Understanding the difference between added sugar and blood glucose is a useful starting point for anyone learning about insulin resistance, prediabetes or type 2 diabetes. Added sugar affects more than body weight. High intake—particularly from sugar-sweetened beverages—has been linked to cardiovascular disease, insulin resistance, fatty liver, abnormal blood lipids and higher cardiovascular mortality.[1,3–6]
Blood glucose also matters across the metabolic spectrum. The risk associated with glucose does not begin only after someone receives a diabetes diagnosis. Large population and genetic analyses have connected higher glucose levels with damage involving the eyes, nerves, kidneys and cardiovascular system.[2]
These are related but distinct issues:
- Added sugar intake describes sugar introduced during manufacturing, preparation or at the table.
- Blood glucose is the amount of glucose circulating in the blood and reflects food intake, liver glucose production, insulin sensitivity, medication, sleep, stress and other factors.
- Refined starches are not labeled as added sugar, but they can be rapidly digested into glucose and may also produce a large glycemic response.
Understanding those distinctions makes the practical solution clearer: reduce concentrated sugar and refined carbohydrate exposure while improving the overall metabolic context.
Added sugar and cardiovascular mortality
The original Toward Health article cited a nationally representative analysis of U.S. adults using NHANES dietary data and linked mortality records.[1]
The prospective analysis included 11,733 adults followed for a median of 14.6 years, during which 831 cardiovascular deaths occurred. Compared with people consuming less than 10% of daily calories from added sugar, those consuming 10%–24.9% had a 30% higher adjusted risk of cardiovascular death. Those consuming at least 25% had a 175% higher adjusted risk.[1]
The relationship persisted after adjustment for demographic, behavioral and clinical factors. Because this was an observational cohort, it identifies a strong dose-related association rather than proving that added sugar alone caused every event. Controlled feeding studies nevertheless provide a plausible biological bridge between sugar exposure and cardiometabolic risk.[3–5]
What controlled trials show
The liver can respond within weeks
In a double-blind randomized trial, 94 healthy men consumed beverages containing fructose, sucrose or glucose—or avoided sugar-sweetened beverages—for seven weeks. The beverages supplied 80 grams of sugar per day.[3]
Fructose- and sucrose-sweetened beverages approximately doubled basal hepatic de novo lipogenesis compared with the control group. In plain language, the liver increased its production of new fatty acids. The glucose-sweetened beverage did not produce the same change in that trial.[3]
Sucrose and high-fructose corn syrup both affected metabolic health
A separate double-blind intervention assigned 75 young adults to beverages sweetened with sucrose, high-fructose corn syrup or aspartame. The sugar-sweetened beverages supplied 25% of estimated daily energy requirements for 16 days.[4]
Compared with the aspartame group, sucrose increased liver fat and both sucrose and high-fructose corn syrup reduced measures of insulin sensitivity. The sugar-containing beverages also increased circulating lipids, lipoproteins and uric acid. The changes remained significant after adjustment for body-weight change, and the investigators found no meaningful advantage of sucrose over high-fructose corn syrup.[4]
In an earlier 10-week controlled intervention in adults with overweight or obesity, fructose-sweetened beverages increased visceral fat, hepatic fat production, post-meal triglycerides and several atherogenic lipoprotein measures while decreasing insulin sensitivity. Glucose-sweetened beverages produced similar weight gain but a different metabolic pattern.[5]
Together, these trials show that concentrated liquid sugar can alter liver fat production, insulin sensitivity and cardiovascular risk markers even before a person develops overt diabetes.
Higher glucose and vascular complications
The second original Disciple citation examined glucose levels and vascular disease using data from 117,193 Danish adults, with additional genetic analyses involving large international datasets.[2]
In the Mendelian-randomization analysis, each genetically predicted 1 mmol/L increase in glucose was associated with higher risk of:
- Retinopathy: risk ratio 2.01
- Neuropathy: risk ratio 2.15
- Diabetic nephropathy: risk ratio 1.58
- Myocardial infarction: risk ratio 1.49
The genetic analysis did not confirm every observational association: evidence was not conclusive for peripheral arterial disease and did not support an effect on reduced estimated glomerular filtration rate as defined in the study. The more specific findings for retinopathy, neuropathy, diabetic nephropathy and myocardial infarction nevertheless reinforce that glucose exposure affects both small and large blood vessels.[2]
Sugar-sweetened beverages and heart disease
Long-term cohort data point in the same direction. In 42,883 men followed for 22 years, the highest quartile of sugar-sweetened-beverage intake was associated with a 20% higher adjusted risk of coronary heart disease than the lowest quartile. Higher intake was also associated with higher triglycerides and inflammatory markers and lower HDL cholesterol.[6]
A 2024 analysis combined 65,730 women from the Nurses’ Health Study with 39,418 men from the Health Professionals Follow-up Study. Over more than three million person-years, researchers documented 13,269 cardiovascular events. Consuming at least two sugar-sweetened beverages per day was associated with a 21% higher cardiovascular risk than rarely or never consuming them. Meeting physical-activity guidelines did not eliminate the association.[7]
Where the largest exposures hide
The most concentrated sources are often easy to consume quickly and provide little satiety:
- Soda, sweet tea, lemonade and energy drinks
- Sweetened coffee drinks
- Juice drinks and many bottled smoothies
- Candy, pastries, desserts and sweetened cereals
- Sweetened yogurt and snack bars
- Sauces, dressings and packaged foods with added sugars
Food labels report total sugars and added sugars separately. A product can also produce a substantial glucose response through refined starch even when the added-sugar number appears modest.
A practical low-carbohydrate strategy
Reducing added sugar is a high-value first step. A low-carbohydrate approach goes further by reducing the combined glycemic burden from sugar and rapidly digested starch.
A practical plan can emphasize:
- Water, mineral water, unsweetened coffee or tea in place of sugar-sweetened drinks
- Protein-centered meals that improve satiety
- Minimally processed foods instead of refined snacks and desserts
- Deliberate label reading for sauces, drinks and packaged foods
- Lower-sugar alternatives chosen for the individual’s metabolic goals and tolerance
- Tracking glucose when it will meaningfully guide food or medication decisions
The goal is not simply to exchange table sugar for unlimited refined starch. The goal is to reduce repeated glucose and insulin demand while building meals that are satisfying and sustainable.
Work with your medical team
People using insulin, sulfonylureas or other medications that can cause hypoglycemia may need medication adjustment when carbohydrate intake falls. Blood-pressure medication can also require reassessment as metabolic health improves.
Seek individualized guidance during pregnancy, with significant kidney or liver disease, with a history of disordered eating, or when symptoms suggest undiagnosed diabetes. Excessive thirst, frequent urination, unexplained weight loss, vomiting, confusion or markedly elevated glucose requires prompt medical evaluation.
The takeaway
Added sugar—especially in beverages—is associated with cardiovascular events and mortality, while controlled trials show that concentrated sugar can worsen liver fat production, insulin sensitivity and circulating risk markers.[1,3–7]
Higher blood glucose is also connected to microvascular and macrovascular injury.[2] Removing added sugar and reducing refined carbohydrate exposure are therefore practical steps for improving heart, liver and metabolic health.
References
-
Yang Q, Zhang Z, Gregg EW, Flanders WD, Merritt R, Hu FB. Added sugar intake and cardiovascular diseases mortality among US adults. JAMA Intern Med. 2014;174(4):516–524. doi: 10.1001/jamainternmed.2013.13563.
-
Emanuelsson F, Marott S, Tybjærg-Hansen A, Nordestgaard BG, Benn M. Impact of Glucose Level on Micro- and Macrovascular Disease in the General Population: A Mendelian Randomization Study. Diabetes Care. 2020;43(4):894–902. doi: 10.2337/dc19-1850.
-
Geidl-Flueck B, Hochuli M, Németh Á, et al. Fructose- and sucrose- but not glucose-sweetened beverages promote hepatic de novo lipogenesis: A randomized controlled trial. J Hepatol. 2021;75(1):46–54. doi: 10.1016/j.jhep.2021.02.027.
-
Sigala DM, Hieronimus B, Medici V, et al. Consuming Sucrose- or HFCS-sweetened Beverages Increases Hepatic Lipid and Decreases Insulin Sensitivity in Adults. J Clin Endocrinol Metab. 2021;106(11):3248–3264. doi: 10.1210/clinem/dgab508.
-
Stanhope KL, Schwarz JM, Keim NL, et al. Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans. J Clin Invest. 2009;119(5):1322–1334. doi: 10.1172/JCI37385.
-
de Koning L, Malik VS, Kellogg MD, Rimm EB, Willett WC, Hu FB. Sweetened beverage consumption, incident coronary heart disease, and biomarkers of risk in men. Circulation. 2012;125(14):1735–1741. doi: 10.1161/CIRCULATIONAHA.111.067017.
-
Pacheco LS, Tobias DK, Li Y, et al. Sugar-sweetened or artificially-sweetened beverage consumption, physical activity, and risk of cardiovascular disease in adults: A prospective cohort study. Am J Clin Nutr. 2024;119(3):669–681. doi: 10.1016/j.ajcnut.2024.01.001.
