The purpose of this study is to better understand how sleep apnea contributes to the development of diabetes.

Substantial evidence indicates that obstructive sleep apnea (OSA) is associated with impaired glucose metabolism, however, metabolic mechanisms underlying this association remain unclear. This mechanistic study will determine systemic and cellular metabolic pathways that contribute to impaired glucose metabolism in obstructive sleep apnea (OSA). Understanding of how obstructive sleep apnea (OSA) affects glucose metabolism may help identify novel targets for risk prediction and/or treatment of metabolic impairments beyond continuous positive airway pressure (CPAP). Obstructive sleep apnea (OSA) patients with prediabetes will be studied under three in-laboratory conditions in a randomized cross-over design: untreated condition (obstructive sleep apnea), treated condition (continuous positive airway pressure), untreated but pharmacologically suppressed lipolysis condition (Niacin). The investigator will perform whole body and cellular assessments under each study condition.

Inclusion Criteria:

• Overweight or obese
• Prediabetic
• Sleep apnea

Exclusion Criteria:

• Diabetic
• Severe hypertension
• Taking medications that can confound assessments
• Any history of known bleeding disorders
• Any underlying disease likely to limit life span or increase risk of intervention
• Currently pregnant, trying to get pregnant or nursing