The effect of cooking upon the blood glucose response to ingested carrots and potatoes

Diabetes Care. 1984 May-Jun;7(3):221-3. doi: 10.2337/diacare.7.3.221.


Ten insulin-dependent diabetic subjects were given the following tests in randomized order: 50 g glucose dissolved in water, 250 g raw and cooked potato (equal to 50 g carbohydrate), 270 g raw and cooked carrot (equal to 25 g carbohydrate), and 4 h of fasting. Blood glucose was measured for 4 h following the tests. The postprandial blood glucose responses after pure glucose and cooked potato were almost similar (90-min values: glucose 8.8 mmol/L, cooked potato 8.0 mmol/L), while the response after raw potato was considerably slower and weaker (90-min value: 3.3 mmol/L). There were no differences between the postprandial blood glucose responses after raw and cooked carrot (90-min values: raw carrot 3.2 mmol/L, cooked carrot 2.8 mmol/L), but the responses were statistically different from blood glucose values during fasting alone (90-min value: 0.8 mmol/L). The study shows that cooking is responsible for the rapid increase in blood glucose after ingestion of cooked potato, while no such phenomenon is seen after cooking of carrots.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Blood Glucose / metabolism*
  • Carbohydrates / pharmacology
  • Cooking*
  • Diabetes Mellitus, Type 1 / blood*
  • Dietary Carbohydrates / pharmacology
  • Fasting
  • Humans
  • Random Allocation
  • Starch / pharmacology
  • Vegetables*


  • Blood Glucose
  • Carbohydrates
  • Dietary Carbohydrates
  • Starch