Almost everytime I measure the blood glucose levels in both right and left hands there's always a difference of 10-20mg/dL. When I first noticed this, I tried using on different individuals, but for everyone the right and left hands had a minimum of difference of 10mg/dL. Using a glucometer of a different company still gave the same results of differences in both hands.

So why is there is a difference between right and left hand blood glucose values?

I couldn't find any satisfactory reason on the net. Also if there is this significant difference then with which value should we go with? The lower value or the higher value?

Not only me but a lot of people has found this difference. When I searched the net this question is quite common. If any of you has a glucometer if you may experiment and let me know the results. I also talked to some doctors. They agreed to have this difference but couldn't give me a possible reason for this.

  • Maybe the accuracy of the glucometer is just about 10mg/dL? Values are also dependent on technique, if you squeeze the finger for collecting the blood (as an example), the value can be up to 50mg/dL higher.
    – Narusan
    Jun 8, 2020 at 8:47
  • @Narusan I have tried this with several models of glucometer. Plus I have tried to keep the technique similar in both hands.
    – Ojasvi
    Jun 8, 2020 at 12:43
  • Have you tried serial measurements from the same hand? Do you not see the same variation when you do that?
    – Carey Gregory
    Jun 8, 2020 at 14:48
  • @Carey yes I have tried. However the variation is maximum of 7-10 mg/dL. I even tried different fingers of the same hand, i.e first from the third finger first and then fourth finger. However the differences are slight. Not as significant as seen between right and left hands.
    – Ojasvi
    Jun 8, 2020 at 15:20
  • 1
    Are the glucose levels always lower in the dominant hand? Jun 8, 2020 at 21:40

1 Answer 1


I'm not aware that capillary blood glucose levels have been systematically examined but interstitial fluid glucose levels in one study using a Freestyle Libre Pro appeared to show higher levels in the dominant arm whereas one might expect the increased muscle bulk on the dominant arm to extract more glucose. Another possibility is that if there is increased muscle bulk in the dominant arm, and insulin resistance relates to muscle bulk, then levels of glucose would then be expected to be higher in the dominant arm.

One test would be to see if there is any difference between the two legs and there should not be.

A total of 1920 time matched left-arm and right-arm pairs were analyzed. The right arm was greater than the left arm 96.0% of the time (Figure 1). The average glucose readings for the right and left arms were 96 ± 16 mg/dL (range 68-186) and 88 ± 15 mg/dL (range 57-174), respectively (P ≤ .001). The minimum and maximum changes in the right arm relative to the left arm were −11 and 41 mg/dL respectively. In the right arm, 2.19% of the values were outside the 70-140 mg/dL range compared to 4.58% in the left arm (P ≤ .001). In 14.1% of cases, the right arm was greater than the left arm by 15% or more. There is no correlation between the magnitude of intra-arm differences and glucose levels (R2 < .09).

Differences in Glucose Levels Between Left and Right Arm https://europepmc.org/article/pmc/pmc6610604

  • I don't know about the periphery, but in the brain at least, blood flow always overcompensates for need (and this is the principle of fMRI, where increased metabolism causes increased rather than decreased oxygenation, at least after a fraction of a second). It wouldn't surprise me if overall blood flow was higher in a dominant arm, but glucose extraction is fairly similar in both arms when not exercising the dominant arm.
    – Bryan Krause
    Jun 9, 2020 at 0:30
  • Possibly though I would have thought that homeostasis based on oxygen demand would drive the blood flow. Jun 9, 2020 at 3:52

Not the answer you're looking for? Browse other questions tagged or ask your own question.