(Raw data not deposited/available upon request). Analyzed methylation data from Illumina 450k arrays as data tables that report: 1) sites hypomethylated in Alpha cells, 2) sites hypomethylated in Beta cells, 3) sites hypomethylated in both Alpha and Beta cells, 4) sites overlapping Alpha-specifically expressing promoters which are hypomethylataed in Alpha cells, 5) sites overlapping Alpha-specifically expressing promoters which are hypomethylataed in Beta cells, 6) sites overlapping Alpha-specifically expressing promoters which are hypomethylataed in Alpha and Beta cells, 7) sites overlapping Beta-specifically expressing promoters which are hypomethylataed in Alpha cells, 8) sites overlapping Beta-specifically expressing promoters which are hypomethylated in Beta cells, 9) sites overlapping Beta-specifically expressing promoters which are hypomethylataed in Alpha and Beta cells