High Variability of Glycated Hemoglobin Concentrations in Patients With IDDM Followed Over 9 years: What is the best index of long-term glycemic control?
- Baldev M Singh, MD, MRCP,
- Catherine McNamara, MRCP and
- Peter H Wise, PHD, FRCAP, FRCP
- Address correspondence and reprint requests to B.M. Singh, MD, MRCP, Wolverhampton Diabetes Centre, New Cross Hospital, Wolverhampton WV10 0QP, U.K.
Abstract
OBJECTIVE To determine variability of long-term glycemic control in patients with IDDM.
RESEARCH DESIGN AND METHODS A retrospective analysis of HbA1 among 122 IDDM patients followed over 9 years.
RESULTS Annual group mean HbA1 ranged from 8.4 to 9.3% with large standard deviations (1.7–2.0%), indicating marked variability among individuals. Fluctuations of more than ± 1% HbA1 occurred in 50% of the patients year to year, and over 9 years the minimum-maximum range was > 3 and > 5% HbA1 in 55 and 11% of patients, respectively. In any one year, 22–43% of patients had HbA1 < 8%, but over 9 years only 3.3% were consistently < 8%. Groups divided according to baseline HbA1 of < 8, 8–10, and > 10% were significantly separated over 9 years by frequency distribution analysis of individual mean HbA1 but were indistinguishable when analyzed by individual HbA1 interquartile range (measure of variability).
CONCLUSIONS High variability of long-term glycemic control is a marked feature of IDDM, the extent of which may be relevant to microvascular risk.
- Received May 9, 1996.
- Revision received October 8, 1996.
- Accepted October 8, 1996.
- Copyright © 1997 by the American Diabetes Association
