A higher level of coffee consumption in type 2 diabetics significantly reduces the rate of decline in estimated glomerular filtration rate
A greater coffee consumption in those with type 2 diabetes is significantly associated with a reduction in the rate of decline in the estimated glomerular filtration rate (eGFR). This was the key finding from a prospective study by researchers from the Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Chronic kidney disease (CKD) is a non-communicable disease and which usually develops as a consequence of diabetes and hypertension. Disease severity in CKD can be assessed by a low serum creatinine-based eGFR, which indicates excretory kidney function and by a raised urinary albumin. Lifestyle management is deemed to be a fundamental aspect of diabetes care and this encompasses self-management education and support, medical nutrition therapy, physical activity, smoking cessation counselling and psychosocial care. Nutritional therapy, however, does not just include what foods to eat but also what should be drunk. One commonly consumed beverage is coffee and a higher coffee consumption, as well as green tea, has been found to be associated with a reduction in all-cause mortality, particularly in patients with type 2 diabetes. Furthermore, some data suggests that a higher coffee consumption is associated with lower risk for incident CKD. Nevertheless, this finding is not consistent, with other work undertaken in men, find that there was no significant association between coffee consumption and CKD.
What remains unclear though, is if a higher level of coffee consumption in patients with type 2 diabetes would reduce the decline in kidney function. For the present study, the Japanese team carried out a prospective study of adult diabetic patients attending diabetic clinics throughout the country. They carried out a dietary survey which asked about coffee consumption but also had access to clinical measurements such as blood pressure and eGFR taken at the clinics. Coffee consumption was recorded as none, less than 1 cup/day, one cup/day or two or more cups/day. The primary outcome was set as a decline in eGFR to <60 mL/min/ 1.73 m2, based on two consecutive measures of eGFR during the follow-up period.
Coffee consumption and decline in eGFR rate
In total, 3,805 patients with type 2 diabetes and a mean age of 64.2 years (44.4% female) and eGFR ≥60ml/min/1.73 m2 were followed-up for a median of 5.3 years.
During the period of follow-up, 840 participants experienced a decline in eGFR of < 60 mL/min/1.73 m2. Using multivariate analysis, the researched found that compared to those who drank no coffee, the adjusted hazard ratio (aHR) for a decline in eGFR associated with drinking less than one cup/day was 0.77 (95% CI 0.63 – 0.97) and this increased slightly to 0.75 (95% CI 0.62 – 0.91) for those drinking two or more cups/day.
The mean eGFR change per year was -2.16ml/min/1.73 m2 with no coffee consumption, and -1.78ml/min/1.73 m2 with two or more cups per day (p for trend 0.03).
There was also no significant effect on coffee drinking and the decline in eGFR based on age, gender, body mass index, smoking status, those who exercised regularly or blood pressure.
The authors concluded that coffee consumption is significantly associated with a lower risk of a decline in eGFR, which suggested a progressive impairment in renal function, in patients with type 2 diabetes.
Komorita Y et al. Relationship of coffee consumption with a decline in kidney function among patients with type 2 diabetes: The Fukuoka Diabetes Registry J Diabetes Investig 2022