Publication Date

2013-07-18

Availability

Open access

Embargo Period

2013-07-18

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Psychology (Arts and Sciences)

Date of Defense

2013-06-03

First Committee Member

Maria M. Llabre

Second Committee Member

Neil Schneiderman

Third Committee Member

Ronald Goldberg

Fourth Committee Member

Marc Gellman

Fifth Committee Member

Armando Mendez

Abstract

Reduced glomerular filtration rate and increased albuminuria often develop in Type 2 Diabetes Mellitus (T2DM) and are predictive of chronic kidney and cardiovascular disease. Risk for renal disease in T2DM has been associated with cardiometabolic risk factors including, hypertension, dyslipidemia, and hyperglycemia. Weight loss is associated with improved outcomes in T2DM patients with existing renal disease and may also reduce risk in patients without renal disease via reduction of cardiometabolic risk factors. The aims of this study were (1) to examine the effects of a behavioral weight loss intervention on renal outcomes in T2DM patients without evidence of renal disease, and (2) to determine if change in renal outcomes is related to key demographic and cardiometabolic risk factors. A sample of 111 T2DM patients (mean age = 54.81 years, 28.8% male) was recruited from community health clinics and by "word-of-mouth" and randomized to receive a 17-session lifestyle intervention or usual care (control). Eligible participants were overweight or obese, reported significant symptoms of depression, and had no evidence of existing renal or cardiovascular disease at screening. Demographic, psychosocial, anthropometric, blood and urine measures were collected at baseline and repeated at 6-months and 12-months post randomization. Primary outcomes included weight, depressive symptoms, glycosylated hemoglobin (HbA1c), creatinine-based estimated glomerular filtration rate (eGFRCR), cystatin c and creatinine-based eGFRCY-CR, (estimated using Chronic Kidney Disease Epidemiology Collaboration formulas), and urinary albumin to creatinine ratio (UACR). Relative to usual care, the intervention resulted in significant increases in eGFRCY-CR (B= .331, SE = .142, p < .05), as well as significant decreases in weight (B = -.320, SE = .125, p < .01), depressed affect (B = -.993, SE = .228, p < .001), and HbA1c (B = -.068, SE = .030, p < .05). There was no effect of intervention on eGFRCR (B = -.146, SE = .119, p = .219) or UACR (B = .228, SE = .336, p = .497). The model estimated normative change in eGFRCY-CR was significant (B = .468, SE = .200, p < .05) and non-linear, indicating a change in direction of the slope after 6 months and an overall decline. Normative change in eGFRCR was not significant, (B= -.146, SE = .119, p > .05). Independent predictors of rate of change in eGFRCR were UACR, systolic blood pressure, high density lipoprotein cholesterol (HDL-C) and eGFR at baseline. The intervention effect on eGFR was related to UACR and HDL-C, HbA1C and triglycerides at baseline. UACR increased among all participants (B= .460, SE = .163, p < .05), and was related to UACR at baseline. Additional cardiometabolic risk factors were not related to change in UACR. Behavioral weight loss strategies may be implemented to preserve renal function among T2DM patients and prevent or delay the onset of renal disease in this population. Such strategies may be particularly effective for patients with dyslipidemia and hyperglycemia, and less effective for patients with elevated albumin excretion. Future studies should identify potential mediators of beneficial effects.

Keywords

Type 2 Diabetes; weight loss intervention; diabetic nephropathy; randomized controlled trial

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