INS and type 2 diabetes mellitus: Furthermore, Lane et al. showed that T2D risk was greater among those carriers defined as “early risers” vs. “late risers.” They reasoned that because melatonin inhibits glucose-stimulated insulin secretion ex vivo, it is plausible that a longer duration of melatonin secretion and delayed melatonin offset in the morning hours, in concurrence with an earlier wake time, may lead to melatonin suppressing insulin secretion during times of elevated glucose intake (such as breakfast).