Glycemic Index
The Glycemic Index (GI) measures how much a food containing 50 grams of available carbohydrate raises a person's fasting blood sugar over the course of two hours. 

Glycemic Index Reference Ranges:

GI Value: (Glucose: 100)
>70                   High
56-69                Moderate
<55                   Low

Factors that affect the Glycemic Index value:

Processing –Grinding wheat into smaller particles increases the surface area for digestive enzymes. The more finely milled the particles are, the higher the glycemic index. For example, the degree of food processing determines the relative glycemic index of wheat (white flour > stone ground wheat > whole wheat).

Fiber –This depends on whether the fiber acts as a protective barrier or not. When fiber plays a protective role to digestive processes as is the case with stone ground (cracked kernel) wheat bread, the glycemic value is lower (53).  Most wheat bread (73) has the same glycemic index as white bread (70) because the fiber is not intact and does not play a protective role.

Gelatinization –The more starch granules swell and burst during cooking, the higher the GI. For this reason, baked potatoes have a high glycemic index (111) whereas pasta is unique in that the internal starch granules are entrapped and not as swollen leading to lower glycemic values (30-60). Pasta cooked al dente (slightly uncooked core) has an even lower glycemic value because of this.

Glycemic Load
Glycemic index does not take serving size into consideration, so a more practical reference is the Glycemic Load (GL). It is calculated by dividing the Glycemic index score by 100, and multiplying the result by the amount of available carbohydrate in a standard serving.

For instance, carrots have a GI of 93 (high), but that number is based on eight or 10 fasting subjects who had to eat one-and-a-half pounds of carrots, because it takes that that many carrots to total 50 grams of digestible carbohydrates (total carbohydrates minus fiber, in grams).   When you consider serving size, carrots' impact on your blood sugar is actually very low (GL= 93/100 x four grams carbohydrate = 4).   This is good news for watermelon too; although the GI is high, at 72, the GL for a four-ounce serving is also 4.

GL Value
> 20                  High
11-19                Moderate
<10                   Low 

If you look at a Glycemic Load values, you'll notice that vegetables, fruits, milk, and whole grain products have low values, and refined foods have high values. So basically, eliminating highly processed foods and replacing them with whole or minimally processed foods is a great way to control blood sugar and to lower CRP levels.