Top POEMs of 2012: Diabetes Mellitus

Benefits Lacking for Tight Control of Type 2 Diabetes

Clinical question: Does aiming for lower blood glucose values provide a benefit to patients with type 2 diabetes, as compared with less intensive treatment?

Bottom line: With good confidence, based on long-term trials, we can say that intensive control of blood glucose does not lengthen life or decrease nephropathy risk, but doubles the occurrence of hypoglycemia severe enough to warrant intervention. The risks of myocardial infarction, a composite of microvascular outcomes, and retinopathy are decreased with intensive control, but the information size was not sufficient to confirm these benefits. Cardiovascular mortality is not decreased, but this result may change with future study. (LOE = 1a)

Reference: Hemmingsen B, Lund SS, Gluud C, et al. Intensive glycaemic control for patients with type 2 diabetes: systematic review with meta-analysis and trial sequential analysis of randomised clinical trials. BMJ 2011;343:d6898.

Study design: Meta-analysis (randomized controlled trials)

Funding source: Foundation

Setting: Various (meta-analysis)

Synopsis: The Danish investigators performing this meta-analysis for the Cochrane Collaboration searched several databases, including the Cochrane Library, along with abstracts presented at meetings, reference lists of identified studies, and pharmaceutical companies. Their goal was to find all studies comparing the effect of targeting intensive glycemic control, regardless of the actual level of control or the percentage of time it was achieved. Two authors screened the studies for inclusion and quality, and independently extracted the data according to the usual Cochrane rules. Using a relatively new method called "trial sequential analysis," they were able to determine whether there was sufficient "information size" to confidently detect or reject a 10% relative risk reduction in pertinent outcomes. Their analysis included 14 clinical trials enrolling a total of 28,614 patients. They found a sufficient information size to conclude that, as compared with less intense control of glycemia, intensive control did not affect all-cause mortality. Cardiovascular mortality was not reduced, but the information size was not sufficient to absolutely reject a benefit. The risk of myocardial infarction, a composite of microvascular outcomes, and retinopathy were decreased, but the information size was not sufficient to confirm this benefit. Nephropathy was not decreased with intensive control. The risk of severe hypoglycemia was significantly increased in patients attempting intensive control and was more than twice as likely than with less intense control (relative risk = 2.39; 95% CI, 1.71 - 3.34).

Allen F. Shaughnessy, PharmD, MMedEd
Professor of Family Medicine
Tufts University
Boston, MA

Tight Glycemic Control in Elderly with DM Decreases Function

Clinical question: Do community dwelling but functionally impaired elderly patients with tightly controlled diabetes do better than those with less tightly controlled diabetes?

Bottom line: Community-dwelling elderly patients with tightly controlled diabetes are at greater risk of functional decline than those with modestly controlled disease. Although this is not a randomized trial, the findings are consistent with other clinical trials showing that tight glycemic control in adults with diabetes does not improve outcomes. (LOE = 1b-)

Reference: Yau CK, Eng C, Cenzer IS, John Boscardin W, Rice-Trumble K, Lee SJ. Glycosylated hemoglobin and functional decline in community-dwelling nursing home-eligible elderly adults with diabetes mellitus. J Am Geriatr Soc 2012;60(7):1215-1221.

Study design: Cohort (prospective)

Funding source: Government

Setting: Population-based

Synopsis: These researchers tested the hypothesis that better glycemic control (hemoglobin A1C [Hb A1C] = 8.0% or lower) would be associated with less functional decline in 357 community-dwelling elders with diabetes and with functional or cognitive impairments that would make them nursing home eligible. The researchers evaluated participants every 6 months for 2 years. They compared the baseline Hb A1C levels with changes in measures of functional status during the 2-year follow up and tried to take into account other factors that might influence function or cognition (eg, age, duration of disability, use of insulin, and so forth). During the study period, nearly two thirds of the patients experienced functional decline and approximately one third died. Taking into account other factors that might influence function or death, patients with Hb A1C levels higher than 8% had a slightly lower risk of deterioration than patients with Hb A1C levels of less than 8% (relative risk = 0.88; 95% CI, 0.79 - 0.99). This cohort study found a relatively weak association between glycemic control and function. Cohort studies are better at generating questions about treatment effect than they are at answering them. Nonetheless, the findings are consistent with clinical trial data that fail to show clinical improvement in patients with aggressively treated diabetes.

Henry C. Barry, MD, MS
Professor
Michigan State University
East Lansing, MI

Home Glucose Monitoring Does Not Affect Control in Diabetes

Clinical question: Does home monitoring of blood glucose levels result in better management of patients with type 2 diabetes not treated with insulin?

Bottom line: Home glucose monitoring does not appreciably improve control in patients with type 2 diabetes not treated with insulin, lowering glycated hemoglobin (Hb A1c) an average 0.25 percentage points (eg, from 8.3% to 8.05%) after 6 months or 12 months of use. There does not seem to be a subgroup of patients for whom it works better. Save the gizmos for patients who use insulin so they can monitor themselves for hypoglycemia. (LOE = 1a)

Reference: Farmer AJ, Perera R, Ward A, et al. Meta-analysis of individual patient data in randomised trials of self-monitoring of blood glucose in people with non-insulin treated type 2 diabetes. BMJ 2012;344:e486.

Study design: Meta-analysis (randomized controlled trials)

Funding source: Foundation

Setting: Various (meta-analysis)

Synopsis: The authors assembled randomized controlled trials comparing management using home glucose-monitoring machines with management not using self-monitoring in patients with noninsulin-treated diabetes. They identified the studies by searching bibliographies of recent other systematic reviews, as well as 2 databases and the controlled trials registry. After excluding small or short-duration trials, the authors solicited individual patient data from researchers conducting the 6 included trials (N = 2552). Their analysis was by intention to treat and treatment allocation was concealed until the end of the analysis. The average age of patients in the studies was 60.1 years with a median duration of diabetes of 3 years. Baseline Hb A1c was 8.3% (67.0 mmol/mol). Self-monitoring resulted in a statistically lower Hb A1c level after 6 months, though the difference was an average of 0.25 percentage points (2.7 mmol/mol). The difference in average Hb A1c was similar at 12 months. Age, baseline Hb A1c level, sex, and duration of diabetes did not affect the results.

Allen F. Shaughnessy, PharmD, MMedEd
Professor of Family Medicine
Tufts University
Boston, MA

POEMs are provided by Essential Evidence Plus, a point-of-care clinical decision support system published by Wiley-Blackwell. For more information, please see http://www.essentialevidenceplus.com(www.essentialevidenceplus.com).

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