Hmm - any time we eat we have insulin spikes - not sure what you mean about extra insulin pertaining especially to homemade whey shakes/smoothies. However: there is a HUGE difference between undenatured whey (which I use - basically dried unprocessed whey from grassfed happy cow milk) and the highly processed yucky whey protein isolate made in labs and which is nasty for various reasons. They have quite different impacts, despite both delivering protein. There are past posts in this forum about the nastiness of isolate, etc.
I’m non-IR and not obese - but others who are IR or obese may need to avoid any sweet triggers and may also have dairy intolerance. I just know for me that when I started mixing dry Ginger into my smoothies or taking capsules along with my smoothies as a digestive, it worked wonders. No strange feelins’, and lots of delicious coolness - Ginger really helps digestive enzymes and reduces cortisol (and also lowers insulin spiking in western industrial medicine rat studies - though Ginger’s been a super medicine in the east for thousands of years, etc.) I enjoy smoothies 3-4 times few times a week - while having great recomposition progress over the last year of keto. I started out having smoothies as my first ‘solid’ meal of the day, an hour or two after weight lifting, because I simply was too tired to cook! Esp handy in hot weather - my smoothies are my first official meal of the day a few hours after fatty coffee.
Smoothies are a key component of the “Losing the Middle Age Middle” eating plan of the LCHF/Keto physicians Mary Dan Eades MD and Michael Eades MD… having to do with giving the digestion a break and facilitating cortisol reduction. Lots of smoothie recipes in their book.
Could it be your shakes are lacking something or having too much of something? Mine are typically 20-25grams of protein from undenatured whey, additional incomplete protein from a scoop of collagen peptides - plus 1/2 cup berries or a scoop of powdered pomegranate or rasp (if I don’t have them on hand, I instead take a Vit. C, as collagen uptake requires C), 1 tblsp cocoa powder, 5-6 teaspoons erythritol (it doesn’t get metabolized by the body, and I don’t count erythritol carbs) possibly with a drop of stevia, 1/4 - 1/2 teaspoon Maca powder (for a malt), cold water from the fridge and 4-6 ice cubes, Pinch of sea salt to bring it all together, taken with some Ginger capsules on the side. In a huge stein. 
I learned about Maca just a month ago - it’s amazing how just a tiny amount of it in a smoothie makes it malty, which I love. One of these high summer days am gonna experiment with a simpler smoothie along the lines of an old fashioned vanilla malt.
Until I was 100% fat-adapted (which for me was around month 6 keto) I also added 1 tablespoon of extra fat in the form of coconut oil or avocado oil - now I just tend to go without the extra fat so that my body can draw upon my own fat stores on my belly 
Have also been experimenting with Olive Nation’s natural extracts - banana as well as berry. They combine well with erythritol, but horribly with stevia for some reason (brings out the stevia metallic taste).
@Deary75 depends on the shake/smoothie - as in, the actual ingredients. Undenatured whey liquid meals can be really great for lightening the digestive load and keeping the kitchen much cooler in summer! Plus, I just love me a frosty mug ;). In winter though, I’ll often create a hot mug of fatty collagen peptide broth + sea salt or a Kallo stock cube + some fat for my first official insulin spiking meal of the day - which is toasty to sip but likewise quick in the kitchen. Both summer and winter, I take Ginger capsules with whatever I’m sipping.
