For type 1's we use the 100 Rule to find the correction factor, to do this you just add up your basal and bolus doses for an average day and divide 100 by that figure, so if someone was on 16 units of basal and 18 units of bolus then that would be a total of 34 units of insulin, so 100/34= 2.94, therefore 1 unit of insulin would bring down bg by 3mmol.
It's a rough guide and doesn't always work and the higher the bg levels the more insulin it takes, just checking and I see that your a type 2 so I would seek advice on this matter as the 100 Rule probably doesn't apply to you.