The ‘brick diet’ and postprandial insulin: a practical method to balance carbohydrates ingested and prandial insulin to prevent hypoglycaemia in hospitalized persons with diabetes

Abstract

Aim: Insulin is the preferred treatment for the control of diabetes in hospital, but it raises the risk of hypoglycaemia, often because oral intake of carbohydrates in hospitalized persons is lower than planned. Our aim was to assess the effect on the incidence of hypoglycaemia of giving prandial insulin immediately after a meal depending on the amount of carbohydrate ingested. Methods: A prospective pre–post intervention study in hospitalized persons with diabetes eating meals with stable doses of carbohydrates present in a few fixed foods. Foods were easily identifiable on the tray and contained fixed doses of carbohydrates that were easily quantifiable by nurses as multiples of 10 g (a ‘brick’). Prandial insulin was given immediately after meals in proportion to the amount of carbohydrates eaten. Results: In 83 of the first 100 people treated with the ‘brick diet’, the oral carbohydrate intake was lower than planned on at least one occasion (median: 3 times; Q1–Q3: 2–6 times) over a median of 5 days. Compared with the last 100 people treated with standard procedures, postprandial insulin given on the basis of ingested carbohydrate significantly reduced the incidence of hypoglycaemic events per day, from 0.11 ± 0.03 to 0.04 ± 0.02 (P < 0.001) with an adjusted incidence rate ratio of 0.70 (95% confidence interval 0.54–0.92; P = 0.011). Conclusions: In hospitalized persons with diabetes treated with subcutaneous insulin, the ‘brick diet’ offers a practical method to count the amount of carbohydrates ingested, which is often less than planned. Prandial insulin given immediately after a meal, in doses balanced with actual carbohydrate intake reduces the risk of hypoglycaemia.