I'm also a insulin dependant diabetic, I maintain a 5.4 a1c, which is incredible, am very active in the diabetic community knowing many that Vape w no problems. I chain Vape for the most part as well... what eliquid is he using ? Is he seeing a endo? Mine is quite prominent and is thrilled w my vaping and blood glucose levels. When did he start vaping? If I can help I'd be glad too. Perhaps the liquid your using has alcohol in it, sugars or simply the detox is causing his sugars to fluctuate?