Circulating C3 and glucose metabolism abnormalities in patients with OSAHS

Obstructive sleep apnea hypopnea syndrome (OSAHS) is a common breathing disorder during sleep characterized by multiple disease roots, including disorders of complement and glycometabolism. And the main purpose of the present study is to make clear the effect of complement C3 on glucose metabolism abnormalities in patients with OSAHS.

This was a cross-sectional study. Two hundred six patients, mean age 44.58 ± 11.84 years and 26 female patients (26/206), had been suspected with OSAHS and underwent overnight polysomnography. The assessment of complement levels included complement 3 (C3), complement 4 (C4), and serum total complement (TC). The measured indicators of glucose metabolism were fasting blood glucose (FPG), fasting insulin (FINS), and 75 g oral glucose tolerance test-derived glucose. A multivariate linear regression was used to determine relevant factors with 2-h postprandial blood glucose (2hPG) and C3.

The patients were classified according to apnea-hypopnea index (AHI) into four groups: simple snore (n = 21), mild OSAHS (n = 43), moderate OSAHS (n = 35), and severe OSAHS (n = 107). The level of C3 in the severe OSAHS was higher than other groups (simple snore: 1.16 ± 0.18 g/L VS 1.00 ± 0.18 g/L, p < 0.001; mild OSAHS: 1.16 ± 0.18 g/L VS 1.04 ± 0.17 g/L, p < 0.001; moderate OSAHS: 1.16 ± 0.18 g/L VS 1.06 ± 0.14 g/L, p = 0.003) and no-severe OSAHS group (1.16 ± 0.18 g/L VS 1.04 ± 0.16 g/L, p < 0.001). And C3 was associated with AHI, average pulse oxygen saturation (A-spo2), homeostasis model assessment-insulin resistance (HOMA-IR), 2hPG, age, sleep stage (I + II)/TST, and sleep stage (III)/TST, respectively. HOMA-IR was correlated to AHI after adjustment with age and BMI. OSAHS was an independent risk of C3 regardless of obesity and sleep parameters (p = 0.002). After adjustment with neck circumference (NC), BMI, AHI, sleep stage (I + II)/TST, and sleep stage (III)/TST,C3 level was associated with 2hPG (p < 0.001).

A high level in C3 is correlated with the occurrence of OSAHS and C3 alterations in OSAHS patients seem to contribute to disorders of glucose metabolism. And targeting OSAHS to improve glucose metabolism and immune function could be useful.