Delayed Lows after Exercise


After hitting average BS over 180 and an 8.2 a1c, my doc upped my metformin from 1500mg to 2000mg per day and added 25mg glipizide per day.

On my side, I got serious about my diet and changed from 5 x 1/2 hour cardio workouts per week to 3 x 1/2 hour cardio + 1 hour spinning class + 2 heavy leg lifting workouts (leg press, leg extension, and leg curl) per week.

Two weeks in a row I have experienced extreme lows ( 39 and 49) three hours after spinning. I ate before spinning and immediately after spinning, and the last class I drank an 8oz regular Gatorade during the class.

While I am thrilled that my average BS is now below 120, the bottom line is I want to lower my A1C, not die from a sudden low. I haven't called my doc yet, but I am thinking about taking the glipizide later in the day on spinning days. My worry is my numbers will exceed 200 after spinning without it. Not sure which is worse.

Any suggestions?
Happy Holidays,

There is something that is called Post-Exercise Late onset hypoglycemia (PEL). It is most commonly seen in children after an active day they can have sudden lows and these lows overnight can be very scary. The lows can occur anytime up to even 24 hours after exercise (weightlifting). I've heard claims that is is the body suddenly initiating glucose uptake to replenish depleted glycogen stores. For a while after starting insulin I was experiencing sudden lows about 2 hours after exercise and one incident required 90 g of glucose to restore a normal blood sugar. Eventually I found that bolusing and eating promptly after exercise could suppress the PEL. I hope that helps.

ps. The other thing which may have made the situation worse was the gatorade which may have compounded things by causing reactive hypoglycemia.

Hi Brian

Thank for the reply. Not sure what you mean by the Gatorade making things worse. I thought taking in carbs during spinning would avoid the post-workout low. Can you explain further?

Much appreciated.

We are both T2. Most T2s still have some insulin response. But often it is "sluggish." Classic reactive hypoglycemia is when our body senses a surge of carbs but the insulin response is delayed and we overshoot. I always had it bad if I exercised after a meal. Exercise accelerates your uptake of glucose and the "normal" amount of insulin will be too much.

Unfortunately we are advised by the "experts" to take in carbs during exercise in the belief we need to fuel our workout. I don't know, but between you and me I can look in the mirror and see plenty of "fuel" on my body. I believe you should take in carbs during workout only to sustain a normal blood sugar. After the workout, that is when you should eat and take in some carbs to avoid PEL. Just my opinion, others might have other views.


Thanks again. That makes sense. I’ll have to experiment and talk to my doc about adjustments. Tomorrow is another spinning class, so we shall see…

Take care,

Glipizide works by stimulating the pancreas to dump its insulin store. If you are going low post exercise would be considering skipping the glipizide dose on spinning days as you are already depleting tissue glucose levels with the class and need to restore those levels. Driving extra insulin into your system post spinning will likely make the hypos lower.

This happens to me sometimes. I try to work out before 3pm so I don't go low while I'm asleep. On the nights I have water polo practice at 9, I have half a glass of milk before bed, which seems to prevent those lows for some reason.

Thanks for the reply Leah. I think I figured it out. I ate slightly more for breakfast, took the metformin, and saved the glipizide until after the class. I hit 90 immediately after the class and was at 190 1/2 hour later, but that was as high as it went. I was back down below 120 within two hours of class and haven't been below 90 all day. Still going to talk to the doctor tomorrow to be sure what I am doing is OK though.