Mealtime insulin doses need to be increased by up to 20% for high fat meals because the amount of fat consumed has a dose-response relationship with postprandial glycaemia, Australian research shows.

Insulin also needs to be dosed as a dual-wave to optimise the glycaemic response to higher fat meals, according to Dr Kirstine Bell and colleagues at the University of Sydney’s Charles Perkins Centre.

In a dietary study involving 19 volunteers with T1D over 12 research visits, the researchers found that the type of fat (saturated, mono-unsaturated, polyunsaturated) consumed in a meal had  no clinically significant impact on postprandial glycemia.

But increasing amounts of fat in 20g increments resulted in significant lowering of the early postprandial glucose response and raising the late postprandial response in individuals who received the same insulin dose, the study found.

While the overall Area Under the Curve (AUC) for glucose and peak blood glucose level did not change with increasing amounts of fat in a meal, the time to peak glycaemia was progressively lengthened with increasing amounts of fat.

The study findings showed the optimal insulin dosing for increasing fat intake would be a 75/25% split over 11/4 h for a 20-g fat meal, changing to a 65/35% split over the same time period for a 40-g fat meal, and finally a 50/50% split over 13/4 h for a 60-g fat meal.

“The results suggest a threshold for dietary fat, with 20% more insulin dose required for 60 g fat with carbohydrate,” the researchers wrote in Diabetes Care.

They said the findings could be used to produce optimised bolus algorithms for dietary fat to be programmed into insulin pumps.

“To translate these findings into clinical practice, user-friendly, decision support tools are needed in order to ensure that improvements in glycemic control do not come at the expense of increased burden of disease,” they wrote.

“Given the difficulties and burden already associated with counting carbohydrate, we propose a novel bolus calculator with an integrated nutrition database would negate the need for any in-depth nutrition knowledge, counting multiple macronutrients or complex calculations.”

Speaking to the limbic, Dr Bell said it was important to acknowledge that people with T1D were eating higher fat meals and so practical solutions were needed to help manage blood glucose levels.

“This research provides general guidelines for how to adjust insulin for high carbohydrate, high fat meals.  However, just as dosing for carbohydrate varies between people with type 1 diabetes, insulin dosing for dietary fat also needs to be tailored to the individual,” she said.