Albuminuria is a marker of kidney damage and endothelial dysfunction [3]. Measurement of the spot urinary albumin-to-creatinine ratio is recommended in all patients with T2DM to screen for diabetic kidney disease [4], which may be present at the diagnosis of T2DM [5]. Much evidence demonstrates that albuminuria is associated with cardiovascular mortality and is a strong determinant of chronic kidney disease progression regardless of the presence of metabolic disease [3]. Therefore, albuminuria is considered a good biomarker of cardiovascular, kidney, and metabolic diseases to identify and monitor the disease trajectory [3]. There are well-established interactions of heart and kidney dysfunction, which can cause cardiorenal syndrome and cardiometabolic disease between heart and metabolic risk factors. These interactions stem from excess and dysfunctional adipose tissue, a condition called obesity [3]. Such adipose tissue can cause inflammation and insulin resistance, resulting in metabolic risk factors such as diabetes mellitus (DM) [3]. Besides markers of target organ damage in cardiovascular disease and chronic kidney disease, albuminuria is associated with obesity and insulin resistance, which occur at an early stage of cardiovascular and metabolic diseases [3]. Obesity affects the kidneys through various mechanisms such as intrarenal hemodynamics, the renin-angiotensin-aldosterone system, and potentially augmented levels of pro-inflammatory molecules [6]. The UK Biobank study showed that the occurrence of albuminuria is increasing in patients with obesity [6], and patients with morbid obesity and albuminuria exhibit significantly improved albuminuria after weight loss following bariatric surgery [7]. Therefore, obesity is considered a risk factor for albuminuria independent of DM [3]. Insulin resistance caused by obesity leads to endothelial dysfunction and impaired vasodilation. It develops due to loss of glomerular basement membrane integrity and impaired proximal tubular albumin resorption [3]. Insulin resistance plays a major role in the pathogenesis of T2DM and precedes the diagnosis of DM [8]. In the United Kingdom Prospective Diabetes Study, 7.3% of participants had microalbuminuria at diagnosis of DM [9]. Mykkänen et al. [8] reported that microalbuminuria predicted the development of DM independently of blood pressure in a prospective population-based study of nondiabetic elderly subjects living in eastern Finland. Based on these studies, albuminuria may be a marker to assess cardiovascular, kidney, and metabolic health and to detect T2DM.

A study by Kim et al. [10] supports this possibility. They studied whether albuminuria detected by dipstick urinalysis predicts T2DM using data obtained from the Korean National Health Insurance Service database between 2009 and 2012. They screened 5,383,779 subjects aged ≥20 and <40 years without a history of prediabetes or DM. Among them, 1.2% of subjects developed early-onset DM, and albuminuria was significantly associated with early-onset T2DM after adjustment for age, sex, anthropometric data, physical exercise status, serum glucose, and total cholesterol. The risk of early-onset T2DM was higher in subjects with more components of metabolic syndrome [10]. This study suggests that albuminuria starts at a very early stage of T2DM with obesity and is a sign of metabolic abnormalities. However, there remain concerns about screening for albuminuria to detect T2DM. Dipstick urinalysis has the advantages of low cost and widespread availability and affordability, so there are many reasons why albuminuria may be detected via dipstick urinalysis in the general population. However, it is semiquantitative and has low sensitivity. In addition, there is uncertainty about how broadly and frequently patients should be screened and how frequently albuminuria should be monitored [3]. Despite these limitations, albuminuria is a good marker of metabolic disease, and dipstick urinalysis, which is broadly used in clinical settings, is a good option for screening. In summary, albuminuria, which indicates kidney damage, may develop as a result of obesity, a significant risk factor for T2DM and an early stage in the disease’s progression. Therefore, patients with albuminuria, especially those with multiple metabolic risk factors, must be closely monitored for the development of T2DM.