The global pandemic of type 2 diabetes (T2D) has increased noticeably over the last few dedicates with an estimated 463 million people affected globally since the 2019, which is projected to increased to 700 million by the year 20451. Notably, T2D is a multifactorial disease that is characterised by insulin resistance and impaired insulin secretion, which can lead to severe complications such as microvascular, macrovascular, diabetic nephropathy and retinopathy. Recent public health data has highlighted the importance of prevention, namely through lifestyle factors such as adopting a healthy diet early on. Flavonoids, which are plant-derived phytochemicals has recently gained significant attention since small scale studies has shown an inverse correlation between flavanol intake and incidence of diabetes. Therefore, this literature aims to explain the relationship behind flavonoid intake and lower risk of T2D.
Diabetes mellitus (DM) is a global pandemic that affects 1 in 10 individuals aged 20-79 years and ranked among the leading causes of premature mortality. Interestingly, the global incidence and prevalence of diabetes has risen exponentially and is projected to reach around 700 million by 20451. DM is a metabolic disease, involving inappropriately elevated glucose levels and categories as two major subtypes, the type 1 (T1D) and T2D. diabetes. Patients with defective insulin secretion are considered to have T1D, and they typically present in their childhood or as adolescents. Contrarily, T2D affects middle-aged and older adults who have prolonged hyperglycaemia due to poor lifestyle and dietary choices2. T2D accounts for more than 90% of all type of DM, globally and is characterised by insulin resistance and insufficiency3. DM is also a major cause of morbidity and mortality in Hong Kong, in addition to being the 11th most common cause of deaths locally4. Even though T2D has traditionally be associated with middle and late adulthood, there has been an increasing number of cases reported in children, adolescents, and young adults over the last few years, driven by obesity and poor diet, raising a serious public health concern3.
One of the reason behind this concern stems from the fact that early-onset of T2D is associated with a more severe disease phenotype, characterised by faster decline in beta-cells (β-cells) of pancreas, leading to necessitation of insulin therapy much earlier, alongside with an increased lifetime risk of developing unfavourable long-term outcomes3. More worryingly, early-onset of T2D is associated with an estimated median 7 years of life lost in those with a diagnosis between the age of 21 and 40 years compared to those without diabetes5. The seriousness of early-onset of T2D was reported in an epidemiologic study by Misra et al., (2022) who reported seeing a substantial number of individuals under the age of 40 with early-onset of T2D from most deprived areas of England. Furthermore, most of these individuals were less to attain the guideline recommended levels of glycated haemoglobin (HbA1c) due to inadequate care5. The local diabetic landscape is not significantly better since many insulin dependent diabetics under the age of 40 in Hong Kong are only provided continuous glucose monitoring (CGM) devices for a limited period of time, unlike other nations such as the United Kingdom where personal CGM is provided to all T1D and some T2D patients who are insulin dependent, according to a report by the Chinese University of Hong Kong (CUHK). Furthermore, the high cost of CGM ($1,000-$3,000+ Hong Kong Dollars [HKD] per month) is also one of the limiting factors in diabetic management, particularly for underprivileged socioeconomic groups6.
A median 7 years of life lost in those with early-onset T2D...
The primary goal in the management of diabetes is to achieve as near normal regulation of blood glucose as possible. Thus, both the type and total amount of carbohydrates (CHO) consumed influences the glycaemia7. Various clinical studies have demonstrated the potential of natural flavonoids in managing diabetes8. In addition, regular cocoa consumption (up to 100 g of chocolate or 54g of cocoa) has shown to improve blood pressure (BP), insulin sensitivity, and lipid levels in patients with T2D. These findings were explored in a double-blinded randomised, placebo-controlled trial by Dicks et al., (2018) which included 42 hypertensive patients with T2D (stable pharmacological treatment, with good adjustment for glucose metabolism, lipids, and BP). Patients were randomised to capsules with 2.5 g/day of a flavanol-rich cocoa or cocoa-free capsules for 12 weeks. Participants were expected to maintain diet, lifestyle and medications. The results showed that cocoa treatment did not affect BP, nor glucose metabolism (glucose, HbA1c, insulin, Homeostatic Model Assessment for Insulin Resistance [HOMA-IR]) and lipids (triglycerides, total cholesterol, low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C]). Body weight, fat mass and nutrient supply remained unchanged when compared to placebo. Therefore, the study found no correlation between cocoa intake and improvement in cardiometabolic parameters9.
Contarily, a systematic review and meta-analysis by Chen et al., (2022) indicated that cocoa products confers a positive effect of LDL-C, triglyceride, blood glucose, and C-reactive protein (CRP) in long-term. Furthermore, it also indicated that there are beneficial effects of cocoa products intake on cardiometabolic biomarkers for T2D, especially on blood glucose, lipid metabolism (LDL-C and triglycerides) and inflammation (CRP)10. These findings were further supported by a more recent study performed by Lin et al., (2024) that explored the relationship between different types of chocolate (dark, and milk chocolates), as well as total chocolate consumption with risk of T2D development. Remarkably, 18,862 individuals with incidental T2D were identified during the 829,175-person year of follow-up. After adjusting the personal, lifestyle, and dietary risk factors, participants consuming ≥ 5 servings/ week of any chocolate showed a 10% (95% confidence interval [CI] 2% to 17%; P trend=0.07) lower rate of developing T2D compared with those who never or rarely consumed chocolate. Interestingly, participants who consumed ≥5 servings/week of dark chocolate showed a staggering 21% (5% to 34%; P trend=0.006) lower risk of developing T2D; however, no such reduction was found in participants who consume milk chocolate. These demonstrated that dark chocolate consumption correlated to a lower risk of T2D, whereas milk chocolate consumption correlated to weight gain only1. Nonetheless, these findings are still preliminary and more long-term trials are necessary to confirm the relationship between dark chocolate consumption and T2D. However, individuals are strongly recommended to maintain a healthy lifestyle that consists of a balance diet, and exercise. In conclusion, T2D prevention remains a public health concerns and healthcare providers should take an active role in prevention of T2D by promoting a healthier life choices for their patients.
Dark chocolate consumption may correlate to a lower risk of developing T2D, however, it is equally important to maintain a healthy lifestyle...
Figure 1: Multivariable adjusted, pooled, dose-response associations between chocolate intake and risk of type 2 diabetes in NHS, NHSII, and HPFS1. NHS=Nurses’ Health Study; NHSII=Nurses’ Health Study II; HPFS=Health Professionals Follow-up Study; MET-h=metabolic equivalent tasks per hour
References
1. Liu B, et al. BMJ 2024; 387: e078386. 2. Sapra A, StatPearls Publishing LLC.; 2024. 3. Strati M, et al. Endocrine 2024; 85(3): 965-78. 4. Protection CfH. Diabetes Mellitus. 2024. https://www.chp.gov.hk/en/healthtopics/content/25/59.html (accessed 13/12/2024 2024). 5. Misra S, et al. Diabet Med 2023; 40(1): e14940. 6. Faculty of Medicine TCUoHK. New initiative launched to support and empower young people with diabetes. 2023. https://med.cuhk.edu.hk/press-releases/new-initiative-launched-to-support-and-empower-young-people-with-diabetes (accessed 13/12/2024. 7. Reynolds A, et al., eds. Endotext. South Dartmouth (MA): MDText.com, Inc. 2000. 8. Bouyahya A, et al. Heliyon 2024; 10(9): e29718. 9. Dicks L, et al. Nutrients 2018; 10(10). 10. Chen X, et al. Int J Food Sci Nutr 2022; 73(5): 571-87.
