After a recent blood test that showed elevated fasting glucose (110mg/dl) and elevated triglycerides (~335mg/Dl), I got myself an Accu-check glucose tester and started regular testing to try to figure out where I'm at in terms of insulin resistance etc.

Several times now I've had a set of results I don't understand. Today for example, I tested my glucose level right after waking up and I got 106mg/dL. Feeling this was a bit high (my average over the last 7 days is 100) I drank a bit of water (as I hadn't drank any overnight) and re-tested 20mins later. The second test result was 96mg/dL.

Same thing happened three days ago with 108 and 109 after testing twice immediately after waking up, then 97mg/dL 25 mins later (again after having a bit of water as I hadn't drank any during the night).

Which of these results is more relevant/accurate. Is the first one skewed by slight dehydration, or is the second one less relevant because of either the water or the ~20 mins of activity?

For context, I suspect that the elevated glucose and triglycerides stem from both my sedentary lifestyle and daily alcohol use. My diet on the other hand has been quite good and I've generally avoided sugars and high GI carb for almost 10 years now. For the last 10 days I've stopped drinking and am in the gym almost everyday alternating between weight training and ~30 mins on a stationary bike.

Edit 1: As Graham Chiu pointed out, water intake in the morning should not skew my results. Although, I'm unclear whether not drinking enough water on a given night could increase the result the following morning?

The other question is, can there be a ~10+% drop in blood glucose after 20-25 minutes of light activity in the morning? Or should I be chalking this up to coincidence and meter error margins (even though back-to-back results are quite consistent)?


What you may be experiencing is what is commonly referred to as the "dawn phenomenon". This is where blood sugar becomes elevated between 2-8am. This happens when your blood glucose goes low in the evening. The body compensates by releasing stored glucose from the liver. In people without diabetes the body would simply produce more insulin and regulate their blood sugar. In a person with diabetes the insulin is ineffective or insufficient and blood sugar remains high.

One way I had clients treat this is to have a small snack an hour before bed that had about 30g of carb, and 15 g of protein (to slow the rise of blood glucose). This was enough to prevent the overnight low in the middle of the night and rebound high in the morning.

The more accurate gauge of how your blood sugar is doing is taking it first thing in the morning. Hydration can affect blood glucose but not as quickly as you are describing.

Exercise however can drop blood glucose as much as 50 points depending on how high levels were before activity, duration of activity, and intensity.

  • 1
    Welcome to health SE :-). Here reliable references are strongly encouraged because heath is a sensitive matter, and the OP as well as other users need a way to verify the validity of an answer. You can always edit your question to add references. Thanks!
    – Lucky
    Apr 21 '16 at 1:08

There's a bit of error involved in using those meters so the different recordings may be within the manufacturer's published range for that particular model. Whether you have a glass of water or two is not going to materially affect the blood glucose level.

The important thing to note is that diabetes is diagnosed on blood testing and not finger prick testing.

Excessive alcohol consumption is one cause among many of elevated triglycerides.

  • Thanks for pointing that out. I am under a Doctor's supervision, so proper lab blood tests are a part of all this, and my use of the finger prick test is more for spotting trends rather than analysing the specific results. As for the meter itself, I have done back-to-back tests with consistent results (e.g. the above mentioned 108 and 109) so the lower results 20-25 minutes later seem to be a consistent trend (barring coincidence). Your answer about drinking water does answer half of this question though. Thanks again.
    – Andy
    Apr 19 '16 at 11:18
  • Test 20 minutes later with no water. Apr 19 '16 at 11:21

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