Spontaneous postprandial hypoglycemia (PPHG) may occur after Roux-en-Y gastric bypass (RYGB) in morbidly obese patients with type 2 diabetes, according to study results published in Diabetologia.

RYGB ameliorates glucose metabolism in patients with type 2 diabetes, but it remained unclear prior to this study whether there is a relationship between this amelioration and the later development of PPHG.

To further investigate the relationship between RYGB and PPHG in patients with type 2 diabetes, investigators followed 35 obese individuals with type 2 diabetes through RYGB. Participants underwent an oral glucose tolerance test before and 24 months after surgery. Individuals were diagnosed with PPHG when they had a plasma glucose level of ≤3.3 mmol/L without taking glucose-lowering agents. Investigators also measured insulin sensitivity by the oral glucose insulin sensitivity index and beta-cell function was estimated with mathematical modeling of plasma glucose, insulin, and C-peptide concentrations.

Overall, 11 of the 35 participants developed PPHG. The PPHG group exhibited lower body mass index, poorer glycemic control, and an earlier glucose peak before surgery compared with the non-PPHG group (all ≤.05). In addition, the duration of diabetes was shorter in the group with PPHG and insulin sensitivity was elevated in PPHG (=.03).

Fasting glucose and insulin levels declined similarly in the PPHG and non-PPHG groups after surgery. Insulin secretion was elevated in the first hour of the oral glucose tolerance test in the PPHG group compared with the non-PPHG group (=.04). The PPHG group also exhibited a greater increase in beta-cell glucose sensitivity (=.002).

The glucagon-like peptide 1 (GLP-1) response was lower in the PPHG group than in the non-PPHG group before surgery (=.05) and increased by a larger amount after surgery. Plasma glucagon levels were lower in the PPHG group than the non-PPHG group 2 hours after glucose ingestion in the postsurgery oral glucose tolerance test.

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The results of this study indicate clinicians should be aware that PPHG may occur after RYGB in patients with type 2 diabetes, independent from diabetes remission. The researchers also determined a likely sequence of pathogenesis based on their results: early gastric emptying, expected beta-cell secretory response with GLP-1 release, and late hypoglycemia with inadequate glucagon counterregulation. Additional research is needed to determine effects that may impact pathogenesis.

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Reference

Guarino D, Moriconi D, Mari A, et al. Postprandial hypoglycaemia after Roux-en-Y gastric bypass in individuals with type 2 diabetes [published online October 12, 2018]. Diabetologia. doi:10.1007/s00125-018-4737-5