False high readings when blood sugar is actually low

Has anyone ever suffered from symptoms of low blood sugar like shaking, lightheadedness and dizziness, loss of coordination, racing pulse only to check it with your glucometer to have it show that your blood sugar is actually high?

In other words you are experiencing multiple symptoms that you know are due to crashing blood sugar, but the glucometer indicates that your blood sugar is high.

I'm going to share with you the most terrifying experience of my life and explain how I handled it and why.

First some facts about me: I am a 50 year old male, 5'7" and 150 lbs. I have had type 2 diabetes for 13 years. my last A1c was 7.3. I am on 20 units of levemir once a day and 5-10 mg of Byetta before meals.

Lately I have been on Rapaflo for urinary issues and have seem some unusual highs with my blood sugar.

A few days ago my pre-eating blood sugar reading was 85. I wondered if it was too low for 10mg of Byetta but decided to take that dose because I had been running higher after eating blood sugars lately.

About 1 hr & 45 minutes after eating I began feeling shaky like I normally do when my blood sugar is too low, so I tested it and got a reading of 260. The symptoms did not match the reading. Since I was visiting my father in a nursing home I approached a nurse and explained my situation and asked her to use her machine to check my blood sugar, because I thought my machine must certainly be off. So she checked it with her machine and got a reading of 245. She commented that hers was likely to be right since they calibrate it every day. I used the same spot that she pricked on my finger to get another reading from my machine, and it read 270. The nurse even commented that I was really shaking since I had trouble holding my glucometer steady.

I returned to my father's room confused at what to do. By this time the shaking was worse and I was becoming light headed. At this point I wondered whether my blood sugar was really high, or for some unknown reason related to the Rapaflo or something else, I was getting a false high reading when my blood sugar was actually low. I have had my blood sugar as high as 400 without feeling any ill effects before I discovered it was this high by checking it (at the I got that monster high reading I was on prednisone which dramatically raises blood sugar readings)

Anyway, the choice was to do nothing, to treat with humalog to try to get the reading down, or to conclude that the reading was inaccurate and treat with glucose to get blood sugar up that was actually dropping. I chose to treat with Glucose. Things got worse before they got better, as I seemed to really be crashing worse than I ever had in my life. I got lightheaded to the point that I feared I might pass out, and my mouth and throat completely dried up.

I checked my blood sugar again and it came up as 295 on my meter. I treated with more glucose, but could not swallow the chewed up tablet due to the dryness of my mouth and throat. So I went downstairs and got a citrus drink from my car. I wasn't going to ask the nurse at the nursing home for a soft drink since I doubt that she would give it to me, or believe my story about crashing when the monitors indicated that I had high blood sugar.

After about an hour and a half I felt better, but still had to get a friend to pick me up and drive me home. I did not think that I could drive on my own. I checked my blood sugar about 3 hrs later and it came up as 160. Really, if my blood sugar had indeed been in the 250-300 range it would certainly be higher due to all of the carbs I consumed.

At this point I have no idea what was going on. I discontinued the Rapaflo which seemed to be giving me higher numbers when I was taking it and have an appointment to see my Endocrinologist on Wed.

I called the drug manufacturers of Byetta and Rapaflow and asked if they were aware of any issues with negative interactions of their products. They said that they were not, but pointed out that they did not run clinical trials of every combination of medicine.

I am hoping to get to the bottom of this. One of my greatest fears was that I would pass out or have the paramedics get involved or get taken to an emergency room who would have checked my blood sugar, seen it was high and concluded that was the issue and given me insulin to lower it. If my blood sugar was really low as I suspect from the vast number of symptoms, I fear a shot of insulin would have dropped it even lower and possibly ended my life.

Anyway, I'm Wondering if anyone has experienced anything similar.

Thanks for reading this long post.

I should stress that I am not really sure what is going on, only trying to make sense out of what I experienced and observed.


I do not have high readings very often, but usually have symptoms of them--sweaty, dry mouth, shakiness. I am totally hypo unaware, but I know quickly when my BG is high.

Sometimes if I do not believe a reading. I wash my hands really well and try again. Sometimes it makes a big difference if I have something sugary on my fingers. But I am sure the nurse used alcohol for the fingerstick.

The 160 reading could be from a lot of things: your medications kicked in at the perfect moment, your stress level used a lot of energy and lowered it, you ran around a lot, getting food to correct the low, you could still be making some insulin. That is the beauty of diabetes; things happen.

No answers; just thoughts, but I am glad you were OK.

I find that my symptoms of High and Low are often the same. I get sweaty from both,
I don't get shaky from High ones, only low.
I get a weird stiffness in my jaw from High sugars, but sometimes I get a stiff jaw from very low sugars too.

I never trust my symptoms to correct my sugars. I always check it with a finger stick. Then a second time if I am surprised by it.