Importance of Topic to Practice
Optimal glycemic control is essential in type 1 diabetes for minimizing the risk of micro- and macrovascular complications. Carbohydrate, dietary fat, protein, glycemic index (GI) and eating patterns can also influence postprandial glycemia (1,2).
- Dietary fat delays gastric emptying, which delays the absorption of carbohydrates into the bloodstream and leads to a lag in glucose absorption. For individuals with type 1 diabetes, interindividual variation needs to be taken into consideration when adjusting insulin dose to better match delayed postprandial glycemia.
- Protein causes delayed postprandial hyperglycemia, requiring increased insulin dose and duration to manage postprandial glycemia.
- Low GI meals produce a reduced glycemic response in individuals with type 1 diabetes as in healthy individuals. As such, low GI meals increase the risk of early hypoglycemia and a sustained blood glucose peak in high GI meals.
- Prolonged meals often come in generous portion sizes and nutrients take a longer time to be absorbed and digested by the body. This process may make it more difficult to match the required insulin to this dietary profile when using an insulin pump to deliver the premeal bolus.
What is insulin pump therapy?
Insulin pump therapy, also known as continuous subcutaneous insulin therapy (CSII), is used primarily by individuals with type 1 diabetes mellitus as an alternative to multiple daily insulin injections (MDI). An insulin pump is a small, portable, battery-powered medical device that delivers ongoing small doses of rapid acting insulin based on hour-by-hour settings programmed into the pump to cover basal, or background, insulin requirements, thus eliminating the need for long-acting insulins (1). Additional bolus doses of rapid-acting or ultra-fast-acting insulin are initiated by the user and delivered via the insulin pump to cover meals and snacks, and when required to correct episodes of hyperglycemia (3).
What are the potential pros and cons of insulin pump therapy for individuals with diabetes?
Individuals with diabetes choose insulin pump therapy for a variety of reasons. Potential benefits may include improved glycemic control, reduced fear and experience of hypoglycemia, perceived greater dietary and lifestyle freedom and improved quality of life (4,5).
While many individuals achieve positive outcomes on insulin pumps, many also face difficulties and adverse events (4,5). Some are challenged by the cost of insulin pump consumables, the continuous glucose monitoring consumables required to use hybrid closed-loop features available on some pumps, the complexity of tasks required, such as high level problem solving and adjustment of pump settings. Diabetes-related stress and fatigue may be exacerbated by frequent pump alarms and reminders, including for hyper- and hypoglycemia and boluses (4). Adverse events, such as diabetic ketoacidosis or severe hypoglycemia, may result from pump failure, insulin infusion set blockage, infusion site problems, insulin stability issues, user error or a combination of these (4,5). There have been concerns that regulatory processes across the world do not adequately facilitate dissemination of studies on specific pump models and adverse event data (4).
Whether a person benefits from insulin pump therapy is dependent on a range of factors including pre-existing knowledge, psychological readiness, learning abilities, medical concerns, lifestyle, support networks and pump type/model (5). Individuals at particular risk of adverse events may include those with psychological and social problems, highly disrupted lifestyles and recurrent diabetic ketoacidosis. Overall, it is important to ensure individuals using insulin pump therapy are appropriately supported.
What impact does insulin pump therapy have on glycemic control, frequency of hypoglycemia and quality of life compared to multiple daily injections in adults, adolescents and children?
Compared to multiple daily insulin injections (MDI), insulin pump therapy in children and adults with type 1 diabetes may produce modest improvement in glycemic control, as evidenced by lower A1C levels (-0.3%, 95%CI -0.58 to -0.02%) and reduced severe hypoglycemic events (6-8). However, the evidence base is limited with studies being relatively short and small and it is challenging for research to keep pace with technology. Subsequent studies on sensor-augmented insulin pump therapy have shown to reduce A1C, improve time in range and reduce nocturnal hypoglycemia with the automatic insulin suspend and/or adjustment features (9). Observational studies report mixed findings on glycemic control in pregnant women with type 1 diabetes using insulin pump therapy versus MDI (10,11).
Quality of life and treatment satisfaction has been shown to be improved with insulin pump therapy compared with MDI in a number of studies (8,12,13). A systematic review of RCTs identified four studies (n=98) comparing quality of life, socioemotional condition of parents and treatment satisfaction using insulin pump therapy versus MDI (14). All studies reported improvements, although meta-analysis was not possible due to lack of standardization (14). A subsequent cross-sectional study of pediatric patients with type 1 diabetes in Saudi Arabia also showed that those using insulin pump therapy had greater quality of life across almost all domains, although concurrently higher diabetes-specific worries (including hypoglycemia and medical treatment) (12). Improvements in lifestyle flexibility, dietary flexibility and reduced fear of hypoglycemia are benefits cited by some individuals (15).
Studies in type 2 diabetes and gestational diabetes are limited (14). Lack of significant differences in many RCTs may be due to residual endogenous insulin, which acts to reduce glycemic variability in individuals with type 2 diabetes (14,16). Insulin pump access and consumables may not be publicly-funded for individuals with type 2 diabetes and/or gestational diabetes, which limits uptake and clinical evidence.
Relevant Basic Information
What basal and bolusing features are available?
Insulin pumps offer a range of basal and bolus features for the fine tuning of diabetes management. Different basal rates can be programmed throughout the day, and temporary rates can be applied for ad-hoc situations such as sports activities (13). In hybrid closed loop systems, an insulin pump is paired with a continuous glucose monitor to auto-regulate basal rates based on fluctuating glycemia within a certain range. This is known as “auto-mode” operation. In contrast, defaulting to pre-programmed basal rates is known as “manual mode”. In auto-mode, if glucose levels drop below specified targets, the pump will alarm and automatically suspend insulin to prevent hypoglycemia. If blood glucose is predicted to rise above target levels within the half hour, the pump will alarm and deliver microboluses to prevent hyperglycemic events. If alarms are ignored and no user interaction has occurred within the specified timeframe, the pump will default to manual mode until the user has acknowledged the alarm state. Bolus insulin doses for meals must be given manually in both auto-mode and manual-mode, as automatic algorithms are not yet available to address the rapid rise in glycemia following food intake.
Insulin pumps using manual mode offer three options for bolus delivery. A normal wave (standard, express, scroll bolus) delivers the total insulin dose at once (17). Square wave (extended bolus) delivers insulin evenly over a user-identified period of time. Dual wave (multi-wave, combination wave) is a combination or percentage of the total bolus given as an immediate, normal bolus followed by an extended bolus over a user-identified period of time. In auto-mode, square-wave and dual-wave bolus insulin delivery options are no longer available.
How should a dietitian assess readiness for insulin pump therapy and what education should be provided in preparation?
When considering an individual for insulin pump therapy, the diabetes management team, including a dietitian, will usually explore the following readiness indicators (18,19):
- interest in and willingness to optimize glycemic control
- realistic expectations of the benefits of insulin pump therapy and awareness of potential challenges
- level of comfort with the idea of wearing and using an insulin pump
- mathematical and technological abilities required for successful insulin pump operation
- willingness to commit to self-management of blood glucose (SMBG) and keep detailed diabetes records; including frequent blood glucose monitoring, ketone monitoring, measured food portions, accurately calculated carbohydrate quantities and lifestyle factors that may impact on blood glucose results
- ability to finance the costs of insulin pump therapy
- access to a diabetes care team with expertise in insulin pump therapy that can provide ongoing education and support.
The dietitian’s role in preparation for insulin pump therapy includes (20):
- an initial nutrition assessment including current nutrition knowledge, past and present diet approaches and carbohydrate counting skills
- education, if required, on current carbohydrate counting techniques and supporting resources
- ongoing monitoring and education.
Dietitians need to be appropriately trained in insulin pump therapy and carbohydrate counting (19,20). Furthermore, in some practice settings, dietitians may undertake additional training that enables them to provide advice on insulin dosing in addition to dietary advice. Insurance coverage, medical directives and required qualifications should be clarified before a dietitian expands their scope of practice in this way.
What knowledge and skills should be evaluated/reviewed with individuals using insulin pump therapy?
Individuals should be assessed by their diabetes management team on a regular basis (at least annually), as failure to apply appropriate strategies (such as carbohydrate counting, glucose monitoring, ketone testing, correction dosing, insulin delivery and back-up insulin supplies) can result in recurring episodes of hyperglycemia and/or hypoglycemia (18). Continued/refresher education should be provided as needed. In particular, individuals need to understand:
- the delay between insulin delivery and the subsequent impact on blood glucose
- basal delivery and application of temporary basal rates
- bolus insulin delivery such as bolus types and calculators, insulin to carbohydrate ratios, insulin sensitivity/correction factors; insulin action time; glucose target range
- accurate carbohydrate counting techniques; including the use of relevant apps, validity of websites, food lists, food labels, food scales and recipe calculations.
How should mealtime insulin doses be calculated when using an insulin pump?
Traditionally, carbohydrate counting has been the cornerstone of mealtime insulin dose calculations in type 1 diabetes. On fixed insulin doses, individuals are encouraged to count carbohydrates in order to achieve a stable intake and distribution from day to day. Others apply advanced carbohydrate counting techniques to facilitate flexibility with eating patterns through the use of insulin to carbohydrate ratios. Different types of meals, eating patterns and macronutrient portions influence postprandial glycemia beyond carbohydrate loading alone. For example, multiple studies show the benefits of additional insulin dosing to cover high fat and protein loads above the carbohydrate requirement (16). Research supports an increase of prandial insulin given at least 10 minutes prior to the start of a meal that is higher in fat and protein, suggesting it may help to improve two-hour postprandial blood glucose results (21,22). The optimal dose increase for these loads has yet to be determined and likely varies between individuals.
Should individuals using insulin pump therapy bolus for snacks?
Whether additional insulin doses are required to cover carbohydrate snacks to optimize postprandial glycemia is dependent on the carbohydrate content. Smart et al. has shown that 10 g variations in carbohydrate content do not significantly affect postprandial glycemia, whereas 20 g carbohydrate variations cause significantly more hyperglycemia (23,24). Furthermore, Vanderwel et al. has shown missed boluses with snacks are common but contribute to significantly higher glucose excursions (25). Based on these studies (23-25), it is suggested that individuals on pump therapy bolus for snacks containing 20 g of carbohydrate or more.
Registered dietitians should consult the regulatory body in their jurisdiction for more information regarding scope of practice for providing and teaching insulin dose adjustment.
Resources for Professionals
- Bell KJ, Smart CE, Steil GM, Brand-Miller JC, King B, Wolpert HA. Impact of fat, protein, and glycemic index on postprandial glucose control in type 1 diabetes: implications for intensive diabetes management in the continuous glucose monitoring era. Diabetes Care. 2015;38(6):1008-15. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/25998293/
- Metwally M, Cheung TO, Smith R, Bell KJ. Insulin pump dosing strategies for meals varying in fat, protein or glycaemic index or grazing-style meals in type 1 diabetes: A systematic review. Diabetes Res Clin Pract. 2020 Oct 20:108516. Doi: 10.1016/j.diabres.2020.108516. Epub ahead of print. PMID: 33096184. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/33096184/
- Aleppo G. Insulin Pump Overview. Endocrine Web. 2019 Mar 5. Available from: https://www.endocrineweb.com/guides/insulin/insulin-pump-overview
- Heinemann L, Fleming GA, Petrie JR, Holl RW, Bergenstal RM, Peters AL. Insulin pump risks and benefits: a clinical appraisal of pump safety standards, adverse event reporting, and research needs: a joint statement of the European Association for the Study of Diabetes and the American Diabetes Association Diabetes Technology Working Group. Diabetes Care. 2015;38(4):716-22. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/25776138/
- Pickup J, Keen H. Continuous subcutaneous insulin infusion at 25 years: evidence base for the expanding use of insulin pump therapy in type 1 diabetes. Diabetes Care. 2002;25(3):593-8. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/11874953/
- Misso ML, Egberts KJ, Page M, O’Connor D, Shaw J. Continuous subcutaneous insulin infusion (CSII) versus multiple insulin injections for type 1 diabetes mellitus. The Cochrane database of systematic reviews. 2010(1):Cd005103. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/20091571/
- Qin Y, Yang LH, Huang XL, Chen XH, Yao H. Efficacy and Safety of Continuous Subcutaneous Insulin Infusion vs. Multiple Daily Injections on Type 1 Diabetes Children: A Meta-Analysis of Randomized Control Trials. J Clin Res Pediatr Endocrinol. 2018 Nov 29;10(4):316-323. Doi: 10.4274/jcrpe.0053. Epub 2018 Jul 17. PMID: 30015622; PMCID: PMC6280319. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/30015622/
- Pala L, Dicembrini I, Mannucci E. Continuous subcutaneous insulin infusion vs modern multiple injection regimens in type 1 diabetes: an updated meta-analysis of randomized clinical trials. Acta Diabetol. 2019 Sep;56(9):973-980. doi: 10.1007/s00592-019-01326-5. Epub 2019 Apr 3. PMID: 30945047. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/30945047/
- American Diabetes Association. 7. Diabetes Technology: Standards of Medical Care in Diabetes-2020. Diabetes Care. 2020 Jan;43(Suppl 1):S77-S88. Doi: 10.2337/dc20-S007. Erratum in: Diabetes Care. 2020 Aug;43(8):1981. PMID: 31862750. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/31862750/
- Ranasinghe PD, Maruthur NM, Nicholson WK, Yeh H-C, Brown T, Suh Y, et al. Comparative effectiveness of continuous subcutaneous insulin infusion using insulin analogs and multiple daily injections in pregnant women with diabetes mellitus: a systematic review and meta-analysis. J Womens Health (Larchmt). 2015;24(3):237-49. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/25713996/
- Yamamoto JM, Murphy HR. Technology and Pregnancy. Diabetes Technology & Therapeutics. 2019;21(S1):S-101-S-11. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/32069145/
- Al Shaikh A, Al Zahrani AM, Qari YH, AbuAlnasr AA, Alhawsawi WK, Alshehri KA, et al. Quality of Life in Children With Diabetes Treated With Insulin Pump Compared With Multiple Daily Injections in Tertiary Care Center. Clin Med Insights Endocrinol Diabetes. 2020;13:1179551420959077. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/33088186/
- Opipari-Arrigan L, Fredericks EM, Burkhart N, Dale L, Hodge M, Foster C. Continuous subcutaneous insulin infusion benefits quality of life in preschool-age children with type 1 diabetes mellitus. Pediatric Diabetes. 2007;8(6):377-83. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/18036064/
- Medical Advisory Secretariat. Continuous Subcutaneous Insulin Infusion (CSII) Pumps for Type 1 and Type 2 Adult Diabetic Populations: An Evidence-Based Analysis. Ontario health technology assessment series. 2009;9(20):1-58. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/23074525/
- Casas-Oñate ML, Montoya-Martínez D. [Influence of the treatment with continuous subcutaneous insulin infusion (CSII) in the improvement of the quality of life of patients with type 1 diabetes mellitus]. Enfermeria clinica. 2010;20(4):216-21. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/20561806/
- Monami M, Lamanna C, Marchionni N, Mannucci E. Continuous subcutaneous insulin infusion versus multiple daily insulin injections in type 2 diabetes: a meta-analysis. Experimental and clinical endocrinology & diabetes: official journal, German Society of Endocrinology [and] German Diabetes Association. 2009;117(5):220-2. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/19301231/
- Lopez P, Smart C, Morbey C, McElduff P, Paterson M, King BR. Extended insulin boluses cannot control postprandial glycemia as well as a standard bolus in children and adults using insulin pump therapy. 2014;2(1):e000050. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/25489486/
- Jenkins E, Knott J, Brooks A. Insulin pump users require recurrent education for the management of pump failure. J Diabetes Nurs. 2016. Available from: https://www.woundsinternational.com/resources/details/insulin-pump-users-require-recurrent-education-for-the-management-of-pump-failure
- Berget C, Messer LH, Forlenza GP. A Clinical Overview of Insulin Pump Therapy for the Management of Diabetes: Past, Present, and Future of Intensive Therapy. Diabetes Spectr. 2019 Aug;32(3):194-204. doi: 10.2337/ds18-0091. PMID: 31462873; PMCID: PMC6695255. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/31462873/
- Rubin, RC. Insulin pumps in diabetes management. Today’s Dietitian. 2013;15(2):50. Available from: https://www.todaysdietitian.com/newarchives/021313p50.shtml
- Slattery D, Amiel SA, Choudhary P. Optimal prandial timing of bolus insulin in diabetes management: a review. Diab Med. 2018;35(3):306-16. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/29044708/
- Paterson MA, Smart CEM, Howley P, Price DA, Foskett DC, King BR. High-protein meals require 30% additional insulin to prevent delayed postprandial hyperglycaemia. Diab Med. 2020;37(7):1185-91. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/32298501/
- Smart CE, King BR, McElduff P, Collins CE. In children using intensive insulin therapy, a 20 gram variation in carbohydrate amount significantly impacts on postprandial glycaemia. Diab Med. 2012;29(7):e21-4. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/22268422/
- Smart CE, Ross K, Edge JA, Collins CE, Colyvas K, King BR. Children and adolescents on intensive insulin therapy maintain postprandial glycaemic control without precise carbohydrate counting. Diab Med. 2009;26(3):279-85. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/19317823/
- Vanderwel BW, Messer LH, Horton LA, McNair B, Cobry EC, McFann KK, et al. Missed insulin boluses for snacks in youth with type 1 diabetes. Diabetes Care. 2010;33(3):507-8. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/20032279/