Have you just started to take insulin?
Your symptoms could be because your blood sugar is too low, either a hypo or a "false hypo". Non diabetics keep their blood sugars between 4 and 7 : if you take insulin and your blood sugar goes below 4 you can go hypoglycaemic: your brain does not have enough energy in it and you can even pass out if you don't ingest sugar. A false hypo means you feel as though you're hypo but your blood sugar is actually in normal range: this happens when you've been having very high blood sugars and you start to go down to normal levels, it passes once your body has got used to those normal levels.
What are your blood sugars when you get these symptoms? Your medical carer really should have told you about hypos if you're on insulin. If your blood sugar goes to less than 4 then you need to take something sugary immediately. (Glucose tablets are ideal but a sweet (non-diet) drink would do as well, even a biscuit would be better than nothing.)
Please contact your medical practitioner urgently about your symptoms: you may need to adjust your insulin dose.