Hypoglycaemia: prior blood sugars predicted severe hypoglycaemia

Clinical bottom line (level 1b)

  1. Patients with IDDM who had an average of blood sugar values analysed predicted future episodes of severe hypoglycaemia
  2. In patients with IDDM, a past history of severe hypoglycaemia and the calculated index of blood sugars were independent predictors of further episodes of severe hypoglycaemia
Kovatchev et al: Diabetes Care 1998; 21 (11): 1870-1875
Expires August 2003

The study

Prospective cohort study with objective outcomes, adjusted for confounding factors, validated in an independent set of patients.

Setting: outpatients with IDDM in two clinics in the USA

100 patients (aged mean 35y, 58% male) IDDM for at least 2y, on insulin and routinely performing blood glucose monitoring
calculated 'Low-blood glucose index'

index formed by averaging a log transformation of glucose measurements

96% overall followed for 6 months
Outcomes studied:
  • tBG = 1.794*[(log(BG))^1.026 - 1.861]; risk = 10*(tBG)^2 if tBG<0 otherwise risk = 0; LBGI = mean of risk values OVER 4 WEEKS

The evidence


  • Patients were classified into:
    • low risk- low blood glucose index <2.5
    • moderate risk- low blood glucose index 2.5 to 5.0
    • high risk- low blood glucose index >5.0
  • Severe hypoglycaemic episodes reported per patient:
    • low risk- 0.4
    • moderate risk- 2.3
    • high risk- 5.2
  • The frequency of future severe hypoglycaemic episodes was predicted by the low blood glucose index and history of severe hypoglycaemia (no odds ratios were given).

Comments

  1. Study is a validation of work previously undertaken, but with the same clinic staff.
  2. Complexity of score may be difficult to use in clinical practice

Citation

  1. Kovatchev BP, Young-Hyman D, Cox DJ, et al: Assessment of risk for severe hypoglycaemia among adults with IDDM. Diabetes Care 1998; 21 (11): 1870-1875
Contributor: Bob Phillips and Clare Wotton, August 1999
Reviewer:

Clinical Question.
Patient patients with IDDM
Intervention or Exposure an index of blood sugar readings
Outcome predict risk of episodes of severe hypoglycaemia