1. Overview of study populations.

Study ID (design)	Intervention(s) and comparator(s)	Description of power and sample size calculation	Screened/eligible (N)	Randomised (N)	Analysed (primary outcome) (N)	Finishing study (N)	Randomised finishing study (%)	Follow‐up
Chlup 2009 (cross‐over non‐RCT)	I: buccal treatment: 10 glucose spray doses (five doses on the mucosa of each cheek, without swallowing), buccal	—	16 participants with full cross‐over	NA	16	16	NA	NA
	C: oral treatment: dextrose tablet to be chewed (only these data fulfilled selection criteria and were extracted)			NA	16	16	NA
	total:			NA	32a	32a	NA
Barennes 2005 (parallel RCT)	I: sublingual treatment: 2.5 g of wet sugar under the tongue	—	156	27	27	27	100	NA
	C: oral treatment: 2.5 g of sugar on the tongue			15	15	15	100
	total:			42	42	42	100
Slama 1990 (parallel RCT)	I: combined oral + buccal treatment: 15 g of glucose supplied in the form of 40 g of a 40% dextrose gel	—	41	6	6	6	100	NA
	C: oral treatment: 15 g of glucose in tablet form to be chewed and swallowed without water, or 15 g of glucose swallowed with water			12	12	12	100
	total:			18	18	18	100
Gunning 1978 (cross‐over non‐RCT)	I: buccal treatment: 15 g of instant glucose, placed between the teeth and the cheek of each participant; participants were encouraged not to swallow	—	7 participants with full cross‐over	NA	7	7	NA	NA
	C: oral treatment: 15 g doses of instant glucose, to be swallowed by the participants			NA	7	7	NA
	total:			NA	14a	14a	NA
Grand total	All interventions			RCTs: 60 non‐RCTs: 46a Total number of participants: 83

— denotes not reported

^aFor cross‐over studies participants are analysed both for intervention and comparator groups

C: comparator; I: intervention; NA: not applicable; RCT: randomised controlled trial.