August 21, 2004
Blood Tests and Insulin Injections
Question from Delhi, India:
Why would a postprandial blood sugar, 70 mg/dl [3.9 mmol/L], be lower than a fasting blood sugar, 87 mg/dl [4.8 mmol/L]? Is this something to be concerned about or require further testing? I am 33 and my father has diabetes. One year ago, I had my blood sugar checked and it was within the normal range.
Answer:
Your sugars are fine. Glucose values may rise in the morning as a result of increased glucose output by the liver overnight. In diabetes, the fasting glucose is disproportionately elevated. The cutoff for diabetes is a fasting glucose through the laboratory (not fingerstick), greater than 126 mg/dl [7 mmol/L] on two occasions. Impaired fasting glucose, greater than 100 mg/dl [5.6 mmol/L] is considered pre-diabetes. I suggest you have a regular follow-up with your physician where these tests can be performed.
JTL
