Walter Willet, nutrition chair of the Harvard School of Public Health, published a study, which found that women who ate more whole grains had a lower risk of diabetes. The women who ate the most sugar and refined carbohydrates such as white bread, pasta and potatoes had the highest risk of diabetes, as much as 2.5 times more. He also emphasized that whole grains have a different effect in the body as compared to refined carbohydrates. In general, the less refined the food, such as whole grains and legumes, the less rapidly they are digested, and thus they enter the body's system much slower. This decreases the body's production of insulin, puts less stress on the body and thereby lowers the glycemic load. All of this lowers one's risk of developing diabetes.
http://www.calolive.org/foodservice/findings/findings_2004q1.html#8
High GI carbohydrate foods (eg. refined white flour foods) tend to have a chemical structure which permits digestive enzymes easy access, which means these carbs are rapidly converted to glucose and, on entry into the bloodstream, cause a rapid rise in blood sugar ("sugar spike"). In turn, this rapid glycemic reaction triggers an equally large secretion of the pancreatic hormone insulin, whose function is to get the glucose out of the blood and into the cells/muscles where it is utilized to provide energy for the body. Unfortunately, this sort of increased demand on the pancreas and the presence of large amounts of insulin in the blood is neither healthy (it may lead to hyperinsulimia and impaired glucose tolerance) nor good for weight management (it creates renewed hunger within a couple of hours). Until the invention of the glycemic index and associated glycemic load, sugar was thought to be the main cause of "sugar spikes". Now however, it is clear that refined white flour foods are the main culprit.
http://www.carbs-information.com/gi-values-carbohydrates.htm
Starch is a Complex Carbohydrate
Because the molecular structure of complex carbohydrates is more complicated, than more simple carbohydrate sugars, like sucrose and glucose, the body cannot metabolize complex carbs into energy as quickly as simple carbs. Result? Complex carbs are not digested and turned into energy as fast as sugars (except for fructose) and therefore keep us full for longer.
Starch is an Intermediate or High Glycemic Index Food
However, the classification of carbs into "simple" or "complex carbs" has been superceded by the Glycemic Index, which rates carbs according to their effect on blood-glucose levels. Many starchy foods (eg. potatoes) are now classified as intermediate or high-glycemic-index foods and should (for best effects on blood-sugar and insulin sensitivity) be eaten in combination with lower glycemic index foods.
http://www.carbs-information.com/starch.htm
From the above info it seems that even though chickpea flour and white wheat flour have a high carb [starch] content they are high on GI. OTOH whole grain are low on GI because they have more fibre. [correct me if I am wrong] But fibre doesnt give energy.
The question I have is how much should I be concerned about high GI food? If I snack at regular intervals -say 1hour can I maintain my glucose levels by eating starchy food? How do I determine optimum interval?