Common Mistakes When Checking Blood Sugar

A blood sugar reading is only as good as the way it was taken, and a handful of small errors account for most of the readings that make no sense.

The common ones

• Unwashed hands. The single biggest cause of a falsely high reading. Fruit juice, sweet chai or even handling food leaves enough glucose on a fingertip to distort the result badly. Wash with plain water and dry properly — an alcohol swab left wet also skews it.
• Squeezing the finger hard. This dilutes the sample with tissue fluid and reads low. Let the drop form.
• Strips past their date, or badly stored. Heat and humidity ruin strips, which matters in an Indian summer. Keep the vial closed and out of the bathroom.
• Testing at inconsistent times, so no two readings can be compared.
• Testing too late after a meal. One to two hours from the first bite; at three hours the peak has usually passed.
• Always using the same finger, which becomes sore and stops giving a clean drop. Rotate, and use the sides rather than the pad.

When a reading looks wrong, repeat it with washed hands and a fresh strip before acting on it. A surprising number of alarming numbers do not survive a second test.

There is a step-by-step guide to using a glucometer properly in the Knowledge Base.