Page 11 - Read Online

Page 6 of 13 Fearon et al. Metab Target Organ Damage 2022;2:13 https://dx.doi.org/10.20517/mtod.2022.12

groups
Significant correlation between M and weight for
both groups
T2DM: Type 2 diabetes mellitus; BMI: body mass index; VLED: very-low-energy diet; bg: blood glucose.

Very-low-energy diet
A very-low-energy diet (VLED) can improve glycaemic control and has been utilised as an isolated intervention or as a preoperative bridging intervention
before elective surgery. A number of randomised trials have demonstrated the efficacy of a medically supervised VLED with up to 60% remission of T2DM
after 12 months and 30% after 24 months. Younger people with a shorter duration of T2DM are most likely to achieve remission, and the improvement in
glycaemic control seems to happen very soon after the commencement of the VLED, indicating that the initial improvement is weight loss independent.
[21]
Weight loss maintenance does not directly correlate with remission of T2DM, indicating a non-linear relationship .
A recent sub-analysis of the multicentre Almased Concept Against Overweight and Obesity and Related Health Risk (ACOORH) trial showed that longer-
term insulin reduction correlated with weight reduction, and people with obesity who undertook a phased 24 weeks high glycaemic, low-energy diet involving
three meals per day reduced their insulin levels significantly more than those who received nutritional advice and monitoring only . The profound impact of
[22]
calorie restriction was further demonstrated by Pournaras et al. They randomised people with T2DM undergoing Roux-en-Y gastric bypass (RYGB) to either
an 800 calorie/day preoperative diet or no preoperative diet (ND). After two weeks, the VLED group had significantly improved whole-body insulin sensitivity.
Two weeks post RYGB, both groups showed similar improvements in whole-body insulin sensitivity. However, the VLED group did not demonstrate much
[23]
further improvement than what had been achieved after the VLED .

A VLED can be used as a preoperative ‘liver shrink’ diet to enable liver retraction and safer exposure for upper gastrointestinal surgery. Colles et al. used serial
imaging to demonstrate a significant reduction in liver volume (LV), visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) at weeks 2, 4, 8 and
12 while a VLED was followed. The overall relative reduction in LV, VAT and SAT was 18.7%, 16.9% and 17.7%, respectively. This correlated with a significant
decrease in fasting insulin, HbA1c and cholesterol. After two weeks, 80% of the reduction in LV occurred. The VLED was composed of shakes which
amounted to 456-680 kcal/day. People who were due to undergo laparoscopic adjustable gastric band surgery were enrolled . A systematic review from 2016
[24]
included 15 studies that looked at VLED before surgery (> 80% bariatric surgery) and included people with and without T2DM. There was high variation in
the included studies. Still, an overall high compliance rate was tolerated. A 5%-10% total weight loss and > 10% reduction in LV were shown, reflecting an
overall improvement in metabolic status, including improved insulin resistance and blood glucose levels. The impact on perioperative hyperglycaemia was not
measured/reported . The complex interaction between NAFLD and DM is highlighted by the frequent coexistence of the two diseases. The prevalence of
[25]
NAFLD is doubled in those with T2DM, and they also have a much higher incidence of complications such as cirrhosis and the development of hepatocellular
carcinoma. Stefan and Cusi outline three mechanisms for developing NAFLD, including a strong genetic component whereby specific genetic variants are
associated with both severe and complicated forms of NAFLD and DM and dyslipidaemia. A second mechanism is increased hepatic de-novo lipogenesis,