PracticeUpdate Diabetes June 2019

EDITOR’S PICKS 5

Risk Factors for Retinopathy in Type 1 Diabetes Take-home message • In this study of participants in the DCCT/EDIC studies, retinopathy risk factors were evaluated using data from more than 30 years of follow-up. The rate of ocular events per 1000 person-years was 12 for proliferative diabetic retinopathy, 14.5 for clinically significant macular edema, and 7.6 for ocular surgeries. The greatest risk factors for proliferative diabetic retinopathy were higher mean HbA1c levels, longer duration of type 1 diabetes, elevated albumin excretion rate, and higher average diastolic blood pressure. Risk factors for clinically signifi- cant macular edema were higher average HbA1c levels, longer duration of type 1 diabetes, older age, and higher average diastolic blood pressure. Risk factors for ocular surgeries were higher average HbA1c levels, older age, and longer diabetes duration. • HbA1c levels, elevated albumin excretion rate, and higher average diastolic blood pressure are modifiable risk factors, in addition to glycemic control, associated with retinopathy progression. Abstract OBJECTIVE The Diabetes Control and Complications Trial (DCCT) demonstrated that intensive therapy reduced the development and progression of retinopathy in type 1 diabetes (T1D) compared with con- ventional therapy. The Epidemiology of Diabetes Interventions and Complications (EDIC) study observational follow-up showed persis- tent benefits. In addition to glycemia, we now examine other potential retinopathy risk factors (modifiable and nonmodifiable) over more than 30 years of follow-up in DCCT/EDIC. RESEARCH DESIGN AND METHODS The retinopathy outcomes were prolif- erative diabetic retinopathy (PDR), clinically significant macular edema (CSME), and ocular surgery. The survival (event-free) probability was estimated using the Kaplan-Meier method. Cox proportional hazards models assessed the association between risk factors and subsequent risk of retinopathy. Both forward- and backward-selection approaches determined the multivariable models. RESULTS Rate of ocular events per 1,000 person-years was 12 for PDR, 14.5 for CSME, and 7.6 for ocular surgeries. Approximately 65%, 60%, and 70% of participants remained free of PDR, CSME, and ocular surgery, respectively. The greatest risk factors for PDR in descend- ing order were higher mean HbA1c, longer duration of T1D, elevated albumin excretion rate (AER), and higher mean diastolic blood pres- sure (DBP). For CSME, risk factors, in descending order, were higher mean HbA1c, longer duration of T1D, and greater age and DBP, and for ocular surgeries were higher mean HbA1c, older age, and longer duration of T1D. CONCLUSIONS Mean HbA1c was the strongest risk factor for the progres- sion of retinopathy. Although glycemic control is important, elevated AER and DBP were other modifiable risk factors associated with the progression of retinopathy. Risk Factors for Retinopathy in Type 1 Diabetes: The DCCT/ EDIC Study. Diabetes Care 2019 Mar 04;[EPub Ahead of Print], DP Hainsworth, I Bebu, LP Aiello, et al. www.practiceupdate.com/c/80729 Diabetes Care

Abstract BACKGROUND Lifestyle interventions can delay the onset of type 2 dia- betes in people with impaired glucose tolerance, but whether this leads subsequently to fewer complications or to increased longevity is uncer- tain. We aimed to assess the long-term effects of lifestyle interventions in people with impaired glucose tolerance on the incidence of diabetes, its complications, and mortality. METHODS The original study was a cluster randomised trial, started in 1986, in which 33 clinics in Da Qing, China, were randomly assigned to either be a control clinic or provide one of three interventions (diet, exercise, or diet plus exercise) for 6 years for 577 adults with impaired glucose toler- ance who usually receive their medical care from the clinics. Subsequently, participants were followed for up to 30 years to assess the effects of intervention on the incidence of diabetes, cardiovascular disease events, composite microvascular complications, cardiovascular disease death, all- cause mortality, and life expectancy. FINDINGS Of the 577 participants, 438 were assigned to an intervention group and 138 to the control group (one refused baseline examination). After 30 years of follow-up, 540 (94%) of 576 participants were assessed for outcomes (135 in the control group, 405 in the intervention group). During the 30-year follow-up, compared with control, the combined inter- vention group had a median delay in diabetes onset of 3·96 years (95% CI 1·25 to 6·67; p=0·0042), fewer cardiovascular disease events (hazard ratio 0·74, 95% CI 0·59-0·92; p=0·0060), a lower incidence of microvascular complications (0·65, 0·45-0·95; p=0·025), fewer cardiovascular disease deaths (0·67, 0·48-0·94; p=0·022), fewer all-cause deaths (0·74, 0·61-0·89; p=0·0015), and an average increase in life expectancy of 1·44 years (95% CI 0·20-2·68; p=0·023). INTERPRETATION Lifestyle intervention in people with impaired glucose tol- erance delayed the onset of type 2 diabetes and reduced the incidence of cardiovascular events, microvascular complications, and cardiovascu- lar and all-cause mortality, and increased life expectancy. These findings provide strong justification to continue to implement and expand the use of such interventions to curb the global epidemic of type 2 diabetes and its consequences. Morbidity and Mortality After Lifestyle Intervention for People With Impaired Glucose Tolerance: 30-year Results of the Da Qing Diabe- tes Prevention Outcome Study. Lancet Diabetes Endocrinol 2019 Apr 26;[EPub Ahead of Print], Q Gong, P Zhang, J Wang, et al. www.practiceupdate.com/c/82928

VOL. 3 • NO. 2 • 2019

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