Table 5.

Effects of HS consumption on blood glucose levels.

Country	Sex		Age (years)	Dose	Frequency/Days of Intervention	Sample Size		Design Study	Notes about Participants	Main Results	Ref.
	M	F				Exp.	CT
Infusion/Decoction/Tea
Indonesia	NI	NI	30–60	5 g	14 days	98	103	Q	Pre-diabetic women	HS significantly decreased fasting blood glucose levels with no effect on postprandial glucose	[127]
Indonesia	0	18	>60	2 g twice a day	21 days	9	9	Q, CT	Subjects with metabolic syndrome	Postprandial glucose and cortisol levels were significantly reduced in subjects > 60 years of age	[112]
USA	4	4	18–43	10 g	6 days	6	6	NI	One sample was collected per day for 6 days, 60 min after breakfast	HS together with a carbohydrate-rich breakfast appeared to slow the rate of increase in the glucose curve	[128]
Capsule/Tablet
Indonesia	NI	NI	35–65	1 g	8 weeks	30	30	Exp, DBT	The control group and the HS group presented homogeneous conditions	HS 500 mg 2 times a day can significantly reduce fasting blood glucose and insulin levels	[11]
Beverage
UK	NI	NI	49 ± 2	7.5 g	4 h	22	22	R, C, SB, CO		After 120 min of HS consumption, there was a tendency to a lower postprandial insulin response than the control group	[12]
Iran	22	38	52 (mean)	425 mg	8 weeks	30	30	R, DBT, PC	Of the participants in the study, 80% used insulin, and 20% used glucose-lowering drugs	HS did not promote changes in fasting blood glucose levels in patients with diabetic nephropathy	[13]
Cameroon	32	0	25.38 ± 3.35	35 g	2 weeks	32	0	NI	The preparation of the beverage granted contained sugar (180 g/L)	HS did not promote changes in blood glucose in healthy subjects aged 21 to 32 years	[121]

NI: no information; HS: Hibiscus sabdariffa; M: male; F: female; Exp: experimental group; CT: control group; Q: quasi-experimental; DBT: double-blind trial; C: controlled trial; SB: single-blind trial; CO: cross-over trial; R: randomized trial; PC: placebo control.