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Glycemic control poorer with postprandial vs. preprandial insulin dosing
Children and adults who dose their bolus insulin after a meal have a higher HbA1c and require a larger insulin dose compared with those who dose their bolus insulin before eating, according to findings published in Endocrine Practice.
Anne L. Peters, MD, professor of clinical medicine at Keck School of Medicine at the University of Southern California, and colleagues evaluated data from the T1D Exchange Registry on 21,533 people with type 1 diabetes to determine the characteristics of participants who dose postprandial bolus insulin (32%) and preprandial (68%). Preprandial dosing was classified as “immediately before” or “several minutes before meal” and postprandial dosing was classified as “during meal” or “after meal.” Overall, 12,450 participants were younger than 18 years. Rapid-acting insulin was used by 99% of participants.
Children were divided into three age groups: 1 to 5 years, 6 to 11 years and 12 to 17 years. Adults were also divided into three age groups: 18 to 29 years, 30 to 64 years and 65 years and older.
Among children, HbA1c was higher in the postprandial group (8.69%) compared with the preprandial group (8.44%). The postprandial group undertook fewer self-monitoring blood glucose tests per day (5.7 tests per day) compared with the preprandial group (6.15 tests per day). The postprandial group required a modest but significantly higher insulin dose compared with the preprandial group among those in the age groups 6 to 11 years (1.05 IU/kg vs. I IU/kg) and 12 to 17 years (1.31 IU/kg vs. 1.16 IU/kg). Among children aged 1 to 5 years, the proportion of insulin pump users was significantly higher in the preprandial group (39%) compared with the postprandial group (24%). Among children aged 12 to 17 years, the proportion of insulin pump users was significantly higher in the postprandial (60%) compared with the preprandial group (47%).
Among participants aged 6 to 11 years, history of severe hypoglycemia was significantly more prevalent in the postprandial group (6%) compared with the preprandial group (4%). The postprandial group had a higher prevalence of diabetic ketoacidosis (12%) compared with the preprandial group (5%) in participants aged 1 to 5 years.
Among adults, HbA1c was lower in the preprandial group (7.81%) compared with the postprandial group (8.25%). The postprandial group undertook fewer SMBG tests per day (4.45 tests per day) compared with the preprandial group (5.31 tests per day). The postprandial group required a higher total daily insulin dose compared with the preprandial group in participants aged 18 to 29 years (1.15 IU/kg vs. 1.04 IU/kg). More participants in the postprandial group used insulin pumps (63%) compared with the preprandial group (56%).
There was no difference in prevalence of history of hypoglycemia or diabetic ketoacidosis between the two groups.
“This study is limited by being a retrospective analysis of patient self-report of insulin use, and there are many, often valid reasons why patients may choose to give insulin after eating,” Peters told Endocrine Today. “For instance, people (older and younger) who may not be able to determine how much they will eat in advance of a meal may be better off giving insulin after they eat than before. However, the use of CGM has made it clear to many patients and providers that postprandial blood glucose levels are often uncontrolled and giving insulin in advance of eating is the best option for controlling the after eating glucose rise. This study supports this notion and suggests we should discuss with patients the timing of their insulin injections to optimize their control.” – by Amber Cox
For more information:
Anne L. Peters, MD, can be reached at annepete@med.usc.edu.
Disclosures: Peters reports various financial ties with Abbott, Becton Dickinson, Bigfoot, Boehringer Ingelheim, Dexcom, Eli Lilly and Company, Janssen, Lexicon, Livongo, Medscape, Merck, Novo Nordisk, Omada Health, Sanofi and Science 37. Please see the study for all other authors’ relevant financial disclosures.
Perspective
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Even though the pharmacokinetics of rapid-acting insulin analogues show a faster onset of action and peak more quickly than regular insulin, these analogue insulins work best when given with meals, not after. In fact, one of my favorite diabetes educators, Ellen Davis, RN, CDE, uses the acronym TIE (Test, give your Insulin, and Eat) to teach how and when to give insulin. With the advent of CGM, we have found that in some patients, rapid-acting insulin needs to be given 15 to 30 minutes before a meal to match carbohydrate digestion.
We've offered postprandial insulin injection in certain circumstances, such as patients with gastroparesis, patients who aren't sure what they are going to eat or patients who forget to take their insulin. However, this study by Peters and colleagues reveals that patients who take insulin postprandially have worse control and poorer diabetes self-management skills as evidenced by decreased testing frequency. It is unclear whether it is taking the insulin postprandially or the self-management skills of the patient. I suspect it's both. Giving insulin postprandially causes peak insulin not to match peak carbohydrate digestion. In addition, if patients dose insulin based on postprandial glucose, this is reactive. We prefer patients to be proactive with insulin dosing (ie, checking glucose prior to eating, dosing insulin based on planned carbohydrate intake and preprandial glucose.) It is interesting that younger patients were more likely to dose insulin postprandially. This might be a carry over for when parents were not sure how much a child might eat and dosed after eating to count the carbohydrates actually consumed. It is worth reminding providers of diabetes patients to confirm that they are dosing insulin preprandially, to share with them that postprandial dosing is associated with worse control. This is particularly important when patients transfer from their pediatric provider to their adult provider. For patients with dementia, for whom food intake cannot be ensured and glucose goals are not as tight, postprandial dosing would still be appropriate.