What is capillary blood sugar used for? How is it done?

Capillary glycemia or capillary glycemic self-monitoring is a method that consists of measuring one’s own blood sugar level (blood sugar) . Concretely, the persons involved take a drop of blood from the capillaries in their fingers (the thinnest vessels of the blood circulation system) and then analyze it using a glucometer . The result is then expressed in grams of sugar per liter of blood (g/L). The great power of this medical device ? Small, light and discreet.  

Capillary glycemia is indicated in diabetes self-control: it allows you to monitor and regulate your blood sugar level as best as possible, sometimes adjusting your physical activity, diet or therapy. This monitoring is therefore recommended by doctors, depending on the type of diabetes and the treatments that may be followed:   

• makes it possible to adjust daily insulin doses for people with type 1 diabetes and those on insulin therapy ;  
• makes it possible to control whether taking certain drugs causes hypoglycemia  ; 
• allows diabetics to measure the effect of a food, sport or physical activity on their blood sugar levels  and adjust their lifestyle accordingly; 
• makes it possible to monitor pregnant women suffering from gestational diabetes . 

Self-monitoring of blood sugar is very simple. To get a sample, all you have to do is:

• a blood glucose meter (glucose meter),  
• Adapted scalpels ( fine needles) that must be disposed of in a specific collector after each capillary blood glucose test  . 
• punching device ( for personal use)  
• and classic strips .  

To raise blood sugar daily: 

1. The glucometer is opened  (attached to the strip) and a scalpel is attached to the piercing device.
2. We pierce the pulp of the finger with the punching tool  , then we massage the fingertips. 
3.  The sample is then placed on the strip inserted into the glucometer .
4. The glucometer thus shows the blood sugar level  almost instantly. 

As mentioned above, a capillary glycemia is accomplished by dipping the finger into the core, usually the index . 

The frequency of blood glucose monitoring depends on the type of diabetes you have (type 1 diabetes, type 2 diabetes, or gestational diabetes) and blood glucose targets set in collaboration with a doctor.

There really isn’t a universal rule, but the Higher Health Authority (HAS) recommends:

• For type 1 diabetes –  four to six tests per day (before each meal and two hours after each meal);
•  For type 2 diabetes –   the frequency depends on the type of diabetes and the treatment:
  – if you are on non-hypoglycemic treatment, it is sufficient to have a blood test every three months.
  – if you are taking sulfonylureas or glinides, capillary blood glucose is measured three times a day (one day a week only): just before breakfast, two hours later, and seven hours later.
  – If you are on insulin therapy, the frequency depends on the number and type of injections.
• For gestational diabetes  – it is recommended to measure your blood sugar four times a day: once on an empty stomach, two hours after breakfast, two hours after lunch and two hours after dinner.

Whatever your situation, it is recommended that you do additional checks:

• before driving for a long time ,
• before and after intense or unexpected physical exertion
• Unusual food or activity situations 
• In case of suspected hypoglycemic disease , 
• in case of infection ,
• et cetera. 

According to the French Diabetes Federation , the “normal” blood sugar level on an empty stomach should be between 0.70 g/L and 1.1 g/L blood. It should fluctuate between 1.30 and 1.60 g/L in the postprandial period (up to 2 hours after starting the meal). 

When the ratio falls below 0.5 g, hypoglycemia can be suspected if it is associated with discomfort . 

• In the case of type 1 diabetes:  glycemic targets are set at 70 to 120 mg/dl before meals and < 160 mg/dl after meals.
• In the case of type 2 diabetes:  glycemic targets are set at 70 to 120 mg/dl before meals and 180 mg/dl after meals. 
• In the case of gestational diabetes:  glycemic targets are set at less than 0.95 g/l before meals and less than 1.20 g/l after meals.

Very high capillary blood sugar means the glucose level in the blood is too high. It can occur even when diabetes is balanced:  we are talking about hyperglycemia  (blood sugar level is greater than or equal to 1.10 g/liter on an empty stomach). A few reasons can explain very high capillary glycemia: 

• forgetting the insulin injection
• errors in insulin dosage , 
• irregular drug intake 
• presence of infection ,  
• taking drugs that raise blood sugar,
• stress is important 
• et cetera. 

Note: If the value is much higher than it should be, it is important to go to your doctor or the emergency room.

As the name suggests, very low capillary blood sugar corresponds to an insufficient blood sugar level (less than or equal to 0.7 g/l) . This is called hypoglycemia . This mainly concerns patients treated with insulin or sulfonylureas.   

It can be manifested by sweating, tremors, tremors, palpitations, headaches, visual disturbances including blurred vision, extreme tiredness , drowsiness, feelings of weakness, anxiety, and mood disturbances (sadness, aggression, or euphoria) . And it could be related to:   

• a food intake that is very low in carbohydrates,
• a suppressed or shifted meal ,  
• Excessive sustained physical exertion  without prescribed adjustments in therapy or food compensation . 
• alcohol consumption on an empty stomach,
• diarrhea or vomiting , 
• stress or a strong emotion (even though they often cause hyperglycemia instead).  
• a drug interaction .