Gluc checks after drinking

I'm a nursing student and came across this situation and just wanting to ask for some opinions.

I had a patient who is Type 2 DM and is normally taking Metformin (but was d/c while in hospital due to issues with the kidneys). The pt doesn't take insulin at home but was on sliding scale while hospitalized.

Pt just drank about 175ml orange juice 10mins prior to me checking CBG, the result indicated about 16mmol/L. This required 6units of insulin. My understanding is SS is based on a "fasting" CBG but since the pt just drank OJ, blood sugars will rise rapidly and so the value to base SS is not accurate. My fear was if 6 units were given, there'd be a high risk of hypoglycemia b/c pt is Type 2 and indication of Metformin is that pt is still producing insulin but cannot effectively take it up into cells.

My choice was to wait about 15min and recheck blood sugars and use that value to base insulin requirement. I understand that the sugars will still be on the higher end but then there'd be less risk of overdose of insulin. Any opinions? Would you suggest to use the initial value instead of waiting 15mins?

Thanks :)