Obstructive sleep apnea and insulin resistance in children with obesity

Abstract

Study objectives: Because existing data investigating obstructive sleep apnea (OSA) and insulin resistance (IR) are inconsistent, we examine OSA and IR in a pediatric obesity clinic.

Methods: Children (2-18 years) in the obesity clinic (2013-2017) undergoing polysomnography (PSG), anthropometric measurements, and fasting laboratory tests were included. Linear regression assessed OSA defined by the obstructive apnea-hypopnea index (oAHI) with the homeostatic model assessment of insulin resistance (HOMA-IR). Secondary aims assessed oxygen desaturation index (ODI) and age interactions with HOMA-IR. Logistic regression models and receiver operating characteristic analysis were performed to investigate optimal oAHI and ODI cutoffs relative to HOMA-IR ≥ 3.

Results: Eighty children were included (mean age, 11.4 ± 4.0 years; 56% female; 46% Caucasian; median body mass index [BMI], 34.6 kg/m² [interquartile ratio, 29.9-40.1], median BMI z-score, 2.5 [interquartile ratio, 2.3-2.8); 46% with oAHI ≥ 5 events/h. HOMA-IR was higher in the OSA group (oAHI ≥ 5 events/h): 5 vs 3.8 (P = .034). After adjustment for sex, race, and BMI z-score, oAHI ≥ 5 events/h retained significance with HOMA-IR (P = .041). HOMA-IR increased in older children (age ≥ 12 years) when adjusting for waist circumference z-score and waist-height ratio (statistical interaction, P = .020 and .034, respectively). Receiver operating characteristic showed optimal cut points of oAHI and ODI for predicting significant IR 4.9 (area under the curve, 0.70; 95% confidence interval, 0.57-0.83; sensitivity, 0.76; specificity, 0.66) and 4.6 (area under the curve, 0.68; 95% confidence interval, 0.55-0.80; sensitivity, 0.70; specificity, 0.67), respectively.

Conclusions: In a clinic-based pediatric cohort with obesity, OSA is associated with increased IR even after adjusting for confounders including obesity defined by the BMI z-score. Age ≥ 12 years was associated with AHI relative to IR after adjustment for waist circumference z-score and waist-height ratio. Significant IR could be discriminated by oAHI ≥ 4.9 with moderate sensitivity/specificity. Future studies are needed to verify these findings.

Keywords: children; insulin resistance; obesity; obstructive sleep apnea.

Figure 1. Scattered plots showing the relationship of HOMA-IR and oAHI along with interactions of age and BMI z-score.

The relationship between HOMA-IR and oAHI had no significant difference (P = .41) among age groups when using the interaction of BMI z-score. BMI = body mass index, HOMA-IR = homeostatic model assessment of insulin resistance, oAHI = obstructive apnea-hypopnea index.

Figure 2. Scatter plots showing the relationship of HOMA-IR and oAHI along with interactions of age and waist circumference z-score.

The relationship between HOMA-IR and ODI was significant (P = .029), when factoring waist circumference z-score, where HOMA-IR increased in the older group but decreased in the younger group when oAHI increased. BMI = body mass index, HOMA-IR = homeostatic model assessment of insulin resistance, oAHI = obstructive apnea-hypopnea index, ODI = oxygen desaturation index.

Figure 3. Receiver operating characteristic curve (ROC) of sleep indices on HOMA-IR ≥ 3.

Top: ROC of oAHI on HOMA-IR ≥ 3. The association of oAHI and HOMA-IR ≥ 3 was significant at P = .028. The oAHI cutoff value was 4.9 (sensitivity, 0.76; specificity, 0.66) and AUC was 0.70 (95% confidence interval, 0.57–0.83). Bottom: The association of ODI and HOMA-IR ≥ 3 was not significant (P = .11). The ODI cutoff value was 4.6 (sensitivity, 0.70; specificity, 0.67, and AUC was 0.68 (95% confidence interval, 0.55–0.80). AUC = area under the receiver operating characteristic curve, HOMA-IR = homeostatic model assessment of insulin resistance, oAHI = obstructive apnea-hypopnea index, ODI = oxygen desaturation index.