Can a vegan diet help people with type 1 diabetes save on insulin? A secondary analysis of a 12-Week randomized clinical trial | BMC Nutrition

In this study, compared to a portion-controlled diet, a low-fat vegan diet, with no limits on calories or carbohydrate intake, reduced the total daily insulin use by 28% in people with type 1 diabetes, with concomitant improvements in glycemic control. Total daily insulin costs decreased by 27% in the vegan group, compared to no significant change in the portion-controlled group.

The reductions in insulin use in the vegan group likely reflect improved insulin sensitivity, resulting from the reduction in liver and muscle fat [5]. This lower insulin use on the low-fat vegan diet reflects a marker of improved cardiometabolic health [6] and of reduced treatment costs, in addition to the likelihood of lower food costs on a vegan diet, as previously reported [7].

In a retrospective study of United Healthcare patients (2015–2017) that included 12,700 people with type 1 diabetes, the average yearly medical costs to the payer totaled $18,800 per person with type 1 diabetes, $4,600 higher than the cost of treating a person with type 2 diabetes, and far higher than for those without diabetes. Of the costs associated with type 1 diabetes, the average prescription costs were $10,200 (±$11,000) per person per year [2]. In another retrospective study using 2011–2016 IBM MarketScan and electronic medical record data, the average cost per person with type 1 diabetes per year was approximately $9,600. The majority of these costs (55%-61%) were due to pharmacy costs [8].

Insulin prices have been increasing steadily and are projected to increase even further, despite efforts to rein in such costs. Between 2014 and 2019, the average price of insulin in the US increased by 55%, from $3,819 to $5,917 per year [9]. The out-of-pocket costs of insulin differ greatly depending on the population and the type of insurance. In a 2018 IBM Marketscan Database study of 65,000 people with type 1 diabetes covered by private insurance, the average annual out-of-pocket cost per person using insulin varied between $472 (±$625) and $1,037 (±$1,039) [10]. The yearly out-of-pocket insulin costs for Medicare Part D recipients increased from approximately $588 in 2014 to $696 in 2019 [9]. These studies highlight the need for interventions that will help people with type 1 diabetes save on the cost of insulin. A low-fat vegan diet appears to be a promising option, partly due to its ability to reduce body weight and ectopic fat, and to increase insulin sensitivity.

The strengths of this study include the randomized parallel design, in which all participants started simultaneously, allowing the investigators to rule out possible effects of seasonal fluctuations in the diet. The study duration was reasonably long, providing sufficient time for adaptation to the diet. A vegan diet is healthy and nutritionally adequate, and provides all the needed nutrients and macronutrients, except for vitamin B12, which needs to be supplemented [11]. Given that the participants were living at home and preparing their own meals or eating at restaurants, our results are applicable outside the research setting, in free-living conditions.

The study also has important limitations. Dietary intake was calculated based on self-reported diet records, which have well-known limitations [12], but this was partly offset by the repeated collection of the dietary data by each participant. That means that participants served as their own controls for the dietary data collected at different time points, which minimized the impact of inter-individual differences. The same applies to the self-reported insulin data. While the 3-day average only represents a snapshot of the overall insulin use, it has been found to be a fairly accurate representation, which has allowed people with diabetes to achieve comparable glycemic control as with physician-directed titration [13]. Furthermore, the study requirements included careful meal and blood glucose monitoring for research purposes, beyond that required for self-care, which contributed to a substantial attrition rate. The small sample size was modest, and the study duration was limited. Prices for short-acting and long-acting insulins vary over a wide range, which may explain why the between-group difference in insulin price did not reach the statistical significance, although the groups differed in total insulin dose. The expenses associated with dietetic instruction and may or may not be covered by insurance. However, all individuals with type 1 diabetes receive dietetic instruction, and these costs would be expected to be similar, regardless of diet type. Some may supplement instruction with free resources, such as books and pre-recorded videos. Finally, our participants were health-conscious volunteers and may not be representative of the general population, but they are likely representative of individuals seeking clinical care.