Effect of Glycemic Variability on Autonomic Tone in Hospitalized Patients With Type 2 Diabetes
Status:
Completed
Trial end date:
2012-12-01
Target enrollment:
Participant gender:
Summary
Glycemic variability has been associated with mortality in hospitalized patients with
hyperglycemia. However, it is unknown how modulation of glycemic variability would impact
outcomes. One possibility is that glycemic variability could impact autonomic tone. In
particular, heart rate variability (HRV) measurement is a sensitive marker for measuring
autonomic tone, and aberrations in HRV have been associated with mortality. The current
randomized pilot study will compare the effects of continuous intravenous (IV) insulin and
subcutaneous basal bolus insulin on glycemic variability and autonomic tone in hospitalized
non-critically ill patients with diabetes. Non-critically ill patients who are hyperglycemic
or are requiring at least 20 units of insulin per day will be included. Patients with
conditions that preclude accurate HRV readings (such as atrial fibrillation or paced rhythms)
will be excluded. Patients randomized to intravenous insulin will receive the therapy for 24
hours according to our standard hospital guideline. Patients randomized to subcutaneous (SQ)
insulin will receive basal bolus therapy using insulin analogues. All therapies will begin
between 8 and 10 AM. Patients will undergo repeated heart rate variability recordings during
the 24 hour period. Blood draws will be collected at baseline and at 24 hours for measurement
of catecholamines, insulin, and c-peptide. Glycemic variability will be measured using a
continuous subcutaneous glucose monitor and reported as coefficient of variation. The primary
outcome measure is low frequency-to-high frequency power spectrum ratio of heart rate
variability.
1. Glycemic variability is associated with unfavorable changes in autonomic tone, as
assessed by low frequency (LF)/high frequency (HF) HRV ratio, independent of changes in
overall glycemia.
2. Short-term increases in glycemic variability, followed by more prolonged glycemic
stability are observed in generalized hospitalized patients treated with intravenous
insulin compared to standardized basal bolus therapy. LF/HF HRV differs among subjects
receiving intravenous compared to subcutaneous insulin.
3. Glycemic variability differs among subjects receiving intravenous compared to
subcutaneous insulin