June 18, 2015
Abstract: U.S. clinicians appear to guide HIV patients to appropriate glucose targets as often as they do patients without HIV, but only about one half of patients meet the strictest glucose goal. Glucose targets may need to be tighter for some -- but not all -- HIV-positive people than for the general population. Reaching glucose targets cuts the risk of vascular complications. Treating HIV-positive people with high glucose should include active management of lipids and hypertension plus regular retinal and foot exams. Clinicians have four tools to screen for diabetes and monitor treatment response in people with high glucose: fasting blood glucose, hemoglobin A1c (HbA1c), the oral glucose tolerance test (OGTT), and random glucose. Several studies show that HbA1c underestimates blood glucose in people with HIV and some experts recommend avoiding it to screen for diabetes in HIV populations. U.S. guidelines say the role of OGTT in HIV-positive people is "uncertain," but it may be appropriate for people with multiple risk factors.
How often do U.S. clinicians meet American Diabetes Association (ADA) treatment goals in HIV-positive people with diabetes? At two big urban HIV centers in Chicago1 and New York,2 HIV providers hit glycemic goals in one half to three quarters of patients -- depending on the hemoglobin A1c (HbA1c) target -- close to rates reported in the general population (Table 1).
But only about half of diabetic HIV patients in these cohorts met ADA blood pressure goals, and only one third nailed triglyceride targets. Clinicians at both sites admitted they may have overestimated proportions of on-target patients because they eliminated people with fewer visits or hemoglobin A1c measurements. And neither survey looked at how rigorously clinicians screen HIV patients for high glucose, insulin resistance, or diabetes -- or how well they manage prediabetes.
Keen attention to glucose abnormalities and their control in people with HIV assumes growing importance as these complications loom larger in HIV populations. From the mid-1990s to the mid-2000s, U.S. hospital admissions for diabetes rose 2.2-fold in people with HIV compared with 1.4-fold in HIV-negative people.3 Although studies disagree on whether HIV infection independently boosts chances of diabetes, this chronic disease clearly adds to myocardial infarction risk in people with HIV4,5 and can cause or contribute to kidney disease, liver disease, stroke, cognitive decline, and other HIV-linked maladies.
The retrospective diabetes-control studies took place at Chicago's CORE Center1 and New York's Weill Cornell Medical College,2 where HIV clinics care for thousands of patients yearly in a uniform, multidisciplinary manner and staffs have logged countless hours of experience caring for people with HIV. High proportions of HIV/diabetes patients at both centers were black or Hispanic, average age topped 50 years, and mean body mass index verged on the obesity threshold (Table 1). All study participants were adults with diabetes established by standard measures. Almost all took antiretrovirals and most had an undetectable viral load (Table 1).
|Table 1. Glycemic and Other Metabolic Targets Achieved in Two U.S. HIV Clinics|
|Chicago (n = 216)1||New York City (n = 142)2|
|Average body mass index (kg/m2)||28.3||28.7|
|Current smokers (%)||30*||25|
|Taking ART/undetectable VL (%)||98/72||92/56|
|HbA1c <7%/<8% (%)||54/72||57/78|
|Blood pressure <130/80 mm Hg (%)||56||42|
|Total cholesterol <200 mg/dL (%)||71||NR|
|LDL cholesterol <100 mg/dL (%)||56||66|
|HDL cholesterol >40/50† mg/dL (%)||51||32|
|Triglycerides <150 mg/dL (%)||39||31|
ART, antiretroviral therapy; HbA1c, hemoglobin A1c; HDL, high-density lipoprotein; LDL, low-density lipoprotein; NR, not reported.
* Smoking status not documented in 28%.
† HDL target >40 mg/dL in men, >50 mg/dL in women.
Both research teams calculated proportions of HIV diabetes patients who met two 2008 ADA goals for HbA1c -- below 7% or below 8%. (Current ADA guidelines suggest HbA1c goals ranging from below 6.5% to below 8%, depending on patient traits and risk of diabetes treatment side effects.6 Normal HbA1c lies below 5.7%.7)
For the general population, HbA1c is the main test used to manage and study diabetes.7 It measures attachment of glucose to hemoglobin in red blood cells. Because red cells live about 3 months, HbA1c determines a person's average blood glucose over the past few weeks to 3 months -- an advantage over the glucose snapshot with fasting glucose assays. Whether a person has fasted for 24 hours or just gobbled six glazed donuts has no impact on HbA1c-measured glucose, whereas a straight measure of glucose in blood requires fasting. Studies reviewed below indicate that HbA1c underestimates blood glucose in people with HIV. (See "Screening for high glucose" below for HbA1c use in people with HIV.) U.S. experts are divided on using HbA1c as a way to test HIV patients for diabetes.8-10
Proportions of HIV-positive diabetes patients who reached HbA1c targets proved similar in the two studies -- 54% in Chicago1 and 57% in New York2 below 7%; 72% in Chicago and 78% in New York under 8% (Table 1). Chicago did better in getting diabetes patients to hit a blood pressure goal below 130/80 mm Hg -- 56% versus 42% in New York. Chicago also had a much higher proportion of patients on target for HDL cholesterol (51% versus 32%), while both clinics struggled to guide patients toward a triglyceride tally below 150 mg/dL (39% and 31%). The New York group noted that only 47% of their patients had eye exams for retinopathy, and only 19% got screened for microalbuminuria.
Both research teams observed that HbA1c goal attainment in their HIV patients with diabetes mirrors or exceeds findings in the general population.1,2 Both teams also suggested their results may exceed those in broader U.S. HIV populations because they included only people with two or more clinic visits in 1 year (and thus possibly represented a more engaged population) and because both centers provide multidisciplinary teams with deep HIV experience.
Regardless of such variables, reaching a treatment goal in about half of patients might well be deemed failure. It is, for example, when the endpoint is proportion of patients with an undetectable HIV load. The Chicago and New York clinicians offer colleagues several suggestions for improving diabetes care in people with HIV (Table 2).
|Table 2. Strategies for Improving Diabetes Care in People With HIV1,2|
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