According to the Centers for Disease Control and Prevention (CDC), an individual with prediabetes has a blood sugar level higher than normal, but not high enough for a diagnosis of diabetes. He or she is at higher risk for developing type 2 diabetes and other serious health problems, including heart disease, and stroke. Without lifestyle changes to improve their health, 15% to 30% of people with prediabetes will develop type 2 diabetes within five years.
According to a new study, individuals with prediabetes are at risk for kidney damage, manifested by for hyperfiltration (increased filtration rate) and albuminuria (protein in the urine). The findings were published online on December 9 in the American Journal of Kidney Diseases by researchers at UiT The Arctic University of Norway, Tromsø, Norway.
The researchers note that the role of prediabetes as a risk factor for hyperfiltration and albuminuria in individuals who do not develop diabetes is unclear. The lack of evidence is mainly due to the difficulty of accurately assessing the glomerular filtration rate (GFR) in the near-normal range of GFR. Therefore, they conducted a study to investigate whether prediabetes is an independent risk factor for glomerular hyperfiltration and high-normal urinary albumin-creatinine ratio (ACR). This was accomplished by using measured GFR (mGFR) rather than estimated GFR.
The study group comprised 1,261 individuals without diabetes from the general population aged 50 to 62 years. A prospective study was conducted that was based on the Renal Iohexol Clearance Survey in Tromsø 6 (RENIS-T6) and the RENIS Follow-Up Study. The average observation time was 5.6 years. Prediabetes defined by fasting glucose and hemoglobin A1c according to levels suggested by the American Diabetes Association (preDMADA) and the International Expert Committee of 2009 (preDMIEC). The main outcome measurement was a change in mGFR (hyperfiltration defined as mGFR above the 9th percentile adjusted for age, sex, weight, and height; and high-normal ACR (more than 10 mg/g) at follow-up.
The investigators found that baseline fasting glucose, hemoglobin A1c, and both definitions of prediabetes were predictors of higher mGFR at follow-up and lower annual mGFR decline. Participants with preDMIEC had a 95% increased risk of hyperfiltration and a 83% increased risk of high-normal at follow-up. The researchers adjusted for cardiovascular risk factors including blood pressure at baseline and change in use of antihypertensive medication between baseline and follow-up.
The authors note that a limitation of the study was that it comprised only middle-aged white patients and that, at present, there is no consensus on how to define glomerular hyperfiltration. However, they concluded that their findings suggest an independent role of prediabetes in the development of glomerular hyperfiltration and albuminuria. Thus, prediabetes might be a target for early treatment to prevent chronic kidney disease in chronic hyperglycemia.