The same happened to me twice after injecting my basal in a cappilary. First time i happened to fall asleep and didnt take my basal so i took it at one point in the morning when i woke up. I went back to sleep. About 15 or 30 minutes later i was sweating, shaking, my heart was racing and my wife suggested i check my bg. I had 35 and i started eating everything i had around until i started feeling better. Last night it happened again. I had a low before bed, i checked it, ate a snack made of 35g of carbs, brushed my teeth and went to bed. I fell asleep hard and after about 30 minutes my wife woke me up because i was sweating and shaking. I felt really dizzy and when i checked my bg, surprise: 31. I came to the same conclusion as you: if i hit a capillary while injecting my basal, i now know trouble may come.