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.

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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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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