Insulin Therapy in Type 2 Diabetes

Type 2 diabetes mellitus is characterized by insulin resistance and progressive beta cell failure. Typical therapy usually includes diet and exercise to effect weight loss, and oral hypoglycemic agents.

Until recently it was felt that a stepwise approach to treatment, taking 8-16 month to achieve control was acceptable. It is now felt that because short-term hyperglycemia can lead to vascular changes, and because patients have often been hyperglycemic for some time prior to diagnosis, aggressive therapy is warranted to bring the sugar into control.

One of the new recommendations is that combination therapy using sub-maximal doses of oral hypoglycemics be prescribed, rather that pushing a single agent to the maximum dose. This is because the first part of the dose response curve is the steepest for these agents and as you increase the dose you get "less bang for your buck".

It may also be necessary to combine oral hypoglycemics with Insulin. This combination has the advantage of controlling the hyperglycemia with less weight gain than seen by using insulin alone. It also reduces the risk of hypoglycemia and allows for the use of less insulin. Patients who are reluctant to consider regular daily insulin are also more likely to agree to "trying a little insulin at night", to control the sugar.

Other roles for insulin in Type 2 diabetics include:

• Initial therapy, especially in the presence of marked hyperglycemia (A1C ≥9.0%)
• Temporarily during illness, pregnancy, stress, a medical procedure or surgery.

Once you have decided to add insulin to the drug regimen, there are several options available to you. You must, however, tailor the treatment to the individual patientŐs needs. The CDA 2003 Guidelines, Appendix 9 give the following 3 examples:

Appendix 9: Insulin Initiation in People With Type 2 Diabetes

The sample insulin regimens described here are examples only. Other options are possible. All people starting insulin should be counselled about the recognition and prevention of hypoglycemia.

Option A: Single bedtime injection of insulin added to oral antihyperglycemic agents (0.1-0.2 units/kg)

100% as basal insulin (e.g. NPH, N, glargine) at bedtime

Option B: 2 insulin injections per day, premixed dose (e.g. 30170, 50150) (0.5 units/kg)

2/3 of total dose in the morning

1/3 of total dose with evening meal

Option C: Intensive insulin regimen (0.5 units/kg)

40% of total dose at bedtime (e.g. NPH, N, glargine) at bedtime

20% of total dose at each meal (e.g. rapid-acting insulin analogue, fast-acting insulin)

- John Hickey

Thanks to Dr. Stewart Harris for reviewing the draft copy of this article. Dr. Harris is Associate Professor at the University of Western Ontario, London, Ontario with Joint Appointments in the Department of Family Medicine, Department of Epidemiology and Biostatistics and the Division of Endocrinology and Metabolism.

Reference:

Canadian Diabetes Association 2003 Clinical Practice Guidelines.