A 58-year-old man comes to the physician for follow-up of type 2 diabetes mellitus. He has had diabetes for 14 years. Other medical problems include hypertension and hyperlipidemia. His current medications include glipizide, metformin, lisinopril, atorvastatin, and daily low-dose aspirin. The patient's hemoglobin A1c has progressively increased over the last few years; however, he has repeatedly refused to add additional medication to improve glycemic control. He does not use tobacco or alcohol. The patient's father also had type 2 diabetes and died of a myocardial infarction at age 55. Blood pressure is 134/78 mm Hg and pulse is 78/min. BMI is 33 kg/m2. Physical examination, including lower extremity vascular and sensory examination, is normal. Laboratory evaluation shows a fasting blood glucose level of 178 mg/dL, serum creatinine of 1.1 mg/dL, and hemoglobin A1c of 8.8%. While discussing additional medication to improve his glycemic control, the patient says, "Doc, I feel fine. I don't understand why you keep trying to give me more pills." Which of the following is the most appropriate response to this patient?
| Effect of intensive glycemic control in type 2 diabetes | |
Macrovascular complications (eg, acute myocardial infarction, stroke) | No change (short-term) |
Microvascular complications (eg, nephropathy, retinopathy) | Improve |
Mortality | No change or increased |
There is general agreement that tight glycemic control can reduce the risk of microvascular complications of diabetes, especially nephropathy (eg, proteinuria, chronic kidney disease) and retinopathy. This effect has been observed in both type 1 and type 2 diabetes mellitus and is a primary factor behind the general recommendation that most patients with diabetes should have a target hemoglobin A1c of <7%.
In contrast, the benefits of glycemic control in preventing macrovascular complications and cardiovascular mortality (eg, myocardial infarction, stroke, peripheral arterial disease) have not been firmly established, and results from large prospective trials have been mixed (Choices A and D). The United Kingdom Prospective Diabetes Study enrolled recently-diagnosed subjects early in the course of the disease and noted a reduced risk of macrovascular complications on long-term follow up. However, studies that enrolled patients with long-standing diabetes (like this patient) did not see a reduced risk.
Taken together, current evidence suggests that tight glycemic control should generally be encouraged to reduce the risk of microvascular complications. However, efforts to prevent macrovascular events should focus on addressing other risk factors and include:
(Choice B) Diabetes mellitus with chronic hyperglycemia is associated with an increased risk of cognitive decline and dementia. However, the mechanism underlying this association is not clear, and studies on the effects of tight glycemic control have been mixed.
(Choice E) Major risk factors for abdominal aortic aneurysm include smoking, male sex, white ethnicity, advancing age, and hypertension. Diabetes mellitus may have a protective effect against the development of this condition.
Educational objective:
Tight glycemic control in patients with diabetes decreases the risk of microvascular complications (eg, retinopathy, nephropathy) but has an uncertain effect on macrovascular complications (eg, myocardial infarction, stroke).