The Glycemic Index (GI) and Glycemic Load (GL) are tools for understanding how carbohydrates affect blood sugar — with important distinctions between them.

Glycemic Index (GI):

• Ranks foods 0–100 based on how quickly they raise blood glucose compared to pure glucose (GI=100)
• Low GI: <55 (lentils, most fruits, vegetables)
• Medium GI: 56–69 (whole wheat bread, brown rice)
• High GI: >70 (white bread, white rice, potatoes, sugary drinks)

Glycemic Load (GL) = GI × carbs per serving ÷ 100:

• Accounts for serving size, which GI ignores
• Watermelon has high GI (72) but low GL (4) — because a serving has little carbs

Practical use:

• Low GI/GL diets improve blood sugar control in diabetics
• Combining carbs with fat, protein, or fiber lowers the effective GI of a meal

Reference:

Wikipedia: Glycemic index

https://en.wikipedia.org/wiki/Glycemic_index