Serum Surfactant Protein D as a Biomarker for Measuring Lung Involvement in Obese Patients With Type 2 Diabetes

J Clin Endocrinol Metab. 2017 Nov 1;102(11):4109-4116. doi: 10.1210/jc.2017-00913.


Context: Lung impairment is a new target for late diabetic complications. Biomarkers that could help identify patients requiring functional respiratory tests have not been reported.

Objective: Our aim was to examine whether serum surfactant protein D (SP-D) and A (SP-A) could be useful biomarkers of lung damage in obese patients with type 2 diabetes (T2D) without known lung disease.

Design and setting: A case-control study conducted in an ambulatory obesity unit.

Patients: Forty-nine obese patients with T2D and 98 subjects without diabetes matched by age, sex, body mass index, and waist circumference were included.

Interventions: Serum SP-D and SP-A levels were measured using enzyme-linked immunosorbent assay. Forced spirometry and static pulmonary volume were assessed.

Results: Patients with T2D exhibited higher serum SP-D concentrations than control subjects (P = 0.006). No differences in serum SP-A concentrations were observed. There was an inverse association between forced expiratory volume in 1 second (FEV1) and serum SP-D (r = -0.265; P = 0.029), as well as a significant positive relationship between SP-D concentration and residual volume (r = 0.293; P = 0.043). From receiver operating characteristic analysis, the best SP-D cutoff to identify a FEV1 <80% of predicted was 132.3 ng/mL (area under the curve, 0.725; sensitivity, 77.7%; specificity, 69.4%). Stepwise multivariate regression analysis showed that serum SP-D concentration ≥132.3 ng/mL was independently associated with a FEV1 <80% of predicted (R2 = 0.406). Only the existence of T2D contributed independently to serum SD-P variance among all subjects (R2 = 0.138).

Conclusions: Serum SP-D concentration can be a useful biomarker for detecting lung impairment in obese patients with T2D.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biomarkers / blood*
  • Case-Control Studies
  • Diabetes Complications / blood
  • Diabetes Complications / diagnosis
  • Diabetes Mellitus, Type 2 / blood*
  • Diabetes Mellitus, Type 2 / complications
  • Female
  • Humans
  • Lung / physiopathology
  • Lung Diseases / blood
  • Lung Diseases / complications
  • Lung Diseases / diagnosis*
  • Male
  • Middle Aged
  • Obesity / blood*
  • Obesity / complications
  • Pulmonary Surfactant-Associated Protein D / blood*
  • Respiratory Function Tests
  • Sensitivity and Specificity
  • Spirometry


  • Biomarkers
  • Pulmonary Surfactant-Associated Protein D