Severe Hypoglycemia Followed By Disturbances In Blood Glucose - Brief Article

Nutrition Research Newsletter, Feb, 2001

Extensive studies have repeatedly demonstrated that the maintenance of blood glucose (BG) levels approximating the normal range reduces long-term complications of diabetes. However, the same studies have also reported the adverse effects of intensive insulin therapy, the most acute of which is the increased risk for frequent severe hypoglycemia (SH). This condition can result in stupor, seizure, or unconsciousness that precludes self-treatment. The purpose of this recently published study was to investigate the relative short-term changes in the Low BG index (LBGI) and other BG parameters associated with episodes of SH.

The participants of the study included 85 men and women between 21-60 years with type 1 diabetes mellitus of at least 2-yr duration and insulin use since the time of diagnosis. Subjects had at least two documented SH episodes within the past year and routinely used SMBG devices for diabetes monitoring. The participants were instructed to use Lifescan One-Touch Profile memory meters that can store up to 250 BG readings together with the date and time of each reading. They used the meter three-five times per day and recorded in diaries any SH episodes with the exact date and time.

During the study a total of 75,495 SMBG readings were downloaded from the participants' memory meters, and 399 SH episodes were recorded in diaries. Eighty percent of the subjects experienced one or more episodes of SH. These subjects did not differ from those who did not experience SH in terms of any of their demographic characteristics. During the study, 20 subjects experienced a recurrent SH within 48 hours. Fifty-three sequences of two, and nine sequences of three recurrent SH episodes were observed. In general, 18% of all SH episodes were followed within 48 h by a recurrent SH. In the period 48 to 24 h before SH, the average BG level decreased, and the BG variance increased. In the 24 h immediately preceding SH, the average BG level dropped further, and the variance in BG continued to increase.

On the basis of LBGI the researchers identified subjects at low, moderate, and high risk of SH. They then designed an algorithm that predicted 50% of all SH episodes that occurred in the subject group. This algorithm could potentially be used to devise warnings of imminent SH after further research is conducted to enhance the specificity and predictive capability of the algorithm.

This study was successful in identifying BG disturbances accompanying episodes of SH and offers quantitative tools for anticipation of imminent SH on the basis of routine SMBG data. This methodology could assist patients with type 1 DM with improving glycemic control without increasing the risk of SH. The findings of this study also show that subjects at high risk for SH can be identified, and more than 50% of SH episodes can be anticipated from SMBG data and therefore potentially avoided.

M. Kovatchev, D. Cox, L. Ferhy, M. Straume, L. Gonder-Frederick, W. Clarke. Episodes of Severe Hypoglycemia in Type 1 Diabetes are Preceded and Followed within 48 Hours by Measurable Disturbances in Blood Glucose. J Clin Endorin and Metab 85(11):4287-4292 (Dec 2000) [Correspondence: Dr. Boris P. Kovatchev, University of Virginia Health System, Box 800137, Charlottsville, VA 22908].