Surfactant protein d, a marker of lung innate immunity, is positively associated with insulin sensitivity

Diabetes Care. 2010 Apr;33(4):847-53. doi: 10.2337/dc09-0542. Epub 2010 Jan 19.


Objective: Impaired lung function and innate immunity have both attracted growing interest as a potentially novel risk factor for glucose intolerance, insulin resistance, and type 2 diabetes. We aimed to evaluate whether surfactant protein D (SP-D), a lung-derived innate immune protein, was behind these associations.

Research design and methods: Serum SP-D was evaluated in four different cohorts. The cross-sectional associations between SP-D and metabolic and inflammatory parameters were evaluated in two cohorts, the cross-sectional relationship with lung function in one cohort, and the longitudinal effects of weight loss on fasting and circadian rhythm of serum SP-D and cortisol concentrations in one prospective cohort.

Results: In the cross-sectional studies, serum SP-D concentration was significantly decreased in subjects with obesity and type 2 diabetes (P = 0.005) and was negatively associated with fasting and postload serum glucose. SP-D was also associated with A1C, serum lipids, insulin sensitivity, inflammatory parameters, and plasma insulinase activity. Smoking subjects with normal glucose tolerance, but not smoking patients with type 2 diabetes, showed significantly higher serum SP-D concentration than nonsmokers. Serum SP-D concentration correlated positively with end-tidal carbon dioxide tension (r = 0.54, P = 0.034). In the longitudinal study, fasting serum SP-D concentration decreased significantly after weight loss (P = 0.02). Moreover, the main components of cortisol and SP-D rhythms became synchronous after weight loss.

Conclusions: These findings suggest that lung innate immunity, as inferred from circulating SP-D concentrations, is at the cross-roads of inflammation, obesity, and insulin resistance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomarkers / blood
  • Blood Glucose / analysis
  • Cross-Sectional Studies
  • Diabetes Mellitus, Type 2 / blood
  • Humans
  • Immunity, Innate / immunology*
  • Insulin
  • Insulin Resistance / physiology*
  • Obesity / blood
  • Pulmonary Surfactant-Associated Protein D / blood*


  • Biomarkers
  • Blood Glucose
  • Insulin
  • Pulmonary Surfactant-Associated Protein D