Analysis of the Effect of the Lowest SpO2 on Nocturnal Blood Glucose Fluctuation in Type 2 Diabetes Measured by WatchPAT and Continuous Glucose Monitoring
Authors: SHINODA MINORI , YAMAKAWA TADASHI , SAKAMOTO RIKA , SUZUKI JUN , TAKAHASHI KENICHIRO , TERAUCHI YASUO 
Published: June 2018

Although sleep apnea syndrome reportedly increases nocturnal blood glucose (BG) variability, few studies have assessed the effect of the lowest oxygen saturation (SpO2) during sleep on short-term BG levels. Thus, this prospective study of BG fluctuations while sleeping was conducted on subjects fitted with a continuous glucose monitoring (CGM) device and a WatchPAT®, allowing simple evaluation of sleep-disordered breathing. Ninety-two patients with type 2 diabetes were fitted with the two devices overnight in the hospital when the glycemia was stable (∼7-10 days) in order to avoid the effects of hyperglycemia. The subjects were aged at least 18 years.
Results: The subjects were categorized according to their lowest SpO2 by WatchPAT (SpO2 ≥90%, 85%≤ and &lt;90%, or &lt;85%). As SpO2 decreased, elevated body mass index (BMI) (20.3±3.3 vs. 25.3±3.9 vs. 28.7±5.8 kg/m2, mean±standard deviation (SD); p&lt;0.001) and increased endogenous insulin secretion (1.3±0.7 vs. 2.2±1.1 vs. 2.5±1.3 ng/mL; p=0.002) were observed. Using BG level at the time of the lowest SpO2 as baseline, comparison of the differences in BG values every 30 minutes for 3 hours showed significantly worsened BG levels for SpO2 &lt;90% (30 min-baseline 4.4±3.2 vs. 180 min-baseline 18.7±22.4 mg/dL; p&lt;0.001). In addition, in the 30 minutes after the lowest SpO2, the BG level was elevated in the SpO2 &lt;85% group compared to those in the other groups (SpO2 ≤90% 4.1±3.2 vs. 85%≤ SpO2 &lt;90% 4.4±3.2 vs. SpO2 &lt;85% 7.8±6.9 mg/dL; p=0.03). In contrast, no significant differences were noted in mean BG, mean amplitude of glycemic excursions (MAGE), SD, or coefficient of variation (CV) among the three groups from 00:00 to 06:00.
Conclusions: Even without differences in nocturnal fluctuations of BG levels, because of treatment, hypoxemia during sleep causes short-term worsening of glycemia. Moreover, the greater the degree of hypoxemia, the earlier the worsening is likely.

Disclosure
M. Shinoda: None. T. Yamakawa: None. R. Sakamoto: None. J. Suzuki: None. K. Takahashi: None. Y. Terauchi: Research Support; Self; MSD K.K.. Speaker's Bureau; Self; MSD K.K.. Advisory Panel; Self; MSD K.K.. Research Support; Self; Ono Pharmaceutical Co., Ltd.. Speaker's Bureau; Self; Ono Pharmaceutical Co., Ltd.. Research Support; Self; Novartis Pharma K.K., Boehringer Ingelheim GmbH. Speaker's Bureau; Self; Boehringer Ingelheim GmbH. Advisory Panel; Self; Boehringer Ingelheim GmbH. Research Support; Self; Mitsubishi Tanabe Pharma Corporation. Speaker's Bureau; Self; Mitsubishi Tanabe Pharma Corporation. Advisory Panel; Self; Mitsubishi Tanabe Pharma Corporation. Research Support; Self; Daiichi Sankyo Company, Limited. Speaker's Bureau; Self; Daiichi Sankyo Company, Limited. Advisory Panel; Self; Daiichi Sankyo Company, Limited. Research Support; Self; Sanwa Kagaku Kenkyusho Co., Ltd.. Speaker's Bureau; Self; Sanwa Kagaku Kenkyusho Co., Ltd.. Research Support; Self; Novo Nordisk Inc.. Speaker's Bureau; Self; Novo Nordisk Inc.. Advisory Panel; Self; Novo Nordisk Inc.. Research Support; Self; Eli Lilly and Company. Speaker's Bureau; Self; Eli Lilly and Company. Advisory Panel; Self; Eli Lilly and Company. Research Support; Self; Sanofi. Speaker's Bureau; Self; Sanofi. Advisory Panel; Self; Sanofi. Research Support; Self; Sumitomo Dainippon Pharma Co., Ltd.. Speaker's Bureau; Self; Sumitomo Dainippon Pharma Co., Ltd.. Research Support; Self; Shionogi & Co., Ltd.. Speaker's Bureau; Self; Shionogi & Co., Ltd., Bayer Yakuhin, Ltd., Astellas Pharma US, Inc., AstraZeneca. Advisory Panel; Self; AstraZeneca, Teijin Pharma Limited.