Ensuring Control in Type 2 Diabetes

Summarized by Robert W. Griffith, MD
March 22, 2007

Summary

A study shows that poor adherence to antidiabetic drug therapy is largely responsible for worsened control of type 2 diabetes in indigent people.

Introduction

In diabetes (type 1 or type 2), strict metabolic control means a better outlook - a reduced likelihood of complications that usually shorten lifespan. So it's beneficial to maintain optimal blood sugar levels, whether it's by appropriate lifestyle (diet, exercise, etc) or by taking medication. Assuming the best medical treatment has been prescribed, there remains the real possibility of a 'gap' in optimal care represented by poor adherence to medication.

While patient education about the disease and the way it is managed is largely the responsibility of the health provider, compliance with acquiring and taking medication may be dependent on the patient's circumstances. A study published in 2002 in the journal Diabetes Care has analyzed the issue of medication adherence in diabetics under varying conditions. Here's what the University of Virginia researchers reported.

What was done

Rural central Virginia contains several low-income population areas. One of these provided a sample of 810 indigent type 2 diabetics who were being treated with oral medications. Over 90% of them were receiving a 50% to 99% subsidy of their prescription drug costs (the amount of subsidy was based on income). For inclusion in the analysis they had to be taking at least one oral antidiabetic drug (a sulfonylurea, metformin, an alpha-glucosidase inhibitor, or a thiazolidinedione), and be either Caucasian or African-American.

Adherence to a medication regimen (sometimes called compliance) is defined as the extent to which patients take their drugs as prescribed by their physician. Prescription refill data from the University of Virginia pharmacy were used to obtain this information. Adherence is usually reported as the percentage of the prescribed doses of a medication actually taken over a given period.

The patients all had at least one HbA1c blood level done during the study.¹ The degree of control of their diabetes was based on the most recent HbA1c value during the study period, with improvement in control defined as the difference between the first and most recent HbA1c value.

What was found

The average age of the participants was 59; 42% were African-American, and 61% were women. As many as 61% had family income below the federal poverty line and 92% had income less than twice the poverty line. Insulin was being taken by 30% of the patients. The average HbA1c level overall was 8.1%, with a decrease of 0.5% during the study.

Better metabolic control was associated with increasing age, white race (vs. African-American), and less intense drug therapy (fewer meds, no insulin). It was also associated with greater medical adherence, after allowance was made for these other factors. Thus for every 10% increase in drug adherence, the HbA1c level decreased by 0.16%. This was a highly significant result from the statistical point of view, i.e. it could not have occurred by chance alone.

As indicated, the degree of diabetic control for African-Americans was significantly lower than for whites - their HbA1c was, on average, 0.29% higher than that of whites - and their adherence was less, too. Interestingly, there was no association between diabetic control and gender, income, and continuity of care.

What these findings mean

This analysis shows that poor drug adherence is largely responsible for worsened metabolic control of diabetes in an indigent population. The authors of the study point out that the findings stand in contrast to several previously published reports; however, these studies were not specified as being done in poor populations. Other studies, though small, support the findings in this study.

The results found here are not entirely surprising. But they do show that income was not a factor - although it shouldn't have been, anyway, as the medications were largely subsidized, according to ability-to-pay. We must look to other reasons for poor compliance. The chief of these is probably lack of adequate patient education in how to self-manage their condition. Physicians, other health providers, and the patients themselves share responsibility for this. Only by improving patient knowledge can one hope to improve their adherence to drugs once the cost factor is removed. The goal is to achieve a high degree of self-management for as many patients as possible.

Source

• The association between diabetes metabolic control and drug adherence in an indigent population. JM. Schectman , MM. Nadkarni, JD. Voss, Diabetes Care , 2002, vol. 25, pp. 1015--1021

Footnotes
1. HbA1c is shorthand for a type of hemoglobin, the oxygen-carrying element in red blood cells. (Hb stands for hemoglobin, and A1c is the designation of the subtype.) It's important because glucose binds to HbA1c and is only released very slowly, so that the HbA1c represents the average blood glucose level over the previous 4 weeks. It's a better measure of the degree of diabetes than isolated blood sugar determinations.

Related Links
Some Diabetics Are Not Taking Their Medication
Non-compliance of Diabetics in Canada
Diabetes Self-Management Centre, Ontario