The Blog

Does Checking My Blood Sugar Really Matter?

Written by Maria Curcio, MS, RD,CDE
Fit4D Nutrition Coach

A study recently came out titled “Self-monitoring of blood glucose in patients with type 2 diabetes mellitus who are not using insulin”. It said that if you are not on insulin, that regularly checking your blood sugars does not make a significant difference in your diabetes management.  As a CDE, my initial reaction was shock, and that’s why you’re reading this.  So before you throw away your meter let’s consider a few facts.

Without going into detail about clinical research, it’s difficult to control cause and effect, such as checking blood glucose (BG) when the participants have the liberty to check or not to check their BGs. It’s also difficult to know if the outcome, in this case lowering A1c, is due to differences in how study participants in both groups followed instructions such as checking BG, eating healthier, exercising and adherence to taking medications.   So that’s it for the research jargon!

Why do I need to check my blood sugars when I have diabetes?

As health care providers, we are always looking at the evidence – does the outcome of an action like checking your blood sugars result in enough of a benefit to keep doing it?  It’s unknown whether self-monitoring is effective in lowering A1c if you are taking oral medications. Because that part is unproven, let’s review what we do know. 

  • There is a prediabetes phase to this condition when your BGs are elevated causing damage to your blood vessels before diagnosis.  
  • If your doctor prescribed diabetes medication, then your BG is elevated.  Usually when medication is prescribed, lifestyle changes such as a healthy diet and exercise are recommended, too.
  • The best way to know whether the medication and lifestyle changes are working is SMBG.  It isn’t a good idea to assume the medication is lowering your BGs because that might be happening, but the only way to know if it’s low enough is to check your BG.  Let’s say that you’re eating healthfully, walking more and have been on metformin for 2 months. You’re checking your BG once per day and it’s always above 160 upon awaking which is above the recommended 130.  You speak with your  HCP who increases your dose of medication, and it comes down to the 100 range which is within the target goal. This is actually a true story of how blood glucose monitoring can help people with diabetes who are not taking insulin.
  • There are no early symptoms that high BGs are damaging the blood vessels of the eyes, kidneys and feet until it’s too late.
  • Keeping your BG within target range (ADA recommends fasting between 70 and 130 and  post meal of under 180) significantly decreases the risk of developing diabetes-related complications.  And how would you know if your BG is within the target range? That’s right, by checking your BG!
  • SMBG on a daily basis is useful for adjusting your food choices, exercise and for knowing if have to contact your HCP to adjust your medication between appointments.  I had as a patient a middle-aged woman who had been taking glimeperide for almost 1 year when she started to experience ‘dizzy’ spells several hours after eating.  She was on the lowest dose possible.  When she checked her BG it was in the 60s. This happened on several consecutive days.  After she called her doctor, he took her off the medication.  She’s been diet and exercise-controlled since.
  • You can know your A1c before your next doctor’s visit by comparing your 1 week, 14 day or 30 day average BG reading from your meter using the estimated average glucose chart (eAG). This is a great and reliable way to estimate how well you’re managing your diabetes.  For example, if your 30 day BG average from your meter is 169 mg/dl, using the chart below you know that your A1c is 7.5%. 
A1C% eAG mg/dl A1C% eAG mg/dl
 5 97 8.5 197
5.5 111 9 212
6 126 9.5 226
6.5 140 10 240
7 154 10.5 255
7.5 169 11 269
8 183 11.5 283
  • Feeling is not the best gauge of how high or low your BGs are.  By the time you ‘feel’ your BG is high, it is causing damage.  One patient, whom I knew very well, was speaking with me on the phone and was more irritable than usual.  I asked Mrs. Jones (not her real name), “Are you feeling okay?  Have you checked your BG today? You don’t sound like yourself.”  She was so busy that she’d completely forgotten.  While I was on the phone with her she checked—it was 270.
  • By the time you feel your BG is low, it might be declining too quickly for you to intervene. Unfortunately, I have had my share of patients who take their morning glyburide, eat breakfast and in the middle of running errands, develop hypoglycemia  (low blood sugar) that would have been picked up if the BG had been checked that morning.  This can be a dangerous situation that can be prevented with a quick BG check.
  • Class of medications called scretagogues lower BGs by stimulating insulin release, and can
    cause hypoglycemia.  These medications include glyburide,  glimiperide, repaglinide and nateglinide.  Exenatide is a different class of medication that also has the potential to cause hypoglycemia. 
  • And of course, if you’re taking either short or long-acting insulin you want to check your BGs daily as your HCP recommends.

A little number reaps huge rewards

I have had the pleasure of counseling young and older folks alike who have diabetes.  None of them have ever said that they enjoy sticking their finger or forearm or other chosen site.  But no one has ever said that knowing their BG wasn’t useful in helping them either lower or increase their carbs, knowing if a little snack is needed before they take that walk or splitting that metformin dose to help lower their after dinner BGs.  However, I have had several folks ask me why they aren’t checking their BGs at home instead of waiting the 3 or 6 months before their doctor’s appointment.   The ‘worse’ thing that can happen is you’ve stuck your finger.  Now compare that to the benefit you get of knowing that your BG is on target. 

How has checking your blood glucose helped you? Share your experience with us in the comments section!

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