Many still believe that GI as the sole factor that determines the glycemic response. In many countries, including the United States, food items are often labelled as "low glycemic index," "diabetic food," "diabetes friendly," and so forth, as if GI is the only factor that will influence the glycemic response (GR). Patients and health professionals give importance to GI rather than using a holistic approach of glycemic response.

The American Diabetes Association advises patients that, for most people with diabetes, the first tool for managing blood glucose is carbohydrate counting. Nevertheless, the type of carbohydrate significantly affects the blood glucose level, so using the GI together with carbohydrate counting seems helpful in "fine-tuning" blood glucose management. Therefore, the use of GI in combination with carbohydrate counting is likely to provide additional benefits for patients in achieving blood glucose goals, especially for those who are willing to put extra effort into monitoring their food choices [10].

However, many factors other than caloric count affect the glycemic response following a carbohydrate meal. Table 2 provides factors that would affect theglycemic response of carbohydrates.

Available carbohydrate

If three different carbohydrates having 50 g of total carbohydrates per 100 g of food are ingested, variable amounts of a percentage percentage of total carbohydrate ingested will be absorbed. Depending on the type of carbohydrate and the availability of fiber contents in the food ingested, the percentage absorbed will vary. The percentage that is absorbed from total carbohydrate is generally identified as the "available carbohydrate." However, food labels indicate the total carbohydrate in a given food. When patients try to count their carbohydrate content, food labels are likely to give misleading information.

Effects of other food and vegetables on carbohydrates absorption and the glycemic response in a mixed meal

Most of the studies on carbohydrates have been done using pure carbohydrate meals, rather than complex, mixed meals such as patients would generally eat. Others have shown that dietary fat and protein reduced the glycemic response of carbohydrates in a mixed meal [11]. It has been shown that adding green vegetables could reduces the glycemic response of a particular carbohydrate. For example, the GI could be reduced by as much as 40% by addition of vegetables to a carbohydrate meal [4]. This is an important factor when it comes to differences in GI between similar carbohydrates.

For example, in rice varieties, the GI of Basmati rice and brown rice are given undue prominence by traders as well as medical community. When over 200 varieties of rice was tested, the GI values were found to be vary different. Even within similar varieties of rice, there is a wide variation in GI. For example, there are varieties of Basmati rice with high and some with low GI values [12]. Promoting a particular rice variety without considering other factors, such as duration of cooking time, water content, and inclusion of other foods such as vegetablesand proteins could be misleading and thus, would not help patients with diabetes.

They may purchase Basmati rice assuming as low GI rice GI but may end up buying a type of Basmati rice with a high GI value. Thus, the principle of glycemic response is more complicated. In addition, the importance of adding vegetables and proteins to carbohydrate meals should be emphasized to patients with diabetes. There are other factors affecting the GI of a carbohydrate diet. For example, in normal subjects as well as patients with diabetes, it has been shown that when a carbohydrate meal is eaten with watery gravy, the glycemic response increases [13,14].

Series of studies were conducted by KAN, using carbohydrate meals made up of flour from brown rice and white rice and compared the GR with and without the addition of curries made from gravy, fish, lentils, and green beans. Higher GR was observed when meals were eaten with gravy. When fish and green beans were added, there was a reduction of approximately 30% to 40% in the GR. This difference nullified the GI advantage of GI observed with brown rice [4]. These data led us to hypothesize that consuming water just before or a quantity of gravy with rice together with meals might increase the GI of a carbohydrate meal. In fact, other studies support the theory that consuming water just before, during, or after a carbohydrate meal, increases the absorption of carbohydrates [14,15]. This theory needs to be scientifically tested.

Biscuits as snacks in diabetes

The original paper on GI by Jenkins and colleagues showed a medium glycemic response to biscuits [6]. However, this study was done with 50 g of carbohydrate, which is not how people eat in dayto-day life. In real life, a subject will eat a few biscuits at a time. Each time, the quantity may not reach the level of 50 g of carbohydrates. If biscuits are given in the quantities normally consumed by patients with diabetes, the glycemic response observed are likely to be different.

Apparent volume of food after cooking

When healthcare workers teach patients about a diabetes diet, that usually depend on food items with approximately 25 g of "available" carbohydrate, which needs to be reflected by the right portion size fora given patient with diabetes. We observed that when a fixed quantity of the same carbohydrate (e.g., wheat flour) is used to cook various food items, such as pasta, noodles, string hoppers and flat bread, the apparent volume of the cooked food varies significantly. When measured the post-cooked volume of a wheat flour-based product and compared it with same quantity of cooked rice, the post-cooked volume of rice is higher, providing a bigger "apparent" volume without change in caloric count. This simple but important phenomenon has not been considered in clinical studies before. It is in part attributable to different quantities of water being absorbed during cooking, the speed of cooking, and different volumes of air space in some food items. This finding has important implications for patients because they serve themselves (e.g., a portion of rice) depending on the apparent volume of the food, rather than the real weight or caloric content. Therefore, to prevent misguiding patients, when a healthcare worker prescribes a diet with GI/GL, consideration of the post-cooked apparent volume of food (portion size) should to be considered.

Carbohydrate counting and DAFNE (dose adjustment for normal eating course and carb counting)

Carbohydrate counting for diabetes is a popular diet method in most Western societies. In DAFNE courses, patients are trained to count their carbohydrate intake at every meal and advised to inject 1 to 3 units of ultra-short-acting insulin for every 10 g of carbohydrates ingested. There is evidence that patients who are carb counting have better glycemic control. However, when carb counting is performed, total carbohydrate is considered, and the available carbohydrate is not considered or calculated. Neither the addition of fat, proteins, and vegetable fiber are taken into account in the glycemic response of that particular food [15].

Therefore, DAFNE courses could be further improved if minor details of carb counting could be included in the teaching. Patients should be systematically taught about other factors that affecting the GR and how they can calculate the amount of available carbohydrates in their diet. Every patient with diabetes may not be motivated or capable to learn the minor details of medical nutrition therapy, going beyond simple carbohydrate counting. However, committed patients who may want to fine-tune their diabetes treatment should be offered additional training in this regards.