Prospective Cohort Study

B - Click here for explanation of classification scheme.

POSITIVE: See Quality Criteria Checklist below.

• To evaluate the fat consumption of patients with newly diagnosed type II diabetes in Dutch general practice compared with reference values for the general population
• To evaluate alterations in fat consumption eight weeks after the initial diagnosis and referral to a dietitian according to the Dutch guidelines for treatment of type II diabetes
• To determine the fat consumption after four years of follow-up compared with initial consumption in these patients.

• Followed by one of 46 general practitioners working in 33 general practices throughout the Netherlands
• Newly diagnosed type II diabetes: Defined according to criteria established by the World Health Organization, including:
  • Symptoms suggestive of diabetes mellitus and a fasting blood glucose 6.7mmol per L or more and 20mmol per L
  • Asymptomatic newly diagnosed diabetes with fasting blood glucose higher than 6.7mmol per L on two or more occasions.
• Aged 40 years to 70 years
• Informed consent.

Recruitment

Recruited from 33 general practices throughout the Netherlands.

Design

• All patients were referred to a registered dietitian. Dietary intervention consisted of two consultation sessions with a four-week period in which patients received dietary advice concerning all aspects of medical nutrition therapy for diabetes, tailored to their individual needs. Dietitians were informed about baseline fat consumption in all patients but otherwise did not receive extra training or use of special protocols. Patients who still had fasting blood glucose 6.7mmol per L or more after eight weeks were eligible for oral anti-diabetic therapy. These patients were asked to participate in a 30-week randomized controlled trial comparing acarbose with tolbutamide.
• Measurements took place at diagnosis, after eight weeks and four years, and included dietary consumption evaluated with the use of a 104-item food frequency questionnaire, body weight and height, medical history, comorbidity, medication use, additional visits with dietitian or other sources of dietary information, serum glycosylated hemoglobin, serum lipids and serum glucose levels.

Intervention

Dietary intervention by registered dietitian.

Statistical Analysis

• Results given as mean ± standard deviation
• Student's two-sample T-tests performed for comparison between groups
• Student's one-sample test used for comparison of results between subsequent measurements
• Repeated measure analysis performed to assess an overall time effect
• T-test P<0.0024 and for repeated measure analysis P<0.0072 was considered significant.

 

Timing of Measurements

• All measurements were taken at diagnosis, after eight weeks and after four years:
  • Consumption of dietary fat measured with a 104-item food frequency questionnaire in which the past month was used as the reference period
  • Values for total energy, total fat, saturated fatty acids, monounsaturated fatty acids and cholesterol were calculated using a computer program and results from questionnaire
  • Body weight and height without shoes and with light clothing
  • Data on medical history, co-morbidity and the use of medications obtained from patients' records by their general practitioner
  • Information regarding any additional visits to a dietitian or use of other sources for dietary information was recorded with the help of short questionnaire
  • Glycosylated hemoglobin, glucose and lipids.
• At the four-year follow-up, GPs provided information about the use of anti-diabetic and cholesterol-lowering medication during the interval.

Dependent Variables

• Dietary fat consumption
• Total energy, total fat, saturated fatty acids, monounsaturated fatty acids and cholesterol intake.

Independent Variables

Dietary intervention consisting of two consultation sessions within a four-week period.

Control Variables

• Gender
• Age
• Body weight and height
• Medical history, co-morbidity and use of medications obtained from patients' records by their general practitioner
• Visits to dietitian or use of other sources for dietary information recorded with help of short questionnaire
• Glycosylated hemoglobin, glucose and lipids
• Blood pressure.

 

• Initial N: A total of 144 subjects (69 males, 75 females)
• Attrition (final N): 106 subjects
• Age: 57.8±8.3 years
• Other relevant demographics: Baseline results for patients who did not participate in the eight-week or four-year evaluation did not differ significantly from results of patients whose measurements were not missing
• Anthropometrics: BMI of 29.5±5.2kg/m²
• Location: Netherlands.

 

Key Findings

Fat consumption:

• Compared with reference figures for the general population, patients had a higher intake of energy and higher fat consumption
• At eight-week follow-up, there was a decrease in total energy intake, total fat, saturated fatty acids and monounsaturated fatty acids, while polyunsaturated fatty acids and relative cholesterol intake did not change
• At four-year follow-up, consumption of total fat and monounsaturated fatty acids increased significantly compared to eight weeks but remained significantly lower than baseline
• Repeated measure analysts showed similar results, with the exception that the difference in consumption of total fat between eight weeks and four years was not significant
• Male and female patients showed similar fat consumption at baseline except for energy and cholesterol intake, which were higher in males
• Women showed a more profound decrease in consumption of total fat, monounsaturated fatty acids and saturated fatty acids in both eight-week and four-year measurements
• The percentage of patients that met guideline regarding saturated fatty acids increased from 7.6% at baseline to 27.4% at the four-year measurement and the percentage of patients consuming less than 7% of energy intake from saturated fatty acids increased from 0.7% to 9.4%.

 

Variables	Change in Mean Difference Diagnosis to Eight Weeks: Mean (95% CI)	Change in Mean Difference Diagnosis to Four Years: Mean (95% CI)	Change in Mean Difference Eight Weeks to Four Years: Mean (95% CI)
Energy intake (MJ per day)	-2.2 (-2.6 to -1.7) P<0.0024	-1.8 (-2.3 to -1.2) P<0.0024	0.5 (0.09  to 0.9) Not significant
Total fat (percentage energy intake)	-5.1 (-6.6 to -3.5) P<0.0024	-3.0 (-4.8 to -1.2) P<0.0024	2.5 (1.1 to -3.9) P<0.0024
Saturated fatty acids (percentage energy intake)	-2.4 (-3.0 to -1.8) P<0.0024	-3.1 (-3.8 to -2.3) P<0.0024	-0.5 (-1.1  to 0.1) Not significant
Monounsaturated fatty acids (percentage energy intake)	-2.5 (-3.1 to -1.8) P<0.0024	-1.5 (-2.3 to -0.6) P<0.0024	1.0 (0.4 to -1.6) P<0.0024
Polyunsaturated fatty acids (percentage energy intake)	0.3 (-0.4 to -0.9) Not significant	0.9 (0  to 1.7) Not significant	0.9 (0  to 1.8) Not significant
Cholesterol intake (mg per day)	-63.1 (-77.8 to -48.3) P<0.0024	-99.7 (-120 to -79.4) P<0.0024	-33.6 (-48.3 to -18.8) P<0.0024
Cholesterol intake (mg per MJ)	-0.3 (-1.5 to -1.0) Not significant	-6.2 (-7.8 to -4.6) P<0.0024	-5.6 (-7.2 to -4.0) P<0.0024

Other Findings

People with BMI higher than 30kg/m² reported the lowest energy intake.

Plasma Lipids, Glycemic Control and Body Weight

• After eight weeks and two visits with a dietitian, 25.7% of patients had a fasting blood glucose less than 6.7mmol per L and hemoglobin A_1C decreased from 9.0% to 7.8%. All plasma lipid values except for HDL cholesterol and triglycerides improved at eight weeks
• After four years, hemoglobin A_1C and plasma lipids had significantly improved compared with baseline and, except for triglycerides, to the eight-week measurement
• BMI decreased at the eight-week measurement (P<0.01) but was back at baseline at the four-year measurement.

Diabetes Treatment

• At the four-year measurement, 18% of patients were still being treated with lifestyle modifications alone
• Use of cholesterol-lowering medications increased from 7% at baseline to 32% at the four-year follow-up
• After the first two visits with the dietitian, patients visited the dietitian 0.6±0.9 times per year
• A total of 77% of patients visited a dietitian less than once a year, 13% between one and two times a year and 10% had two or more consults a year.

Patients in general practice with type II diabetes had an unfavorable fat intake at time of diabetes diagnosis compared with reference values. Shortly after the first dietary consultation, fat consumption decreased to levels similar to general population. After four years, consumption of total fat increased but was still lower than baseline value, with increase due to higher intake of both polyunsaturated fatty acids and monounsaturated fatty acids. Cholesterol intake decreased at eight week and decreased further at four years.

Industry:

Dutch Dairy Foundation for Nutrition and Health, Bayer

• Authors provided a participant flow diagram to illustrate attrition
• No control group.