Among individuals for whom we had access to incident diabetes diagnoses during follow‐up (n = 13,572, n events = 1091, median follow‐up time 5.6 years, total follow‐up time 123,003 person‐years), we found that an increase in mean (log) copeptin (z‐score) corresponding to the seasonal variation (i.e., the difference between peak and nadir) was associated with an increased hazard ratio of diabetes (1.040 [95% CI 1.027; 1.053]). Here, AVP is linked to diabetes mellitus.