INS and diabetes mellitus: To find more clues beneath the connection between rs3819316 C > T mutation and diabetes, further analyses for glucose metabolism related indexes were performed in 12,885 non-diabetic individuals, as shown in Fig. 1, the rs3819316 C > T mutation was significantly associated with fasting plasma glucose (FPG), 2 h plasma glucose (2hPG), glucose area under curve (GAUC), homeostasis model assessment of insulin resistance (HOMA-IR), homeostasis model assessment of β cell function (HOMA-β), Stumvoll first phase insulin secretion (STU1), and Stumvoll second phase insulin secretion (STU2).