Current issues of ACP Journal Club are published in Annals of Internal Medicine


Quality Improvement

Regular monitoring led to improvement in metabolic control and fewer hospitalizations in patients with IDDM

ACP J Club. 1991 Jan-Feb;114:29. doi:10.7326/ACPJC-1991-114-1-029


Source Citation

Larsen ML, Horder M, Mogensen EF. Effect of long-term monitoring of glycosylated hemoglobin levels in insulin-dependent diabetes mellitus. N Engl J Med. 1990;323:1021-5.


Abstract

Objective

To determine whether metabolic control improves in patients with insulin-dependent diabetes mellitus (IDDM) when their physicians are provided with regularly monitored hemoglobin A1c levels.

Design

1-year randomized, unblinded trial.

Setting

An outpatient clinic of a university hospital in Denmark, that provides care to approximately 700 patients with IDDM.

Patients

Patients were eligible if they had IDDM diagnosed before age 30, were dependent on exogenous insulin, and had a propensity to ketosis. The 240 consecutive eligible patients were all less than age 60 years, had been followed at the clinic for at least 2 years, and had never had a hemoglobin A1c measurement.

Intervention

240 patients had hemoglobin A1c that was assessed regularly, and results were either disclosed (monitored) or not disclosed (control) to the treatment team responsible for maintaining metabolic control. Blood and urine glucose measurements were available to caregivers for both groups. Data were analyzed for 107 patients in the control group and 115 patients in the monitored group.

Main outcome measures

Glycemic control was assessed as good (HgbA1c < 8%), acceptable (8% ≤ HgbA1c ≤ 10%), or poor (HgbA1c > 10%). Hospital admissions were monitored for both groups.

Main results

18 patients (7.5%) were lost to follow-up (assigned study group not stated). At 1 year, HgbA1c decreased from 10.1% to 9.5% in the monitored group compared with no change in the control group (P < 0.005). The decrease could be largely attributed to improvement in glycemic control in the poorly controlled group (baseline HgbA1c > 10%) whose HgbA1c dropped from 11.6% to 10.0%. The proportion in the monitored group with poor glycemic control declined from 46% at baseline to 30% at 1 year, compared with an increase in the proportion of poorly controlled nonmonitored patients from 45% at baseline to 50% at 1 year (P < 0.01). 36 of 115 monitored patients compared with 17 of 107 control patients had additional clinic visits (31% vs 16%, P < 0.05), {this absolute risk difference of 15% means that 1 additional clinic visit occurred for every 6 patients who received regular HgbA1c monitoring, 95% CI 4 to 23; the relative risk increase was 97%, CI 19% to 230%}*. Hospitalization for hypoglycemic or hyperglycemic episodes was less frequent in monitored patients (12 of 115) compared with controls (23 of 107) {10% vs 21%, P < 0.05. This absolute risk reduction of 11% means that 9 patients would need to be treated with HgbA1c monitoring (compared with control) to prevent 1 additional hospitalization, CI 5 to 67; the relative risk reduction was 51%, CI 9% to 74%}.*

Conclusions

In patients with IDDM who are followed with routine blood and urine glucose measurements, the addition of regular monitoring of hemoglobin A1c led to changes in diabetes treatment, improvement of metabolic control, and fewer hospitalizations that were prompted by poorly controlled glucose levels.

Source of funding: Not stated.

Address for article reprint: Dr. M. L. Larsen, Department of Clinical Chemistry, Odense University Hospital, DK-5000 Odense C, Denmark.

*Numbers calculated from data in article.


Commentary

This study provides convincing empiric support for the American Diabetes Association guidelines (1) for hemoglobin A1c monitoring for the management of diabetes mellitus. Even if lingering doubts remain about the value of "tight control," the reduction in hospitalization for hyperglycemia or hypoglycemia among those who were monitored justifies the routine use of monitoring.

Hemoglobin A1c monitoring is not a substitute for blood sugar assessments because insulin dosage must be adjusted according to the latter. It is possible that HgbA1c monitoring is needed less frequently, say, once a year, for patients whose blood sugars and HgbA1c levels indicate good control, given that this group did not improve with HgbA1c monitoring in the study. A small proportion of patients with diabetes will have satisfactory blood glucose levels and unexpectedly high HgbA1c levels, indicating poor glycemic control. It is unclear whether the results of this study apply to this challenging group. For patients with high blood sugars and high HgbA1c, the recommendation for HgbA1c determination at each clinic visit seems warranted. Alternatively, similar results may be obtained from more intensive home glucose monitoring.

Tom Wachtel, MD
Rhode Island HospitalProvidence, Rhode Island, USA


Reference

1. Standards of medical care for patients with diabetes mellitus. Diabetes Care. 1989;5:365-8.