1. Many GPs are wary of initiating insulin, for valid reasons. The very act of starting insulin can feel like an admission of failure to control the disease. But the reality is that our efforts to get A1c down to target must be seen in the context of a progressive disease, in which A1c has a natural tendency to climb each year. Eventually the time comes when insulin should no longer be put off.
2. The classic, and all too common, scenario is the patient on metformin and another oral drug whose A1c won’t come down below 8.0. No single additional oral drug will bring the level below 6.5, so even a 3-drug regimen would leave the patient with uncontrolled glycemia. It’s time for insulin. And according to current Canadian guidelines, A1c over 9.0 is an indication for insulin even if oral drugs haven’t been tried yet.
3. There’s been much debate over the best starting insulin regimen, but this has been largely resolved by the robust Treating to Target in Type 2 diabetes (4-T) trial. For patients whose A1c is under 8.0 on oral antihyperglycemics, basal insulin at bedtime is the first choice. Glycemic control is less spectacular than with biphasic or prandial insulin, but weight gain is less too, and there’s less risk of hypoglycemia.
4. While intermediate-acting NPH insulin can be used for bedtime basal insulin, there may be less risk of nocturnal hypoglycemia with the long-acting insulin analogues, detemir and glargine. Their main downside is cost.
5. Doses will tend to go up over time, and more complex regimes will be needed. Biphasic dosing is simpler than prandial, with less risk of hypoglycemia and weight gain. Biphasic can bring greater A1c reductions, but daily peak glucose levels will be lower with prandial dosing.
6. Bedtime dosing avoids the necessity of carrying an insulin kit, and of course minimizes the number of injections. But in fact today’s needles make insulin injection almost painless, certainly easier than finger-stick glucose measurements. Inhaled insulin is approved in Canada, but will never be an answer for needle phobia. It’s only useful for short-acting roles, has higher hypoglycemia risk, is very expensive and dosing is tricky. It may also harm lung function.
7. Insulin pumps are most useful in type 1 diabetes. They are not an answer for the disorganized patient, because they still require users to monitor glucose and input data. Work proceeds on a new generation of pumps, however, that will measure glucose themselves and adjust dose accordingly. That really will be a step forward.
8. Suggested initial doses and titration regimes can be found in appendix 3 of the Canadian guidelines (www.diabetes.ca/files/cpg2008/cpg-2008.pdf). Titrate up fairly quickly, because patients starting insulin want to see results. Titrate more slowly in older and slimmer patients. Don’t stop oral antihyperglycemic treatments when starting insulin.
9. Hypoglycemia is less common in type 2 patients taking insulin than in type 1. Five events a year was the average rate in the 4-T trial, but almost all of these were mild cases of autonomic symptoms, self-treated with glucose. Many of the severe events seen in trials occurred in patients who were concurrently taking sulphonylureas, which are known for causing hypos.
10. If you have a poorly-controlled patient who isn’t yet ready to take insulin, consider adding pioglitazone (but not in patients with low BMD). It alleviates fatty liver, a common problem in diabetes. This should make insulin therapy more effective if/when it becomes unavoidable.
