Prediabetes is a condition defined as having blood glucose levels above normal but below the defined threshold of diabetes. Various organizations have a different cut off value for blood glucose levels to diagnose an individual as prediabetic.
Following is a table showing the different values of blood glucose level for diagnosis of insulin resistance & diabetes:
| Diagnosis | Fasting plasma glucose levels (mg/dl) | 2hr postprandial plasma glucose level | HbA1c |
|---|---|---|---|
| Normal | <99 | <139 | <5.7 % |
| Prediabetes | 100-125 | 140-199 | 5.7- 6.4 % |
| Diabetes | >126 | >200 | > 6.5 % |
The worldwide prevalence of IGT in 2010 was estimated to be 343 million & the International Diabetes Federation projects an increase in prevalence of prediabetes to 471 million globally by 2035.
The development of prediabetes is multistage. In the first stage, there is insulin resistance but this is compensated by increased insulin secretion & beta cell mass of the pancreas. The second stage is where the beta cells are unable to cope with the insulin resistance thus leading to unstable fasting or postprandial glucose levels. In the third stage, the glucose levels start to rise rapidly as the pancreatic beta cells cannot make up for the insulin resistance. This final stage then gradually terminates into full blown diabetes.
Progression to Diabetes
The risk of progression to diabetes is greater in cases with both Impaired fasting glucose and Impaired glucose tolerance compared with isolated IFG or isolated IGT alone. Apart from the degree of insulin resistance and deficiency of insulin secretion, the risk of progression to diabetes depends on other diabetes risk factors, such as family history, age, obesity, or history of gestational diabetes or polycystic ovary syndrome.
If insulin secretion would be able to compensate for insulin resistance, no observable changes in glucose levels would occur which means that, by definition, β-cell dysfunction is already present in the prediabetic phase itself. Studies using different measures of β-cell function have reported severely abnormal insulin secretion in prediabetic people. Also autopsy studies report a 50% decrease in β-cell volume among those with glucose values within the IFG range.
Various complications are associated with prediabetes, a few of which include nephropathy, neuropathy, retinopathy, erectile dysfunction & microvascular diseases.
Treatment goals
For those diagnosed with prediabetes, the main focus of treatment should be restoring euglycemia, because research shows that restoring normoglycemia during prediabetes and early diabetes can produce lasting remission. The cornerstone of diabetes prevention is lifestyle modification, with evidence of a 40%–70% relative risk reduction.
Lifestyle interventions
Increase in physical activity levels & making dietary changes can decrease the obesity levels thereby improving the chances of conversion from prediabetes to diabetes. According to the Diabetes prevention program, every 1 kg decrease in weight, there is a drop-in risk of developing diabetes by 16%. This study emphasized weight reduction greater than 5 percent, limiting total fat intake to less than 30 percent of energy intake, saturated-fat intake less than 10 percent of energy intake, fiber intake greater than or equal to 15 g per 1000 kcal, and exercise greater than 4 h/week.
References:
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Bansal, N. (2015) ‘Prediabetes diagnosis and treatment: A review’, World Journal of Diabetes, 6(2), p. 296. doi: 10.4239/WJD.V6.I2.296.
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Butler, A. E. et al. (2003) ‘Beta-cell deficit and increased beta-cell apoptosis in humans with type 2 diabetes’, Diabetes, 52(1), pp. 102–110. doi: 10.2337/DIABETES.52.1.102.
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Khetan, A. K. and Rajagopalan, S. (2018) ‘Prediabetes’, Canadian Journal of Cardiology, 34(5), pp. 615–623. doi: 10.1016/J.CJCA.2017.12.030.
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Muhammad A A.G et.al. (2006) ‘Contributions of beta-cell dysfunction and insulin resistance to the pathogenesis of impaired glucose tolerance and impaired fasting glucose’, Diabetes care, 29(5), pp. 1130–1139. doi: 10.2337/DIACARE.2951130.
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Saito, T. et al. (2011) ‘Lifestyle modification and prevention of type 2 diabetes in overweight Japanese with impaired fasting glucose levels: a randomized controlled trial’, Archives of internal medicine, 171(15), pp. 1352–1360. doi: 10.1001/ARCHINTERNMED.2011.275.
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Tabák, A. G. et al. (2012) ‘Prediabetes: A high-risk state for developing diabetes’, Lancet, 379(9833), p. 2279. doi: 10.1016/S0140-6736(12)60283-9.
