University of Virginia Health System
Nutrition Support E-Journal Club
Vanschoonbeek K, Lansink M, van Laere KM, Senden et al. Slowly digestible carbohydrate sources can be used to attenuate the postprandial glycemic response to the ingestion of diabetes-specific enteral formulas. Diabetes Educ. 2009 Jul-Aug;35(4):631-40.
A randomized double-blind crossover study that compared the glucose, insulin and triglyceride response to a single 200mL "bolus" of 4 different enteral feeding formulas in 15 patients with type 2 diabetes mellitus after an overnight fast. The formulas tested were 2 new "glucose control" formulas, a high fat "glucose control" formula and 1 standard enteral formula. The new glucose control formulas provided slowly digested carbohydrates (Isomaltulose formula 1 and Sucromalt for formula 2) as 47% of the calories. Subjects visited the lab 4 times (4-10 days between visits) and consumed the formula from nontransparent drinking bottles over 5 minutes to approximate a bolus tube feeding. Blood samples were obtained at baseline and every 15 minutes up to 90 minutes, and then every 30 minutes up to 4 hours.
Variables monitored: peak postprandial plasma glucose, plasma insulin response, postprandial triglyceride response, lipid profile, plasma glucagon.
Inclusion and Exclusion Criteria were:
Inclusion criteria: Outpatients with type 2 DM controlled with only oral hypoglycemic agents that had not been modified in the past 2 mos.
Exclusion criteria: Patients with Type I DM, acute GI disease within 2 weeks prior to study, impaired liver or renal function, cardiovascular disease, or any patients using insulin.
Major Results reported by authors:
The investigators reported that the peak plasma glucose concentration was not significantly different between the 3 "diabetes" formulas, but the peak plasma glucose was significantly greater after ingestion of the standard formula (p<0.05).
Plasma glucose response over 4 hour period after ingestion of the formula was greater for the standard formula than for the other 3 formulas. (p<0.05)
The insulin response as an incremental area under the curve (iAUC) was higher for the standard formula than for the other 3 formulas.
Triglyceride response as iAUC was significantly (p<0.05) greater after ingestion of the hi-fat formula than for the other 3 formulas.
There was no significant time x treatment differences detected in plasma lipid profile or for glucagon concentrations.
"The authors concluded that diabetes-specific enteral formulas rich in slowly digestible carbohydrate sources can be equally effective in attenuating the postprandial blood glucose response as low-carbohydrate, high-fat enteral formulas without elevating the plasma triglyceride response."
This was a well planned and controlled study with randomized, double-blind, crossover design. The number of subjects was relatively small (15), but appeared adequate for the purpose of comparing glucose and insulin response considering the crossover design, with each person essentially serving as their own control.
The peak plasma glucose was not only statistically different between the formulas, but also appeared to be a clinically relevant difference. The peak-plasma glucose after the "diabetes-specific" formulas ranged from 187-196mg/dl, while after a bolus of standard formula peak-plasma glucose was approx. 237mg/dl.
The results appropriately report plasma glucose over a 4 hour period, from the graphs we noted that the primary difference in plasma glucose after the standard formula occurred between 30 and 90 minutes after consumption, and that after 120 minutes there was no significant difference in plasma glucose or insulin between any of the formulas. Although plasma triglyceride concentration was reported as significantly higher after the high-fat glucose-specific formula, we noted that all of the triglyceride values were well within the normal range, therefore it is unclear that there is any clinical significance regarding the triglyceride values.
Our group discussed that while this study accomplished it's goal of comparing formulas with slowly digested carbohydrate sources to high-fat diabetes specific formulas, the clinical implications of this study are less clear. There are no studies of glucose-specific enteral feeding products that demonstrate an improvement in any patient outcome that matters. Considering that diabetes-specific products cost more per calorie than standard formulas, this is an important consideration. Conceivably, there may be a clinical niche for diabetes-specific products in some patients with type 2 diabetes receiving bolus feedings - especially those with marginal glucose control with standard products while on appropriate medications.
However, the results of this study may have no bearing on patients that receive cyclic or continuous feedings where the slow infusion rate essentially reproduces a slowly digested carbohydrate. Our standard 1 calorie per mL formula at 75mL/ hour delivers 10 grams of carbohydrate distributed over an entire hour -- now THAT is slow release carbohydrate. Likewise, a patient that receives insulin with bolus feedings should have no problem simply matching insulin dose with grams of carbohydrate. Standard enteral formulas can be considered the ideal "diabetic diet" for insulin-dependent diabetics considering that you get the exact same grams and calories each feeding.
Our Take Home message:
This study demonstrates that a bolus feedings with diabetes-specific enteral formulas with slowly digested carbohydrates provides similar glucose and insulin response, with lower postprandial triglyceride concentrations than high-fat diabetes-specific feedings.
Further studies will be required to determine if use of diabetes-specific enteral formulas result in clinically important outcomes for patients or whether they are cost effective.
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Joe Krenitsky MS, RD
Carol Rees Parrish MS, RD
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