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The evidence of GI & GL


1. A meta-analysis of prospective cohort studies understanding impact of glycaemic index and glycaemic load in the risk of type 2 diabetes (Dong, Zhang, Zhang, & Qin, 2011).

Thirteen studies of dietary GI or GL related to diabetes risk were included. The summary RR of type 2 diabetes for the highest category of the GI compared with the lowest was 1.16. For the GL, the summary RR was 1.20. The study came to conclusions that reducing the intake of high GI foods may bring benefits for diabetes prevention,

2. A meta-analysis (Brand-Miller, Hayne, Petocz, & Colagiuri, 2003) comprised 14 studies and 356 subjects; 203 with T1DM and 153 with T2DM. The average GI of the high GI diet was 83 and the average GI of the low diet was 65. The mean difference in units was -0.33% (DCCT) and after 12 weeks the average was -0.4% (c.5 mmol/mol).

3. A third meta-analysis observed impact on GI and also identified impact on blood lipids; - total cholesterol average reductions of 6.4mg/dL and LDL 5.5 mg/dL with a dose dependent effect identified. The low GI diets had a statistically significant impact in reducing weight for obese individuals, but not for those of normal weight or overweight category (Zafar, et al., 2019).

4. Although NICE supports low glycaemic index in its statements for dietary recommendations (NICE, 2022) it explicitly states it does not endorse a low-carbohydrate diet.

In review of resources that it had previously endorsed from Dr David Unwin and retracting them, it states, “our diabetes guideline clearly recommends that people should follow a healthy balanced diet that contains, but is not limited to, eating low glycaemic index sources of carbohydrates.

We have therefore taken the decision to revoke our endorsement of Dr Unwin’s resource and have removed the link to it from NICE’s website”.

5. Dr David Unwin has studied glycaemic-related interventions in NHS General Practice interventions. Average body weight fell by 9kg, waist circumference by 15cm, reduction in hba1c by 10mmol/L (19%) and 5% reduction in total cholesterol and Dr Unwin has estimated a saving of £45,000 of prescribing costs in a single practice (Unwin, Livesey, & Haslam, It is the glycaemic response to, not the carbohydrate content of food that matters in diabetes and obesity: The glycaemic index revisited, 2016).


1. Dong, J. Y., Zhang, L., Zhang, Y. H., & Qin, L. Q. (2011). Dietary glycaemic index and glycaemic load in relation to the risk of type 2 diabetes: a meta-analysis of prospective cohort studies. . British Journal of Nutrition, 106(11), 1649-1654.

2. Brand-Miller, J., Hayne, S., Petocz, P., & Colagiuri, S. (2003). Low–glycemic index diets in the management of diabetes: a meta-analysis of randomized controlled trials. Diabetes care, 26(8), 2261-2267

3. Zafar, M. I., Mills, K. E., Zheng, J., Regmi, A., Hu, S. Q., Gou, L., & L, a. C. (2019). Low-glycemic index diets as an intervention for diabetes: a systematic review and meta-analysis. The American journal of clinical nutrition, 110(4), 891-902

4. NICE. (2022). National Insitute for Clinical Excellence - Type 2 Diabetes in adults: management. Retrieved June 2022, from

5. Unwin, D., Livesey, G., & Haslam, D. (2016). It is the glycaemic response to, not the carbohydrate content of food that matters in diabetes and obesity: The glycaemic index revisited. . Journal of Insulin Resistance, 1(1), 1-9

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