I would need more information about your diet, exercise routine, insulin dosage, and glucose readings before giving any suggestions. However, I can say this much for now: don't inject insulin before working out simply because you have had some highs! Your highs could very well be due to surges of epinephrine. Moreover, it is impossible to predict whether you will experience these surges during any given workout, meaning if you inject insulin and do not experience this surge, you will go dangerously low. If you provide detailed information about when you eat your meals, what you eat, when you inject, what your sugars are at what times, and what you do for exercise, how intense, how long, etc, I'd be glad to help.
When you work out your muscles release stored glucose, called glycogen, which makes your blood sugar high if it's not used up as you work out. Hours later, your body replaces those glycogen stores by stealing glucose from your blood, causing a delayed low. It's especially common with anaerobic exercise like weight lifting (hiking would do it for me too).
The good news is that over time of doing the same workout your muscles become more efficient and don't need as much glucose, so exercise doesn't impact blood sugar as much. But exercise will make you more insulin sensitive through the day.
People deal with exercise highs in different ways. Some test halfway through their workout and take a small bolus, based on their blood sugar. Others wait until just after working out or give themselves an hour post workout and test and correct. Your corrections shouldn't be as much as a normal. Then test through the day and reduce insulin. It's often smart to eat a bedtime snack and wake up around 2am the first few days of a new workout to make sure you're not low.
Shari Colberg's "The Diabetic Athlete" book gives specific insulin and food adjustments for different activities. Gary Scheiner has a $30 online exercise class at www.type1university.com that's really good. Both Colberg and Scheiner are exercise physiologists who have type 1.
T1 since 1977 Minimed pump since 2002
I used to do the EXACT same thing. During my exercise I would soar up and then about a half hour after I would drop.
This year my doctors finally helped me figure it out. I'm on an insulin pump so I'm not sure if you can do this but... so about an hour before I work out I drop my basal rate by %50 (I know it seems like a lot) and have the temp basal program run for the duration of my workout. Once I tried this it was amazing when I would test during exercise I would be perfectly normal! and the I didn't drop as much afterward but I do try to eat at least a little something after I workout now to make sure that I don't drop.
So with being off the pump I would talk to your doctor and see if there is an equivalent to what pump user do by lowing their basal rates... sorry I can't give you much information and the injection subject.
For me; before games and practices, my sugar elevates a little bit (170-200) and if it is around that level, I'll eat some protein about an hour out prior to game time. When I do that, my sugar usually stays right around that level during the whole game/practice. Injecting a bolus during or before the game (if blood sugar is a little higher) doesn't ever have an effect on my blood sugar as far as lowering it. I see those effects that night after the game.
I'm not on the pump, I use the novolog flexpens and lantus; so for me I get my sugar to about 170, eat some protein, and then throughout the competition I drink a lot of water to try and keep the sugar at that level. Before I go to bed after games and even practice days (everyday for football) i eat some peanut butter (protein to keep sugar leveled out) and some milk and do little to no bolus depending on blood sugar. For my lantus during the season, it is lower than what it is outside of season and I actually do half of my lantus when I wake up, and half of it before bed.
That has all worked for me. Hopefully for you too.