Can a Patient Start Mixtard at Night?
Yes, a patient with diabetes can start Mixtard (premixed insulin) at night, but this is generally NOT the preferred approach according to current evidence-based guidelines. Modern diabetes management strongly favors basal-bolus regimens or basal insulin alone over premixed insulins, particularly in hospital settings and for optimal glycemic control.
Why Premixed Insulin at Night Is Not Ideal
Premixed insulins like Mixtard are explicitly not recommended in hospital settings due to unacceptably high rates of iatrogenic hypoglycemia compared to basal-bolus regimens 1.
Randomized trials demonstrate that basal-bolus therapy provides better glycemic control with reduced hospital complications compared to premixed insulin regimens, which have significantly increased hypoglycemia rates 1.
The fixed ratio of rapid-acting and intermediate-acting insulin in premixed formulations (like Mixtard's 30% regular/70% NPH) does not allow for independent adjustment of basal versus prandial coverage, leading to suboptimal control 1.
When Premixed Insulin Might Be Considered
For patients with type 2 diabetes who require simple regimens and have predictable meal patterns, twice-daily premixed insulin may be used, though this is considered a less optimal approach 2.
In resource-limited settings or for patients unable to manage multiple daily injections, premixed insulin two or three times daily may be acceptable 2.
Preferred Alternative Approaches
For Type 2 Diabetes Patients
Start with basal insulin alone (such as insulin glargine or detemir) at 10 units once daily or 0.1-0.2 units/kg body weight, administered at the same time each day, preferably at bedtime 1.
Continue metformin unless contraindicated, as the combination provides superior glycemic control with reduced insulin requirements and less weight gain 1, 2.
Titrate basal insulin by 2-4 units every 3 days until fasting blood glucose reaches 80-130 mg/dL 1.
For Type 1 Diabetes Patients
Multiple daily injections are required from diagnosis, typically with short-acting or rapid-acting insulin analogue given 0-15 minutes before meals together with one or more daily injections of intermediate or long-acting insulin 2.
Total daily insulin requirements typically range from 0.4 to 1.0 units/kg/day, with approximately 50% as basal insulin and 50% as prandial insulin 1.
Specific Concerns About Nighttime Mixtard Administration
The intermediate-acting (NPH) component in Mixtard peaks at 4-6 hours after administration, which would occur in the middle of the night if given at bedtime, significantly increasing nocturnal hypoglycemia risk 3.
Nocturnal hypoglycemia is already a persistent challenge, with the incidence peaking between midnight and 6:00 AM, and adding a peaking insulin at night exacerbates this risk 4, 5.
Long-acting basal analogs (glargine, detemir, degludec) reduce the risk of nocturnal hypoglycemia compared to NPH-containing insulins like Mixtard 4.
Critical Pitfalls to Avoid
Never use premixed insulin in hospitalized patients due to the significantly increased hypoglycemia rates compared to basal-bolus regimens 1.
Do not give rapid-acting or short-acting insulin at bedtime to avoid nocturnal hypoglycemia, which is precisely what the regular insulin component of Mixtard would do 1.
Avoid fixed-ratio premixed insulins when patients need flexible dosing based on carbohydrate intake and blood glucose patterns 1.
Recommended Clinical Approach
If a patient requires insulin initiation:
Start with basal insulin alone (glargine, detemir, or degludec) at bedtime, 10 units or 0.1-0.2 units/kg/day 1.
Titrate aggressively by 2-4 units every 3 days based on fasting glucose patterns 1.
Add prandial insulin only when needed: when basal insulin exceeds 0.5 units/kg/day or when fasting glucose is controlled but HbA1c remains elevated after 3-6 months 1.
Monitor for nocturnal hypoglycemia with fasting blood glucose checks and consider continuous glucose monitoring if available 4.
If a patient is already on Mixtard and experiencing issues:
Transition to a basal-bolus regimen by calculating the total daily dose from Mixtard, giving 50% as basal insulin once daily and 50% as prandial insulin divided among three meals 1.
Reduce the calculated total daily dose by 20% in high-risk patients (elderly >65 years, renal failure, poor oral intake) to prevent hypoglycemia 1.