This is the standard intensive-insulin regimen by which all others in type 1 diabetes are judged. The principle is simple: to provide basal (background) insulin, especially during the night, using a long-acting insulin, and bolus doses of short-acting insulin with meals (Fig. 4.2). Its utility was confirmed in the DCCT (reported 1993) where mean HbA1c values differed very little from those using insulin pumps (7.0% vs. 6.8%, 53 vs. 51 mmol/mol). Interestingly, children and adolescents have lower rates of severe hypoglycemia with MDI than do adults, though this problem increases again in older adults with very long duration type 1 diabetes (> 30 years).
MDI is physiologically sound, but practical implementation can be complex and requires the following.
- Frequent home blood glucose monitoring.
- An ability to adjust prandial doses in relation to carbohydrate intake, blood glucose levels, prior and anticipated physical activity, previous experience of hypoglycemia, mental stress and menstruation. This requires detailed continuing education, preferably with specific programmes, for example DAFNE (Dose Adjustment for Normal Eating, UK and Australia).
- Frequent contact with a team experienced in intensive insulin treatment.
- Using the simplest, most portable, and robust physical devices for self-testing and injection.
- Recognizing the marked day-to-day and interindividual variation of insulin action, and that the use of MDI per se does not confer automatic glycemic advantage. For example, in 2005 an international survey of young people comparing insulin regimens found that patients using twice-daily free-mixed soluble and isophane insulin, a regimen relatively little used these days, had a significantly lower mean HbA1c (7.9%, 63 mmol/mol) than those using MDI or continuous subcutaneous insulin infusion (CSII) (8.2% and 8.1%, 66 and 65 mmol/mol, respectively) – a good demonstration that the insulin regimen used is less important than the expertise and interest of the diabetes team.
Biphasic (fixed-ratio) Mixtures
Usually regarded as inadequate treatment in type 1 diabetes, these are used in about 7% of young people across Europe. Glycemic control is worse compared with MDI treatment (mean HbA1c 8.6% vs. 8.2%, 70 vs. 66 mmol/mol), but there is no difference in hypoglycemia rates between human and analogue biphasic preparations. However, analogue mixtures given with meals, as opposed to before meals, are more convenient. Control to target levels is sometimes but not commonly seen, but the regimen may be preferable to MDI where the lunchtime dose (and possibly others) is missed. The 50/50 high-mix preparations are no better than the standard 30/70 mixtures, at least in type 1 diabetes. A variant used in young people, avoiding the often ignored lunchtime injection, is a biphasic mixture with breakfast, soluble or rapid-acting analogue with the evening meal, and a standard long-acting insulin at bedtime, but control is no better than with twice-daily biphasic mixtures, and three different insulins are needed, which probably impedes adherence.
For more information and to purchase this book, just follow this link:
David Levy, MD, FRCP, Consultant Physician, Gillian Hanson Centre, Whipps Cross University Hospital; Honorary Senior Lecturer
Queen Mary University of London London, UK
This edition first published 2011, © 2011 by David Levy. 1st edition 1998 (Greenwich Medical Media/Cambridge University Press) 2nd edition 2006 (Altman Publications)