Novel food insulin index algorithm improved glycemic control

CHICAGO – A novel food insulin index algorithm appears to be a safe and useful tool for estimating the mealtime insulin dose in type 1 diabetic patients, without the need for counting carbohydrates, according to Dr. Stephen Colagiuri.

Application of the food insulin index algorithm to common protein-containing foods produced lower postprandial blood glucose levels without significantly increasing the risk of hypoglycemia in a small, triple-randomized crossover comparison study, he reported at the annual scientific sessions of the American Diabetes Association.

Similar in concept to the glycemic index, the food insulin index (FII) is an algorithm for ranking foods based on their insulin demand relative to a reference food. When compared with carbohydrate counting in a prior study involving 28 patients with type 1 diabetes using insulin pump therapy, the algorithm significantly improved the percentage of time within the normal blood glucose range without a significant difference in the incidence of hypoglycemia (Diabetes Care 2011;34:2146-51).

^{Patrice Wendling/IMNG Medical Media}

Dr. Stephen Colagiuri

The aim of the current study was to compare carbohydrate counting with the FII algorithm for estimating insulin dosage on postprandial glycemia in adults with type 1 diabetes consuming six single foods. The six foods – low-fat strawberry yogurt, salted peanuts, baked beans, poached eggs, beef steak, and battered fish fillets – were chosen to represent a cross-section of common protein-containing foods with at least a twofold difference between their carbohydrate content per serving and estimated food insulin demand (FID), explained Dr. Colagiuri, professor of metabolic health, University of Sydney (Australia).

FID extends the FII concept by combining a food’s FII with the kilojoule in the portion size. Unlike the FII, which is a fixed value, FID changes as the food portion size changes, and can therefore be used to determine the mealtime insulin dose, similar to the calculation of the insulin to carbohydrate ratio, he said.

For example, if one consumes 200 g of low-fat strawberry yogurt, that’s 770 kJ for the portion size, which is multiplied by an FII of 84 for the yogurt and then divided by 1,000, resulting in an FID of 65.

Eleven adults with type 1 diabetes on insulin pump therapy consumed one of the six foods and were administered with an insulin dose determined by either the FID or carbohydrate counting. Postprandial glycemia was measured through capillary glucose samples at regular intervals over a 3-hour period.

The patients’ mean diabetes duration was 14.4 years, their mean insulin pump therapy duration was 3.6 years, and their mean hemoglobin A_1c level was 7%. Their average body mass index was 24.6 kg/m², and their mean age was 38.

Compared with carbohydrate counting, the FID significantly reduced mean blood glucose level (5.7 mmol/L vs. 6.5 mmol/L; P = .003), produced a smaller mean change in blood glucose level (–0.7 mmol/L vs. 0.1 mmol/L; P = .001) and trended toward a smaller peak change in blood glucose excursion (1.3 mmol/L vs. 1.8 mmol/L; P = .10), reported the investigators, led by Kirstine Bell, a diabetes educator and PhD candidate at the University of Sydney.

The risk of hypoglycemia over the 3-hour period was not significantly different, at 22 events with carbohydrate counting and 32 events with the FID (33% vs. 48%).

A study is planned to evaluate the FID in adolescents, and another is ongoing and is looking at the FID in everyday use among 36 adults with type 1 diabetes. Several resources, including an iPhone app, pictorial guides and a website have been developed to help support patients in using the FID, Ms. Bell said in an interview.

"It is essentially very similar to carbohydrate counting," she said. Just as patients would learn that a slice of bread has so many grams of carbohydrates, "they’d simply learn that a slice of bread has this much FID," she said. The FIDs are then added up and put into the patient’s pump, which is programmed to create an insulin-to-FID ratio, just as it does an insulin-to-carbohydrate ratio.

While the iPhone app doesn’t have the functionality yet to calculate an FID based on a food photo, patients can look up 130 commonly consumed foods in the United States that have been tested by the team and entered into their database. Patients can then input their serving size, and it will calculate the FID for them.

The authors reported no relevant financial disclosures.

pwendling@frontlinemedcom.com