The effect of protein and fat meal content on the insulin requirement of type 1 diabetic children

Abstract

BACKGROUND AND AIMS : In type 1 diabetes, post-prandial hyperglycaemia remains a major challenge. Determining meal bolus insulin is mainly dependent on carbohydrate counting and the carbohydrate content of a meal. Recent studies have shown this method to be ineffective at times. Also, it has been proven that the fat and protein contents of meals demand insulin as well. The aim of this study was to determine the true post-prandial glycaemic response and total insulin need for mixed meals with known, constant carbohydrate content but different fat and protein contents, using insulin pump therapy and continuous glucose monitoring (CGM) in children with type 1diabetes. RESEARCH DESIGN AND METHODS : A total of 22 participants aged four to 17 years with type 1 diabetes on insulin pump therapy took part in this home-based, cross-over, randomised controlled trial. They were given two meals at dinner time on different nights. Both meals had identical carbohydrate content but one was a low-fat, low-protein (LFLP) meal and the other a high-fat, high-protein (HFHP) meal. CGM and finger prick testing were done for 10 hours post-meal, with correction bolus insulin given every two hours if required. RESULTS : The HFHP meal required significantly more insulin than the LFLP meal, namely eight times more post-meal correction insulin (1.2 vs. 0.15 units) and 1.3 times (30%) more total meal insulin (3.48 vs. 2.7 units). The HFHP meal increased the duration of digestion (364 vs. 185 min) and led to a significantly larger area under the blood glucose response curve (AUC) (198 vs. 46.3). Protein and fat both influenced total meal and correction insulin requirements, and a correction of 1 unit insulin for every 8g protein and 1 unit for every 4g fat, in a mixed meal, was observed. Insulin requirement and glucose responses were, however, also influenced by patient characteristics, independent of the meals. The participants‟ total correction insulin requirements were significantly influenced by the duration of diabetes and their total daily insulin use (units/kg). Peak CGM and AUC were influenced by duration of diabetes and total daily insulin use (units/kg) as well as HbA1c (AUC only). In addition, a significant interaction was noted between the test meals and duration of diabetes in terms of peak sensor glucose value (p=0.014) and between duration of diabetes (p=<0.0001), total daily insulin use (u/kg) (p=0.003) and HbA1c (p=0.003) in terms of AUC. The difference in peak CGM and AUC between the two test meals was larger in individuals who have had diabetes for longer and those with a higher total daily insulin use. CONCLUSION : Children with type 1 diabetes on insulin pump therapy require more insulin over a longer period of time when consuming mixed meals than the insulin requirement calculated with current regimes. HFHP meals required insulin up to six hours post-meal, while LFLP meals required insulin up to three hours post-meal. Fat required double the amount of correction insulin compared to protein. However, the amount of additional insulin required is influenced by duration of diabetes and total daily insulin use.