Type 1 diabetes accounts for about 10% of all adults with diabetes. It can only be treated successfully by replacing the insulin deficiency. The presenting features of type 1 diabetes are those of hyperglycaemia and insulin deficiency.
First published September 2016, updated March 2022
Type 1 diabetes is an auto-immune condition characterised by insulin deficiency. The pathogenesis is immune-mediated destruction of the insulin producing beta cells of the islets of Langherhans in the pancreas. Typically, the onset is in childhood with a peak incidence in the early teenage years. However, true type 1 diabetes can occur at any age—the oldest person in whom I have made the diagnosis was 92 years old.
The presenting features of type 1 diabetes are those of hyperglycaemia and insulin deficiency. In young people the symptoms are of relatively abrupt onset with rapidly worsening thirst, polyuria and weight loss. The diagnostic feature of type 1 diabetes is ketone production. Persistent urinary ketones greater than + on urine dip, or persistent blood ketones above 1.5mmol/L makes the diagnosis of type 1 diabetes very likely, whatever the age of the patient. The clinical picture can be more insidious in older people with late onset type 1 diabetes, who can appear to tolerate the loss of insulin production with less florid symptoms and can be free of ketones at presentation.
Weight loss in adults with newly diagnosed diabetes suggests insulin deficiency and should prompt further investigation as well as monitoring for ketones; type 2 diabetes is rarely associated with weight loss at presentation. Adults with a history of alcohol excess, previous pancreatitis, or nonautoimmune pancreatic pathology whatever the cause, can present with features of insulin deficiency, but this is not true type 1 diabetes, though may require insulin therapy. Pancreatic imaging to exclude malignancy may be appropriate if there is a suspicion of non-autoimmune pancreatic pathology.
In recent times the ability to measure specific auto-antibody titres for glutamic acid decarboxylase (GAD), islet cell antigen-2 (IA-2) antibodies, and pancreatic islet cell antibodies can assist diagnosis in cases where the clinical presentation is unclear. Antibody testing is most likely to be positive at the time of diagnosis. The development of these tools led to the realisation that many people previously diagnosed with type 2 diabetes may in fact have a slow onset form of auto-immune diabetes that has been described as latent auto-immune diabetes of adults (LADA).
People with LADA have true type 1 diabetes with a relatively slow rate of beta cell destruction. After a period of treatment with oral agents weight loss and ketosis occur requiring treatment with insulin. At this point the serum C-peptide will be low or absent and this can be a useful test in people who have been managed initially on oral agents and subsequently develop features of insulin deficiency, when autoantibody titres may have declined.
Type 1 diabetes can only be treated successfully by replacing the insulin deficiency. Oral and nasal insulin replacement therapy has not yet been sufficiently refined to provide optimal glycaemic control. Therefore, in type 1 diabetes insulin is administered subcutaneously, usually by intermittent bolus injection. Optimal modern management, whatever the age of onset, consists of:1
- Education in type 1 diabetes self-management skills by suitably trained diabetes specialist nurse and dietician n Patient-led capillary blood glucose monitoring
- Twice-daily intermediate or long acting insulin as background cover
- Pre-prandial rapid acting analogue insulin before consuming any food containing 10g or more of carbohydrate with dose titrated to a specified target blood glucose range
- Regular screening for early treatable signs of diabetes complications.
This insulin regimen tends to be referred to as multiple dose insulin (MDI) therapy. The use of continuous subcutaneous insulin infusion (CSII or pump) therapy is increasing, particularly in infants and young children where it has become almost routine. In adults, CSII therapy is not first line, and is reserved for people with specific complicating features such as disabling recurrent hypoglycaemia, hypoglycaemia unawareness, and clinical scenarios where MDI therapy is not achieving glycaemic targets.
In late onset type 1 diabetes, assuming the individual is otherwise cognitively and physically well, the management is no different. With the less abrupt onset there is often a prolonged ‘honeymoon’ phase after diagnosis when endogenous insulin production still provides a significant contribution to glycaemic control. In our unit we use this period to focus on prandial insulin adjustment and carbohydrate counting skills with the endogenous insulin providing the background cover. Injected background insulin is then introduced as soon as we notice a rise in fasting blood glucose outside the target range. This helps to embed early skills in carbohydrate counting and prandial insulin dose adjustment.
In elderly patients with cognitive impairment or physical disability that prevents them from self managing effectively, the management regimen has to be simplified, and this is often associated with overall glycaemic control that is less tight. Twice daily mixed insulin can be given, usually in fixed doses, and the mainstay of glycaemic control then becomes dietary regulation and restriction that can adversely affect quality of life. Research into the artificial pancreas, an insulin pump, which infuses insulin at a constantly varying rate in response to feedback from a subcutaneous continuous glucose monitor, is proceeding rapidly, but we are not there yet.
Complications of type 1 diabetes fall into two categories. These are firstly acute complications of insulin deficiency and insulin replacement; namely diabetic ketoacidosis (DKA) and severe hypoglycaemia (SH). The second category is endorgan complications that develop due to glucosemediated vascular damage, most notably in the eyes, kidneys, general circulation and extremities. Endovascular deterioration in type 1 diabetes also contributes to increased incidence of cardiovascular and cerebrovascular events. The mainstay of management is empowering and training people with type 1 diabetes to self-manage their condition optimally to minimise their risk of developing any of these complications. The barrier to optimal management is the mismatch between the freedom and spontaneity of a non-diabetic lifestyle compared with a life dominated by decisions on whether to eat more, eat less or change the insulin dose. Out-patient training courses are available; the gold standard recommended by NICE is DAFNE training (dose adjustment for normal eating), and people should have access to this training from 6-12 months after diagnosis.1
DAFNE training originates from a German insulin teaching and training programme devised by Professor Michael Berger and his wife Ingrid Mülhauser in the 1980s.2 DAFNE education has been available to patients in the UK since 2001 and is delivered by local diabetes teams who have been trained through the DAFNE NHS consortium. Courses are delivered in over 70 diabetes services across the UK; and in Australia, New Zealand and Kuwait. It involves a five-day training course for people with type 1 diabetes that can be delivered either Monday-Friday, or one day a week over five weeks.
There is a lot to learn, and anecdotal feedback suggests that older people prefer the five-week format with a slower pace of learning and chance to absorb and process new information before the next week’s lesson. There are eight people on each course and much of the benefit relates to participants learning from each other as well as from the educators. Although the NICE guidance recommends a DAFNE course within 6–12 months of diagnosis this depends on how rapidly beta cell failure is occurring, and may be better delayed in late onset type 1 diabetes until the patient is more fully dependent on exogenous insulin. Furthermore, there are legions of long-diagnosed adults with type 1 diabetes who gain tremendous benefit from a DAFNE course even if it was not available for them at the time of their diagnosis.
Participants use two different types of insulin injected on average five times daily: background intermediate acting insulin twice daily on waking and retiring, and quick acting insulin before eating carbohydrate (figure 1). Meals or snacks that do not contain carbohydrate generally do not require any quick acting insulin to be injected. Eating food containing carbohydrate requires a dose calculation, which relates to the quantity of carbohydrate and the personal insulin to carbohydrate ratio. Several models of blood glucose meters now have ‘bolus calculators’ within them to assist with dose calculation. Participants can therefore eat freely and flexibly without diabetes related restriction, and can adjust their daily routine to incorporate irregular mealtimes and exercise whilst maintaining good glycaemic control.
The DAFNE course provides evidence-based training in the use of algorithms for insulin dose adjustment during sickness, exercise, coping with the effects of alcohol and eating out.3 Ongoing research has shown huge savings for the NHS4 in terms of reduced emergency treatment costs from DKA and SH for people who have completed DAFNE training.5 Reports of benefits for participants in terms of quality of life, reduced depression and anxiety scores, and reduced severe hypoglycaemia continue to be published.6
Regular audit of UK DAFNE graduates (people with type 1 diabetes who have completed a DAFNE course) is performed annually showing overall improvement in HbA1c at 12 months, reduced severe hypoglycaemia, restoration of hypoglycaemia unawareness and increased proportion of graduates with HbA1c under 58mmol/mol (presented at DAFNE Collaborative meeting June 2016, data available on request). There is no upper age limit for participants on DAFNE—just a requirement for an open mind, willingness to learn new skills, and ability to understand some simple arithmetic with the help of a calculator if necessary. We looked specifically at our national database in relation to age of participant and how long they had diabetes before undertaking DAFNE. We confirmed that there was no link between duration of diabetes and deriving benefits from DAFNE—the oldest participant was 74 and had type 1 diabetes for 55 years.7
Comments from participants
Comments from participants on DAFNE courses are perhaps the most moving and convincing feedback. Here are just a few:
- “DAFNE has quite literally transformed my life —if only it had been available when I was first diagnosed”
- “DAFNE has given me my life back”
- “The course was hard work—I hadn’t been in a classroom for over 30 years—but it was honestly the most useful week I have ever spent in my life.”
Contact your hospital diabetes team to find out whether there is DAFNE course provision in your area. More patient testimonials at: www.dafne.uk.com
Dr Helen E Hopkinson, Consultant physician, Glasgow Chair, DAFNE UK Executive Board
Conflict of interest: I am paid 12 hours a month by Northumbria Healthcare Trust for work associated with chairing the Executive Board of DAFNE. This is an NHS consortium subject to NHS financial governance regulations and run on a not-for-profit model to support the delivery of DAFNE training to healthcare professionals and patients throughout the UK. Central DAFNE receives current sponsorship from Lilly and Abbott (and previously Novo Nordisk and Sanofi) to supplement some of the costs of educating healthcare professionals.
2. Mühlhauser I, Jorgens V, Berger M, et al. Bicentric evaluation of a teaching and treatment programme for type 1 (insulindependent) diabetic patients: improvement of metabolic control and other measures of diabetes care for up to 22 months. Diabetologia 1983; 25: 470–76
3. DAFNE Study Group. Training in flexible, intensive insulin management to enable dietary freedom in people with type 1 diabetes: dose adjustment for normal eating (DAFNE) randomised controlled trial. BMJ 2002; 325: 746–52 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC128375/pdf/746.pdf (last accessed 31/08/16)
4. NICE. Quality and Productivity: Proven Case Study. Improving the quality of care for patients with type 1 diabetes: dose adjustment for normal eating (DAFNE) 2013. Available at http://www.evidence.nhs.uk/qipp (type ‘DAFNE’ into the search tool)
5. Elliott J, Jacques RM, Kruger J, et al. Substantial reductions in the number of diabetic ketoacidosis and severe hypoglycaemia episodes requiring emergency treatment lead to reduced costs after structured education in adults with Type 1 diabetes. Diabetic Medicine 2014; 31(7): 847–53. http://onlinelibrary. wiley.com/doi/10.1111/dme.12441/epdf (last accessed 30/08/16)
6. Hopkins D, Lawrence I, Mansell P, et al. Improved biomedical and psychological outcomes 1 year after structured education in flexible insulin therapy for people with type 1 diabetes. Diabetes Care 2012 35: 1638–42 http://www.ncbi. nlm.nih.gov/pmc/articles/PMC3402270/pdf/1638.pdf (last accessed 30/08/16)