While I'm sorry to hear your problem I'm super happy to know I'm not alone!
Yes, I have this same problem. I get highs for 6-8 hours. I had this when I used Silhouette Insert (0.9mm). Now I use Mio infusion sets at 0.3mm. With the Silhouette, I had frequent inflamation at the site and these high BG every time I changed sets. With the Mio, I don't get the irritated site and I don't see this high BG after changing.
My guess? Changing the site causes an inflammation and immune response. The deeper penetrating set caused a more severe reaction. White blood cells and macrophages go to the site and cause the insulin to become inactive or lose adsorption. This would effectively cause less insulin to be delivered.Possibly a different infusion set would help.
Now, I have another question for you... My correction ratio is 1U:50mg/dL over 90. After changing sites with the Silhouette, I would get similar changes... ie. after 2hours my BG was up 100mg/dL. Is this is same for you? Or does it go much much higher than expected? Sorry to answer questions and add questions at the same time.