Week 8: Lecture 39: Diet and Type 2 Diabetes: Epidemiological Evidence and Prevention Strategies

Hello and welcome dear learners to the NPL course on nutritional epidemology a way towards a healthy life for the module 4 diet nutrients dietary patterns and disease epidemology for the chapter 39 we'll be taking about diet and type 2 diabetes, epidemological evidence and prevention strategies. So the burden of type 2 diabetes along with dietary determinance of diabetes risk, glycemic index and glycemic load, the role of whole grains, fiber and dietary patterns, evidence from prospective cohort studies, preventive strategies and policy implications will be taken for discussion. Now let me talk about the global burden of type 2 diabetes. The relationship between obesity and type 2 diabetes malitis is also epidemologically intervened that the term diabetes is widely unutilized to reflect their shared driving mechanisms. The macro epidemology for international diabetes federation IDF where diabetes at last provides a stark insights into assillating crisis. While global data sets capture the overall trajectory localized data highlights severe regional vulnerability and particularly across South Asia. Here you can see that the total diabetes prevalence is like 540 million adults and projected to reach as 783 millions by 2045. India particularly if you have to talk the national reality is like we have 101 million adults which are clinical diabetic 136 million adults are pre-diabetic and the prevalence hits about 11.4 four nationally. So what are the public health uh significance and you can talk that over 90% of cases are type two. India has surpassed the historical estimates becoming the global epicenter of metabolic speed up. What is the undiagnosed fraction now? that the undiagnosed fraction in global scenario we can say that 240 million adults one in two cases globally are unaware and over 50% of adult diabetic cases in India remain completely undiagnosed so here you can understand the iceberg phenomena where the high screening barriers mean metabolic damage ne nephropathy neuropathy Obesity is often locked in a clinical diagnosis. Adult overweight and obesity baseline 2.5 billion adults where the BMI is lower than 25 kg per meter squared where 30.7% of women and 27.3% of men age between 15 to 49 are overweight and obese. The NFHS 6 version marked a sharp increase from NFHS 5 showing a rapid metabolic shift across both rural and urban population. The Asian Indian phenotype that the Y paradox the thin fat India enigma genetically characterized by a lower generalized BMI but an exceptionally high percentage of body fat and visceral adiposity. The Y paradox explained name after researchers Yagnik and Din. The classical study compared a native Indian researcher to a British researcher with the same low healthy BMI of 22.3. The findings indicated that the Indian researcher possessed a catastrophic 21.2% of body fat compared to a British researcher highly fit with 9.1. The metabolic disparity stating that any given body weight or BMI with a South Asian individual display a profound abdominal adiposity that is called as central obesity. The deep visceral fat packing around a core metabolic organs that is liver, pancreas and heart. Significantly higher baseline insulin resistance and circulating triglycerides. When understanding the epidemology of diabetes in South Asia, we have to throw out traditional western assumption. The YI paradox proves that a normal or a lean looking body weight can hide advanced metabolic disease. This thin fat phenotype means our population are structurally prone to accumulating visceral fat rather than safe subcutaneous fat. As a result, metabolic tissues are exposed to lipotoxicity at weights than western clinic would consider entirely safe. So moving beyond BMI, the waist to height ratio. The failure of BMI screening traditionally body mask index completely misses the ectopic and visceral fat distribution. The new diagnostic standard that the public health epidemology is shifting towards is waist to height ratio as a superior screening matrix. The mathematical indicator of weight to height ratio that is waist circumference in centm divided by height in cm. The clinical cutff of weight to height ratio is lesser than.5. So the greater ratio than 0.5 indicates elevated cardiovascular and type 2 diabetic risk. The simple public health message is like keep your waist circumference to less than your half your height. The example is if your height is 184 cm your maximum healthy waist circumference is exactly half of that that is 184 cm divided by 2 that is 92 cm. [snorts] So to meet this guideline your waist circumference should be less than 92 cm approximately that is 36 in. So, how to measure it accurately? To get a true reading that matches the clinical guidelines, the right spot, what is the right spot? Find the midpoint between the bottom of your ribs and the top of your hip. So, usually across your belly button. So the technique is like breathe out normally before measuring and ensure the tape measure in a snug against your skin. So put not squeezing or building tightly. So the multicentric studies across India confirmed that weight to height is significantly stronger predictor of type 2 diabetes malitis, hypertension and metabolic syndrome than the standard BMI or waist circumference alone. Why does BMI fail our population? The reason is it is simple because of total weight and not fat distribution. A heavily muscled individual can have a high BMI and completely healthy while an Indian adult can have a normal BMI but severe visceral fat accumulation around the liver. International and national guidelines now recommend using weight to height ratio. It scales perfectly across height and ages and the score of or.5 tells a clinician immediately that ectopic fat is driving an active metabolic risk and long before the BMI flags it up. The national burden that ICMR and Indilab and NFHS 6 data which is shifting that the epicentric shift that India has officially passed historical projection transition from the region to a potential risk actually to the absolute global epicenter of metabolic speed up. The core numbers is like 101 million Indian adults currently live with clinical diabetes and 136 million Indian adults are currently in the state stage of pre-diabetic. The national diabetes prevalence has reached on unprecedented that is 11.4%. The NFHS6 obesity surge the overweight and obesity rates have completely inverted across soio economic classes. 30.7 of women and 27.3% of men age 15 to 49 are now clinically overweight or obese. The rural explosion. The surge is no longer just an urban. The hyperprocessed food have deeply penetrated the rural ecosystem driving a dual countrywide crisis. The latest national data from the ICMR INDB study and the national family survey NFHS6 outline a public health emergency. We are looking at over 230 million individuals who are either diabetic or pre-diabetic. And furthermore, we can see that we look at NFHS 6 obesity surge nearly a third of the reproductive age female population is now overweight or obese. So this is a massive shift from previous survey rounds showing that cheap ultrarocessed food have saturated rural market removing any historic insulation these communities had from the diabetics and metabolic diseases. What are the dietary determinants of diabetic risk? The modern view of dietary impact on type 2 diabetes beyond the total carbohydrates where you can see the traditional view and now you can see the nutritional epidemological shift where you have the ultrarocessed food with lined up and the critical dietary risk that we can see it over here where the sugar sweet beverages industrial trans fats and high saturated fats and advanced glycated end products which are putting the risk and making more that your calorie intakes are high and your baseline of the BMI. The glycemic index GI and the glycemic load. To accurately quantify how carbohydrates impact blood glucose level, public health nutrition relies on two specific metrics rather than simple carbohydrate counting. The first is glycemic index. Your glycemic index ranks carbohydrates on a scale from 0 to 100 based on how quickly and significantly they raise the blood glucose level compared to a pure glucose reference control. High GI foods which are greater than 70 rapidly digested and absorbed. They trigger the steep glucose spikes followed by compensatory insulin surges which cause a rapid drop in blood sugar that stimulates hunger. The lower GI food lesser than 55 digested slowly providing a gradual sustained release of glucose instead into the bloodstream. Now we'll understand the glycemic load. While the GI measures carbohydrated quality, glycemic load accounts for both quality and quantity within a standard real world serving size. It is calculated using the formula that is GL glycemic load is equal to GI the net carbided serving in grams divided by 100. The fourth metabolic combination, the interaction between carbohydrate quality and portion quantity determines the actual post praial that is postmeal blood glucose curve. The high GI plus high GL that is the pancreatic shock. The food which gives is like instant white rice, cornflakes, sport drinks and refined for floor baked goods. The curve is like a sharp immediate spike in the blood glucose triggering a massive insulin surge. This cause you rapid insulin driven clearance from the blood resulting into a sudden drop in blood sugar reactive hypoglycemia that stimulates you instant hunger. A high GI plus low GL that is a portion buffer where the food that is watermelon, pumpkin and boiled carrots. What is the curve given? The sugar presents absorbs rapidly into the bloodstream that is a high GI. But because a standard serving contains a very few net carbohydrate being mostly water and fiber, the total absolute rise in blood glucose is minimal and easily managed by normal pancreatic function. Now low GI plus high GL that is a delayed run. So you can see the food are large proportion of whole wheat pasta, large commercial bowls of brown rice and a high fructose sweetened desserts. The curve is that the food breaks down slowly at first avoiding an immediate drastic spike. However, because the total volume of carbohydrate consumed is massive, it releases a steady high volume of glucose over several hours. So this causes long periods of high blood sugar. Then strain pancreatic beta cell over time. Then is low GI plus low GL that is a metabolic gold standard. The fluid are lentils, chickpeas, non-starchy vegetables and quina. The curve is a gentle low amplitude wave that supplies a stable steady stream of energy without overstimulating insulin pathways. This is the GI oblique GL matrix serving the size matrix where you can see the high GI and low GL. high GI and high GL in where it is showing for the rice part where the low GI and low GL is balanced to show in the chickpeas where versus the low GI obl strain to be shown for an over serving of the strain that is being shown into the serving of rice. Now the gluccoinetic lesson. The high glycemic index does not equal atom at auto atomatic metabolic damage. The portion size dictates the absolute glycemic burden. The high GI versus low GL exception watermelon. Safe is the moderate portions for individuals with type 2 diabetes malitis because it contains minimal net carbonate per serving. The low GI per high GL hazard large portions of unrefined starches while marketed as healthy due to low GI overserving unrefined starches delivers as excessive carbohydrate. So this leaves blood glucose elevated for hours and compounding insulin resistance. What is the public health application? Nutrition guidelines must emphasize both carbohydrate selection and a portion management to successfully prevent a metabolic syndrome. This matrix is where many clinical nutrition plan succeeds or fail. If you look at the top left corner, high GI but low GL, this explains why we don't need to ban fruits like watermelon or a pumpkin from a diabetic patient's plate. Yes, there sugar absorb fast but there simply isn't enough that the total sugar is in standard slides to stress the pancreas. Conversely, look at the bottom right where you can see the lower GI but high GL. So this is a classical trap for an health conscious people. They eat massive bowls of brown rice or whole grain pasta thinking it's safe because it is a low GI but because the total volume of carbide is so high it creates a delayed balcony. So glucose leaks into the blood for hours on end and keeping insulin level high and exhausting the pancreas just as badly as refined junk food. Now the whole grains fiber and dietary patterns. We'll try to understand a role where the protective dietary components act as a structural physical barrier that temper the body's metabolic response to food. Where you can understand whole grains versus refined grains. Whole grain preserves all three of its original anatomical component that is germ, endosperm and bran. The refined grain strip away the bran and germ turning the food into a rapidly accessible starch bomb. Epidemological data shows that replacing refined grains with three uh daily servings of authentic whole grain reduces the type 2 diabetes malitis risk by 20 to 30%. The protective mechanism of dietary fiber. So dietary fiber particularly viscous soluble fiber such as oats, legumes and barley which reduces the diabetic risk through three clear biological pathways. You can see it over here that is that intestinal viscosity, steady signaling and microbone fermentation. Then this is high impact dietary patterns. The Mediterranean diet. Meditine diet is characterized by high intakes of extra virgin olive oil, nuts, legumes, unrefined grains, fruits and vegetables. It is consistently associated with significantly lower baseline of HBA1C levels and reduce risk of progressing from pre-diabetic to clinical type 2 diabetes. The dietary approaches to stop hypertension that is a DASH diet. So high in low-fat uh dairy, whole grains and lean proteins while minimizing sodium and red meat. DASH improves insulin sensitivity by providing rich amounts of magnesium potassium which acts as essential co-actor in intracellular insulin signaling. What is the evidence from the prospective cohort studies? As randomized control trials cannot easily force human cohort to follow strict diet for decades, public health relies heavily on massive multi-deade prospective cohort studies. The global evidence, the most robust evidence defining the relationship between diet and diabetes comes from the three iconic epidemological cohorts. The nurses health studies that is NHS1 and NHS2. the health professional follow-up studies that is HPFC and the European investigation into cancer and nutrition that is EPIC study the key prospective cohort reveals the diabetic risk which is being given by NHS and you can see the more than two lakhs participants followed for 30 plus years have confirmed that 33% lower risk of type 2 diab diabetes compared to the lowest quentile. The epic interact that 12,000 incidents of type 2 diabetes cases across Europe which has proved that the high consumption of sugar sweetened beverages elevates the diabetic risk and entirely independent of the total body adiposity or baseline body fat. What are the prevention strategies and policy implication? The classical diabetes prevention program DPP trial proved that intensive lifestyle interventions focusing on 7% weight loss and 150 minutes of weekly moderate exercise reduced the progression from pre-diabetic to type 2 diabetes by 58%. Outperforming the standard clinical drug metapformine which reduced the progression by only 31%. However, translating the individual clinical success into broad public health outcome requires shift from individual advice to structural environmental policy. When moving from the clinical trials like DPP to population level policy, public health intervention must adapt to a country's economic development stage. A single policy can yield vastly different outcomes depending on the infrastructure of the local market. the policy implementation divide where you can see on the either side the highinccome countries which are more with structured retail markets and clear nutrition literacy and focus on reducing excess energy. This is the triple action of fiber. And now you can see the low and middle inome countries where there is a massive informal food sectors which are diverse which are underregulated vendors challenge for standard labeling and enforcement. Also high baseline under nutrition which is coming with nutrient leap gaps which is like widespread malnutrition existing need for nutrient-rich food access. Also focusing on managing the double burden which is coming with under nutrition and a double burden of obesity and over nutrition where the policy must address both under nutrition as well as the rising obesity simultaneously which is an integrated health policy which will give an answer for this. Now crosscountry comparison of food policies and why we need to do this the highincome countries where you can say like UK and Europe the strategies are tiered with manufacturers liies and you may see that UK soft drink industry outcome the high effective it uses market pressure to force food companies to reformulate recipes below lower sugar thresholds removing thousands hundreds of tons of sugar without raising prices for the consumers and emerging developing economies like India and Brazil the mandatory front of pack labeling FO and marketing the bands I'm not saying what it is wrong or what it is right over here but LMIC challenge that taxing packaged goods can backfire by pushing low income consumers towards a cheap untaxed and unregulated informal street foods which are often high in trans fats and sodium. The lowincome underdeveloped regions like subsahar and Africa where the strategy is doubled duty actions. What they do they track the standard western anti-obesity campaign that simply strict calories can accidentally worsen the undernutrition and wasting in vulnerable populations. We cannot copy paste public health policies from wealthy nations into developing ones. In the UK, a triggered sugar tax works beautifully because almost everyone buys their food from structured supermarket. But in India or Kenya, if we place a high tax on a packed food product, a low income worker may simply switch to an unregulated local street vendor. This vendor's food isn't taxed but it might contain even higher level of industrial trans fats. In developing nations, our policies must focus on front of pack warning levels and protecting school environments rather than relying slowly on flat price taxes. What is the global syndomic framework? The Lancet Commission global syndemic report changes how we look at prevention about obesity, undernutrition and climate change are not separate problem. They reflect a paradigm shift. Look at the agriculture subsidies government spends billions keeping on corn, soya and palm oil incredibly cheap. This makes ultrarocessed food the most affordable option globally and which is driving towards obesity in the west. and a double burden of malnutrition in countries like India with industrial cattle farming destroying our environment. True prevention requires a triple duty action like reforming the food system to make healthy sustainably growing whole foods and the most affordable option on the market. Here you can see a comprehensive global policy matrix which you should try to highlight towards understanding the highincome countries versus developing countries and the least developed countries how they are putting the primarily nutrition crisis and the high impact policy tools at that action and a very key structural barriers which they should try to overcome which they make it into their strategy plan. What is the systemic policy initiatives? We should be triggered to see that the tiered sugar taxes rather than simple flat tax. Countries like UK implemented tiered libby structures that tax manufacturer based on the specific concentration of the sugar per 100 ml. This policy is very successful and you can say it is even helping the consumers also. Staple food biofortification and whole grain subsidies which are shifting agriculture subsidies away from the corn syrup production towards supporting the cultivation and processing the whole gay grain and legumes making healthy dietary staples the most affordable option. structural school and workplace food procurement laws which is not banning but legally banning the ultra processed tanks and high GI foods from public institutions, hospitals, school, cafeterias and replacing with a whole food alternative to protect the metabolic health at scale. What is the key takeaway from this chapter is that the visceral crisis type 2 diabetes is primarily driven by ectopic fat deposition in visceral organs. This causes an advanced insulin resistance and eventually it is creating a pancreatic beta cell failure. The quality outweigh quantity. Managing diabetes risk requires looking past simple carbohydrate counts. Public health strategies must prioritize carbohydrate quality by choosing low glycemic load foods and intact whole grains over refined starches. There is also an epidemological certaintity that we should look that is decades of the prospective data from the cohorts like NHS uh NHS and EPIC studies provide that diet which are high in ultrarocessed food and sugar drinks directly drive insulin resistance and independence of the genetics. So we should more focus on environment shape prevention. And what are those? Where we understand that the intentional lifestyle changes can prevent over half of the type 2 diabetic cases where sustainable population level production requires more structural policies which are tiered with sugar taxes and whole grain subsidies. So with this we come an end to this chapter where you can use this references to understand more in detail with the thorough implementation on understanding each of the case studies which are more pointing towards going in deep about these chapters. Thank you. Thank you very much. [bell] [music] >> [music] [music]