Serum complement C3 and islet β-cell function in patients with type 2 diabetes: A 4.6-year prospective follow-up study

Serum complement C3 has been shown to contribute to the incidence of type 2 diabetes (T2D), but how serum complement C3 affects islet β-cell function throughout the course of T2D is unclear. This study explored whether serum complement C3 is independently associated with changes in islet β-cell function over time in patients with T2D. Serum complement C3 was measured, and endogenous β-cell function was evaluated by area under the C-peptide curve (AUCcp) during an oral glucose tolerance test (OGTT) in 411 patients with T2D at baseline from 2011 to 2015. Next, 347 of those patients with available data were pooled for a final follow-up analysis from 2014 to 2018. Changes in islet β-cell function at follow-up were evaluated by AUCcp percentage changes (ΔAUCcp%). In addition, other possible clinical risks for diabetes were also examined. The 347 patients included in the analysis had a diabetes duration of 4.84 ± 3.63 years at baseline. Baseline serum complement C3 (baseline C3) levels were positively correlated with baseline natural logarithm of AUCcp (lnAUCcp) (n = 347, r = 0.288, p