Type 1 Diabetes Mellitus Contemporary Management
Original title: Contemporary Management of Type 1 Diabetes Mellitus
By: Dr Daphne Gardner, Associate Consultant, Department of Endocrinology, Singapore General Hospital
Type 1 diabetes (T1DM) is characterised by absolute insulin deficiency of insulin secretion, predisposing individuals to ketoacidosis and necessitating insulin replacement.
Worldwide, the incidence of T1DM has been increasing, particularly in children under the age of 5 years1. In general, T1DM comprises around 5-10% of the total diabetes prevalence. In Singapore, the incidence of childhood type 1 diabetes mellitus in Singapore is relatively low compared with developed countries at 2.46 per 100,000 children aged 1-12 years2. Yet, it remains the predominant form of diabetes affecting children in Singapore.
Miss DH is a 28 year-old lady who was diagnosed with T1DM at the age of seven years. In 2003 (age 20 years old), she started experiencing more frequent episodes of hypoglycaemia. This culminated in an admission with severe hypoglycaemia, having lost consciousness at home. Following this, she was converted from the older human insulins to analogue insulins. Despite this, she continued to document frequent hypoglycaemia, mostly between or before meal times, with erratic high readings after mealtimes. There appeared to be little predictability or pattern with her readings and she continued to be unaware of her hypoglycaemia. There were no other symptoms suggestive of gastroparesis and there was some lipohypertrophy on her abdomen but despite rotating the injection sites, this erratic pattern continued. HbA1c throughout the years appeared well (perhaps too tightly) controlled, ranging from 5.7-7.5%. However, HbA1c clearly describes just one aspect of glucose control ie the average. It does not illustrate the fluctuation of glucose around this mean glucose level.
demonstrates the interstitial glucose profile of this patient over 24 hours, using a continuous glucose monitoring sensor device. The large variation in glucose range from hypoglycaemia to marked hyperglycaemia (2.2-20 mmol/l) is typical of an individual with T1DM. ‘Brittle diabetes’ is an ill-defined term previously used to describe those with diabetes which is difficult to control, or with wide fluctuations in glucose levels, such that these individuals are deemed to be often at the threshold of either hypoglycaemia or diabetes ketoacidosis. However, it is now clear that most individuals with T1DM experience glucose profiles like these, even when they are on basalbolus insulin regimens which aim to mimic physiological insulin replacement.
Where is the missing link? Carbohydrate is the main macronutrient that results in post-prandial glucose increase and should therefore be the major determinant of bolus insulin doses. In contrast, prescriptive doses of bolus insulin (e.g. 6 units thrice daily) do not take into account varying amounts of carbohydrate intake, with the resultant large variations in glucose level following a meal. Those who are on fixed insulin regimens are expected to maintain fixed carbohydrate intake on a day-to-day basis with respect to time and amount3. Unsurprisingly, few individuals adhere to this, and no account is taken of situations like snacking, physical activity or alcohol. Hence, daily management of glucose in T1DM needs to involve education of the patient in selfmanagement and carbohydrate counting.
This may be achieved through the Dose Adjustment For Normal Eating (DAFNE) programme which originated from Germany. Longer-term studies have supported the efficacy of such a programme, showing improved, sustained glycaemic control (HbA1c) without increased hypoglycaemia and an improved quality of life4. Currently, Singapore General Hospital (SGH) is the only centre in Asia that runs such a programme. The sgDAFNE team consists of a Dietitian, Diabetes Nurse Educator and a Physician. Together, a comprehensive curriculum is delivered to T1DM participants, aimed at equipping individuals with knowledge in advanced carbohydrate counting, analysing glucose levels and making informed decisions on bolus/prandial insulin doses and managing situations like eating out, snacking and physical activity.
The importance of education in self-management is highlighted using an example of the treatment of hypoglycaemia (shown in figure 2) from the same patient after undergoing the DAFNE programme. In figure 2, bedtime hypoglycaemia occurred at 0015hrs (capillary glucose or CPG level of 2.4 mmol/l). In general, hypoglycaemia should be treated with 15-20g of quick-acting carbohydrates and glucose re-checked 15 minutes later to ensure adequacy of treatment. In this case, the patient consumed 18g of fruit juice and CPG re-checked 15 minutes later was 5.3 mmol/l. A further 14g of crackers (longer-acting carbohydrates) was consumed as there was going to be a prolonged period before the next meal intake and basal insulin was already on board. Figure 2
shows that following this treatment, glucose levels remained at a safe and good level of 7 mmol/l till the following morning.