Fasting plasma peptide-YY concentrations are elevated but do not rise postprandially in type 2 diabetes

To the Editor: Weight loss appears to be particularly difficult to achieve in patients with type 2 diabetes compared to their non-diabetic counterparts [1]. The hormones peptide YY3–36 (PYY) and ghrelin are implicated in the regulation of appetite, energy balance and the pathophysiology of obesity. PYY is released from L-cells in the gut in response to food [2]. Fasting concentrations are lower and postprandial responses attenuated in obese subjects [3], and infusions of PYY to mimic the postprandial concentrations found in lean subjects reduce appetite and food intake in obese subjects [3, 4], suggesting a potential role in the pathogenesis of obesity. Peripheral administration of ghrelin increases food ingestion [5, 6], and prolonged administration leads to obesity [5, 7]. Circulating ghrelin shows preprandial peaks and postprandial troughs suggesting a role in meal initiation. Against this background, we sought to determine whether type 2 diabetes, independent of obesity status, affected the prandial regulation of PYY and ghrelin in a manner that would explain both the predisposition to increased energy intake and weight gain, and the difficulties in achieving weight loss seen in type 2 diabetes. The study was approved by the local ethics committee and subjects, who were volunteers, gave written informed consent. We studied 11 subjects with diet-controlled type 2 diabetes and 16 control subjects of similar age, sex and BMI. All subjects with diabetes were free from complications and had an HbA1c