Effect of long-term dietary protein intake on glucose metabolism in humans

Abstract

For different reasons interest in dietary protein intake has recently increased in diabetes research. Manipulation of protein ingestion has been used to slow down diabetic nephropathy [1]. Furthermore, epidemiological studies indicate that the quantity and quality of protein ingestion affects the expression of Type I (insulin-dependent) diabetes mellitus [2,3]. We have previously shown that a high protein diet accelerates the progression of the autoimmune loss of endogeneous insulin secretion in patients with Type I diabetes [4,5]. In general, high protein ingestion could be more detrimental in clinical situations with impaired glucose tolerance than is recognized; there is evidence that high protein intake promotes diabetes. Therefore, more knowledge is needed to decide in what way high dietary protein intake changes glucose metabolism in humans.The protein supplied by a meal is a major stimulator of insulin secretion [6]. Dietary protein potential- Diabetologia (2000) Results. Glucose-stimulated insulin secretion was increased in the high protein group (516 45 pmol/l vs 305 32, p = 0.012) due to reduced glucose threshold of the endocrine beta cells (4.2 0.5 mmol/l vs 4.9 0.3, p = 0.031). Endogeneous glucose output was increased by 12 % (p = 0.009) at 40 pmol/l plasma insulin in the high protein group, but not at higher insulin concentration whereas overall glucose disposal was reduced. Fasting plasma glucagon was 34 % increased in the high protein group (p = 0.038). Fractional gluconeogenesis was increased by 40 % in subjects receiving a high protein diet as determined by both methods. Conclusion/interpretation. High protein diet is accompanied by increased stimulation of glucagon and insulin within the endocrine pancreas, high glycogen turnover and stimulation of gluconeogenesis. [Diabetologia (2000

Effects of lupin-enriched foods on body composition and cardiovascular disease risk factors: a 12-month randomized controlled weight loss trial

“…Acutely, dietary protein enhances insulin secretion, 43,44 leading to increased glucose disposal. Although data from epidemiological studies indicate that this may not result in improved insulin sensitivity, 45,46 positive effects of higher protein intakes have been observed in some intervention studies. 21,47,48 The lack of effect on glucose concentrations in the current study may be because of population selection.…”

Transcriptional co-factors and hepatic energy metabolism

“…At the same time, by interfering with pyruvate dehydrogenase activity, acetyl-CoA inhibits glucose utilization, further promoting hepatic insulin resistance [32]. Gluconeogenesis is further stimulated by increased levels of amino acids, thereby exacerbating diabetic hyperglycemia [33][34][35][36]. In response to insulin, diacylglyerol (DAG) levels in the cell rise, leading to the activation of protein kinase C (PKC) which phosphorylates glycogen synthase resulting in its inactivity [37].…”

Signal Transducer and Activator of Transcription 3 (STAT3) Mediates Amino Acid Inhibition of Insulin Signaling through Serine 727 Phosphorylation

“…Nutrient overload in affluent societies has been associated with increased occurrence of metabolic syndrome (1,2). High protein diets are associated with altered glucose metabolism and increased occurrence of type II diabetes (3,4). Elevated plasma concentrations of amino acids have long been found in obesity and insulin-resistant states (5)(6)(7)(8).…”

“…The signal transducer and activator of transcription (STAT) 3 proteins are activated by a wide range of cytokines and growth factors. STAT3, activated by the IL-6 family of cytokines among others, is phosphorylated on two key residues, Tyr 705 and Ser 727 .…”