Professor Martin Wiseman, Medical and Scientific Advisor for World Cancer Research Fund, gives his top five tips on How To Maintain Healthy Blood Sugar Levels: http://www.medicalnewstoday.com/articles/67006.php
2. Eat fat/protein with sugary foods. Helps blunt the effect. [1]
3. Don't eat too many carbs. Even the AHA recommends below 60% because of other negatives. [2]
4. Eat the right carb sources. Starchy tubers are best: potatoes, yam/sweet potatoes, cassava and rice. And fruits like bananas, plantains and grapefruit.
5. Eat high GI foods unless your blood sugar is chronically elevated. The body likes glucose, particularly the brain. If your active and sensitive, you'll quickly use it for energy. When you're insensitive you need to cut back.
[1] Protein/Fat/Fiber and Glucose Sensitivity: http://www.ncbi.nlm.nih.gov/pubmed/16988118?dopt=Abstract
[2] AHA Recommneds Less that 60% carbs a day: Search "carbs": http://www.americanheart.org/presenter.jhtml?identifier=180
It's better to eat more fat/protein and keep the glucose levels more stable than ride a rollercoaster.
I recommended fewer carbs (and other measures) would lead to higher sensitivity; better blood glucose control.
EDIT: I second enra's comment.
Potatoes are very high, Grapefruit is low. The rest are in between.
That said, it is relevant. Eating low GI and low carb generally is good for the obese and overweight. It'll do wonders against prediabetes and metabolic syndrome because they're insulin insensitive.
[1] Against the GI: http://wholehealthsource.blogspot.com/search?q=glycemic