Type 1
diabetes
Setting individual patient glycemic targets should take
into account the results of prospective randomized clinical trials,
most notably the Diabetes Control and Complications Trial (DCCT). This
trial conclusively demonstrated that in patients with type 1 diabetes
the risk of development or progression of retinopathy, nephropathy,
and neuropathy is reduced 50-75% by intensive treatment regimens when
compared with conventional treatment regimens. These benefits were observed
with an average HbA1c of 7.2% in intensively treated groups of patients
compared with 9.0% in conventionally treated groups of patients. The
reduction in risk of these complications correlated continuously with
the reduction in HbA1c produced by intensive treatment. This relationship
implies that near normalization of glycemic levels may prevent complications.
The nondiabetic reference range for the HbA1c in the DCCT was 4.0-6.0%.
Self Monitoring
of Blood Glucose (SMBG) targets in the DCCT were 70-120 mg/dl (3.9-6.7
mmol/l) before meals and at bedtime and <180 mg/dl (<10.0 mmol/l) when
measured 1.5-2.0 h postprandially. However, these goals were associated
with a threefold increased risk of severe hypoglycemia. Therefore, it
may be appropriate to increase these targets (e.g., 80-120 mg/dl [4.4-6.7
mmol/l] before meals and 100-140 mg/dl [5.6-7.8 mmol/l] at bedtime).
These targets should be further adjusted upward in patients with a history
of recurrent, severe, or unrecognized hypoglycemia.
Type 2 diabetes
The largest and longest study of patients with type 2
diabetes, the United Kingdom Prospective Diabetes Study (UKPDS), conclusively
demonstrated that improved blood glucose control in these patients reduces
the risk of developing retinopathy and nephropathy and possibly reduces
neuropathy. The overall microvascular complications rate was decreased
by 25% in patients receiving intensive therapy versus conventional therapy.
Epidemiological analysis of the UKPDS data showed a continuous relationship
between the risk of microvascular complications and glycemia, such that
for every percentage point decrease in HbA1c (e.g., 9 to 8%) there was
a 35% reduction in the risk of microvascular complications. These results
confirm in type 2 diabetes that lowering blood glucose is beneficial.
The UKPDS also showed that aggressive control of blood pressure, consistent
with American Diabetes Association recommendations, significantly reduced
strokes, diabetes-related deaths, heart failure, microvascular complications,
and visual loss.
Type 2 diabetes
treatment methods should emphasize diabetes management as a multiple
factor approach including Medical Nutrition Therapy (MNT), exercise,
weight reduction when indicated, and use of oral glucose-lowering agents
and/or insulin, with careful attention given to cardiovascular risk
factors, including hypertension, smoking, dyslipidemia, and family history.
