an occasion when the levels of sugar in someone's blood become dangerously low and they feel ill and may eventually become unconscious

I once helped a diabetic out of a hypo by giving him a sugar lump. 有一次，我给了一个糖尿病患者一块糖，帮助他从低血糖状态恢复过来。

She suffered a hypo attack that made her lose consciousness. 她突发低血糖，失去了知觉。

a syringe (= hollow needle) used to inject drugs under somoene's skin. It is short for hypodermic syringe

Used hypos littered the room. 房间里到处乱丢着用过的皮下注射器。