Source: Porcellati F, et al. Diabetes Care 2015;38:503-512.

The “indication” labeling for insulin glargine (Lantus) simply says, “Administer subcutaneously once daily at any time of day, but at the same time every day.” Some patients and clinicians prefer morning administration, some prefer evenings, and some even prefer twice-daily injections, although the latter is clearly off-label. The important question is, then, does it make any difference when you give insulin glargine, or is it just personal preference?

The pharmacokinetics and pharmacodynamics of insulin glargine were studied in 10 subjects with type 2 diabetes who had already been receiving insulin glargine as part of their therapeutic regimen. Subjects were randomized in a crossover design to dose insulin glargine at either 10 a.m. or 10 p.m., with dose optimization attained during a 2-week period to achieve fasting blood glucose (FBG) ≤ 100 mg/dL without experiencing nocturnal hypoglycemia (glucose < 72 mg/dL).

Several interesting results were noted. First, the actual dose needed for optimization of FBG was slightly greater when glargine was administered at 10 a.m. than 10 p.m. Second, morning administration of glargine had less glucagon-suppression effect in the second half of the 24-hr cycle than evening administration had in the second half of its 24-hr cycle. Evening administration also limited lipolysis more than morning, resulting in lower levels of plasma fatty acids.

The differences between morning and evening glargine administration demonstrated here are quite modest, but do suggest that overall, evening administration may be superior in reference to some dysregulations seen in type 2 diabetes, such as glucagon and fatty acids.