significant differences were found (ii)Short duration of the intervention; applied for 3 days per week
4.	Lobos et al. [29]	A low-GI breakfast, as opposed to a high-GI breakfast, resulted in significant greater reduction of postprandial glucose response in patients with T2D under IIT (p < 0.022)	(i)Small sample size (ii)90% of the sample corresponded to women, which decreases generalizability of the results (iii)Did not include measurements of insulin excursions
5.	Chang et al. [25]	(i)A low-CHO, high-fat breakfast where energy from CHO accounted for less than 10% energy lowered postprandial glucose excursions (p < 0.01); (ii)overall postprandial hyperglycemia and glycemic variability decreased with the low-carbohydrate diet (p < 0.03)	(i)Short duration of the intervention (ii)Research design did not include measurements of insulin excursions
6.	Silva et al. [28]	Plasma glucose, insulin, and ghrelin responses were least favorable for patients with T2D who consumed a high-GI and low-fiber diet (p < 0.005)	The tables of glycemic index were used to calculate GI instead of GI being determined from every food included in a meal
7.	Kamalpour et al. [27]	A low-calorie, reduced-CHO, and high-fiber diet was found to be beneficial and could improve fasting plasma insulin in poorly controlled T2D patients	No statistically significant differences observed regarding postprandial glucose and insulin levels, possibly due to sample size. Additionally, participants in the LoCarb group could not meet dietary advice, which resulted in smaller changes from baseline intakes
8.	de Carvalho et al. [30]	Increasing fiber content in breakfast, either from food or supplements, resulted in a lower postprandial glucose response (p < 0.05)	Insulin differences observed were not statistically significant. Additionally, participants had a good glycemic control at baseline, thus not permitting generalization of results
9.	Nisak et al. [22]	Postprandial glycemia and insulin responses were reduced after ingestion of a low-GI meal (p < 0.005)	Macronutrient content of the two test meals was not able to be kept identical, thus increasing possibility of confounding variables
10.	Imai et al. [24]	Dividing late night diner can significantly reduce postprandial hyperglycemia (p < 0.01)	The design of the study did not test the division of dinner in two meals with identical nutritional composition. The division resulted in a high-CHO meal, which was ingested first, and a high-protein, -fat, and -fiber meal, which was ingested approximately 3 h later; therefore, how consumption of the reverse nutritional composition would impact on postprandial hyperglycemia was left unknown

T2D-type 2 diabetes, GL-glycemic load; GI-glycemic index; CHO- carbohydrates.