A new study in Japan researched the association between HbA1c levels and body mass index, and its effect on diabetic kidney disease prevention.
Diabetic kidney disease (DKD) is one of the many complications due to diabetes. Diabetes can cause damage to the kidneys over time if not controlled, which makes it difficult for the kidneys to filter blood and waste in the body. As a result of this impaired filtration, the waste can build up in the body and cause damage to other organs. Many people do not realize how detrimental this disease is because it happens slowly over time. If diabetic kidney disease is not controlled, then it can lead to end-stage renal disease (ESRD), which would require hemodialysis. Obesity is another factor that has been under fire for being a risk factor for kidney disease. Obesity is defined as having a body mass index of at least 25 kg/m^2 in Japan. There is a belief that controlling BMI and glucose can prevent diabetic kidney disease, which is why this study was conducted.
This study was a retrospective cohort study conducted in Japan. Patients that were included in this study had to be diagnosed with type 2 diabetes and had to visit the diabetes clinic at Kawasaki Medical School Hospital between 2000 and 2018. These patients were studied for two years. Patients with diabetes that were younger than 20 years old were excluded from this study. Microangiopathy is a disease affecting the small blood vessels in the body. Participants were excluded from the study if they had microangiopathy at any point during the study. The participants that were included in the study were split into two groups based on HbA1c value. Those with an HbA1c of less than 7% were classified as the “controlled” group, whereas the participants with an HbA1c of at least 7% were categorized as the “uncontrolled” group. The participants were also put into groups based on their BMI: “non-overweight” for those with a BMI of less than 25 kg/m^2 and “overweight” for those with a BMI of at least 25 kg/m^2.
The mean age of the participants at the beginning of the study was 61 years old, with an average follow-up period of 5.96 years. After making adjustments for gender, age, diabetes duration, and medications used for lipid and hypertension control, the hazard ratio for developing diabetic kidney disease was 1.20 in those with an elevated HbA1c and 1.03 in those with a high BMI. Both values are statistically significant, and the results show that the risk of developing DKD was more strongly associated with an elevated HbA1c compared to obesity.
Tight glycemic control was shown to be important in preventing neuropathy and retinopathy. Both factors, however, are essential to control to avoid DKD. This study showed that the group of patients who had a high HbA1c level and overweight had the highest hazard ratio of developing diabetic kidney disease out of all four groups. This further proves the fact that both maintaining a healthy BMI and controlling HbA1c are vital in preventing the development of DKD.
There were a handful of limitations that this study presented. One of the limitations was that the age of the patient could have affected which medications were chosen for diabetes, hypertension, and hyperlipidemia. These different choices of drugs could have ultimately played a part in whether a person would be diagnosed with DKD or not. Another limitation was the limited number of participants in the study, as well as a significant difference in group sizes between the four groups. Furthermore, social factors such as smoking and diet were not taken into consideration in this study, which could have played a significant role in the onset of DKD.
- HbA1c and BMI are important factors to control to prevent diabetic kidney disease
- The prevention of diabetic kidney disease can prevent further complications from occurring, such as nerve and eye associated diseases.
- Further studies need to be conducted to rule out other confounding variables that could have affected the progression of DKD in this study.
More on preventing kidney failure from Dr. George Bakris
Nakanishi, Shuhei, and et al. “Comparison of HbA1c Levels and Body Mass Index for Prevention of Diabetic Kidney Disease: A Retrospective Longitudinal Study Using Outpatient Clinical Data in Japanese Patients with Type 2 Diabetes Mellitus.” Diabetes Research and Clinical Practice, Elsevier B.V., 5 Aug., 2019, https://doi.org/10.1016/j.diabres.2019.107807.
Joel John, Pharm.D. Candidate, Florida A&M University, College of Pharmacy & Pharmaceutical Sciences