Switching between NPH/Reg insulin and Long-acting+Ultra-short Acting Insulins

Let's say we have a patient on 20 units of Humulin BID normally who is admitted to the hospital.

To convert to long-acting and ultra-short acting units for her hospital stay, know the split, which is 70/30 between NPH/Reg. Making 40 x .7 = 28 units of Long-acting Glargine and 40 x 0.3 = 12 units of Lispro.

Since Glargine is slightly more "effective" than NPH, only use 80% of the 70%, which is about 22 units of Glargine.