English term (edited): slow-release carbohydrates

All carbohydrates end up broken down into glucose molecules to be released into the blood stream as fuel. Slow-release carbohydrates go through the same process at a somewhat slower rate. The breaking down of large molecules into simple glucose takes longer. Take a look here:

http://www.formulaforlife.com.au/asp/healthyliving.asp?secti...

"During digestion, both starches and sugars are broken down into glucose, which provides essential energy...

... Slow release carbohydrates help to slow the release of glucose and provide more sustained energy and are therefore preferable."

With this in mind, I suggest:

كربوهيدرات بطيئة التحلل أو الانحلال

One could also use بطيئة الامتصاص or بطيئة التسريب in the sense that the resultant glucose is released into the blood stream at a slower rate.