Acute-Phase Serum Amyloid A Protein and Its Implication in the Development of Type 2 Diabetes in the KORA S4/F4 Study

OBJECTIVE-We sought to investigate whether elevated levels of acute-phase serum amyloid A (A-SAA) protein precede the onset of type 2 diabetes independently of other risk factors, including parameters of glucose metabolism. RESEARCH DESIGN AND METHODS-Within the population-based Cooperative Health Research in the Region of Augsburg (KORA) S4 study, we measured A-SAA concentrations in 836 initially nondiabetic subjects (55-74 years of age) without clinically overt inflammation who participated in a 7-year follow-up examination including an oral glucose tolerance test. RESULTS-A-SAA concentrations were significantly associated with incident type 2 diabetes (odds ratio ION for a one-SD increase of A-SAA adjusted for age and sex = 1.28 [95% CI 1.08- 1.53], P = 0.005), particularly in younger subjects (P value for interaction = 0.047). The association attenuated when adjusting for parameters of glucose metabolism (fasting glucose, fasting insulin, HbA1c, and 2-h glucose; OR 1.16 [0.95-1.42], P = 0.15). Similar analyses for high-sensitive C-reactive protein (hs-CRP) yielded the following ORs: 1.39 (1.10-1.68, P = 0.0006) and 1.13 (0.88-1.45, P = 0.34), respectively. In contrast, A-SAA concentrations were significantly associated with 2-h glucose levels at follow-up even after adjustment for parameters of glucose metabolism (P = 0.008, n = 803). CONCLUSIONS-Our findings indicate similarly strong prospective associations with type 2 diabetes for A-SAA and hs-CRP and suggest a potential causal link via postchallenge hyperglycemia.