Table A2.

Small-study effects in the relationship between sleep characteristics and glycemic control.

Sleep variables	Analysis	Sleep measures	No. of studies	Type of subjects	Egger test
Sleep stages	MD in percentage of sleep stages between optimal and suboptimal glycemic controls	PSG, wireless sleep monitor	5	Adults	β = −2.45, SE = 2.70, p = 0.432 β = 2.72, SE = 2.33 , p = 0.328
Sleep duration	MD in HbA1c between longer and shorter sleep durations	PSG, wireless sleep monitor or actigraphy	6	Adults	β = 0.53, SE = 0.59, p = 0.392
		Questionnaire	4	Adults	β = 0.74, SE = 1.42, p = 0.655
		Questionnaire	3	Adolescents/children	β = −3.22, SE = 5.33, p = 0.654
	MD in sleep duration between optimal and suboptimal glycemic control	PSG, wireless sleep monitor or actigraphy	6	Adults	β = −2.32, SE = 0.83, p = 0.048
		Questionnaire	4	Adults	β = −0.70, SE = 0.57, p = 0.348
		Questionnaire	4	Adolescents/children	β = 11.674, SE = 4.605, p = 0.239
Sleep quality	MD in HbA1c levels between good and poor sleep quality	PSG or actigraphy	4	Adults	β = −0.43, SE = 0.19, p = 0.149
		Questionnaire	3	Adults	β = −1.03, SE = 0.864, p = 0.445
	MD in sleep quality between optimal and suboptimal glycemic controls	PSG or actigraphy	5	Adults	β = −1.28, SE = 0.27, p = 0.018
OSA	MD in HbA1c levels between OSA and non-OSA	PSG or oximetry	4	Adults	β = −1.38, SE = 1.56, p = 0.468
	MD in HbA1c levels between moderate-severe OSA and non-OSA	PSG	3	Adults	β = 0.59, SE = 1.75, p = 0.791
	MD in AHI between optimal and suboptimal glycemic controls	PSG	4	Adults	β = −1.32, SE = 1.03, p = 0.330

Abbreviations: AHI, apnea−hypopnea index; MD, mean difference; OSA, obstructive sleep apnea; PSG, polysomnography.