Among these five studies, one study was prospective in design, but all studies provided identical results: increased HDL‐c was a protective factor and it delayed the glycaemic deterioration, oral antidiabetic drug initiation or insulin initiation.40, 41, 49, 50, 78 In addition, the ratio between HDL‐c/apolipoprotein A‐I and M‐HDL‐subclasses also delayed diabetes progression.40, 59. Here, INS is linked to diabetes mellitus.