Person:

Conlin, Paul

Objective: Several studies have suggested that (HbA_{1c}) levels may predict incident diabetes. With new recommendations for use of (HbA_{1c}) in diagnosing diabetes, many patients with (HbA_{1c}) results below the diagnostic threshold will be identified. Clinicians will need to categorize risk for a subsequent diabetic diagnosis in such patients. The objective of this study was to determine the ability of (HbA_{1c}) to predict the incidence of a diabetic diagnosis. Research Design and Methods: We performed a historical cohort study using electronic medical record data from two Department of Veterans Affairs Medical Centers. Patients (n = 12,589) were identified with a baseline (HbA_{1c}) <6.5% between January 2000 and December 2001 and without a diagnosis of diabetes. Patients (12,375) had at least one subsequent follow-up visit. These patients were tracked for 8 years for a subsequent diagnosis of diabetes. Results: During an average follow-up of 4.4 years, 3,329 (26.9%) developed diabetes. (HbA_{1c}) (\geq)5.0% carried a significant risk for developing diabetes during follow-up. When compared with the reference group ((HbA_{1c}) <4.5%), (HbA_{1c}) increments of 0.5% between 5.0 and 6.4% had adjusted odds ratios of 1.70 (5.0–5.4%), 4.87 (5.5–5.9%), and 16.06 (6.0–6.4%) (P < 0.0001). Estimates of hazard ratios similarly showed significant increases for (HbA_{1c}) (\geq)5.0%. A risk model for incident diabetes within 5 years was developed and validated using (HbA_{1c}), age, BMI, and systolic blood pressure. Conclusions: The incidence of diabetes progressively and significantly increased among patients with an (HbA_{1c}) (\geq)5.0%, with substantially expanded risk for those with (HbA_{1c}) 6.0–6.4%.

Dietary studies designed to decrease the urinary albumin excretion rate (AER) typically reduce protein by increasing lower protein plant foods and decreasing higher protein animal products. STUDY DESIGN: We evaluated AER while increasing protein intake in the Dietary Approaches to Stop Hypertension (DASH) Trial (randomized, parallel group, 8 week controlled feeding). SETTING & PARTICIPANTS: 378 individuals without diabetes with prehypertension or stage I hypertension. INTERVENTION: The DASH diet, 18% energy from protein, emphasizes, among other features, low-fat dairy products; and the fruit/vegetable (FV) and control diets, each with 15% energy from protein. OUTCOME: AER. MEASUREMENTS: We measured AER by using immunoassay and covariates at baseline and after 8 weeks. RESULTS: Baseline AER had a geometric mean value of 4.0 +/- 0.2 (SE) mg/24 h. In 285 participants with baseline AER less than 7 mg/24 h, AER was unchanged by diet treatment (geometric mean, 2.5 +/- 0.2 mg/24 h in the control diet, 3.0 +/- 0.2 mg/24 h in the FV diet, and 2.8 +/- 0.2 mg/24 h in the DASH diet). Conversely, in 93 participants with baseline AER of 7 mg/24 h or greater, end-of-feeding AER was lower in the FV diet (6.6 +/- 1.0 mg/24 h) than in the control (11.4 +/- 1.8 mg/24 h; P = 0.01) or DASH diets (11.7 +/- 1.6 mg/24 h; P = 0.005). The DASH and control diets were not different (P = 0.9). LIMITATIONS: Long-term AER change not studied. CONCLUSIONS: The decrease in AER after 8 weeks occurred in only those with high-normal baseline AER in the FV diet, in a pattern distinct from the blood pressure decrease. The DASH diet did not increase AER despite a 3% increase in energy from protein.

Background: The effect of dietary composition on blood pressure is a subject of public health importance. We studied the effect of different levels of dietary sodium, in conjunction with the Dietary Approaches to Stop Hypertension (DASH) diet, which is rich in vegetables, fruits, and low-fat dairy products, in persons with and in those without hypertension.

Methods: A total of 412 participants were randomly assigned to eat either a control diet typical of intake in the United States or the DASH diet. Within the assigned diet, participants ate foods with high, intermediate, and low levels of sodium for 30 consecutive days each, in random order.

Results: Reducing the sodium intake from the high to the intermediate level reduced the systolic blood pressure by 2.1 mm Hg (P<0.001) during the control diet and by 1.3 mm Hg (P=0.03) during the DASH diet. Reducing the sodium intake from the intermediate to the low level caused additional reductions of 4.6 mm Hg during the control diet (P<0.001) and 1.7 mm Hg during the DASH diet (P<0.01). The effects of sodium were observed in participants with and in those without hypertension, blacks and those of other races, and women and men. The DASH diet was associated with a significantly lower systolic blood pressure at each sodium level; and the difference was greater with high sodium levels than with low ones. As compared with the control diet with a high sodium level, the DASH diet with a low sodium level led to a mean systolic blood pressure that was 7.1 mm Hg lower in participants without hypertension, and 11.5 mm Hg lower in participants with hypertension.

Conclusions: The reduction of sodium intake to levels below the current recommendation of 100 mmol per day and the DASH diet both lower blood pressure substantially, with greater effects in combination than singly. Long-term health benefits will depend on the ability of people to make long-lasting dietary changes and the increased availability of lower-sodium foods.