Prevalence of type 2 diabetes among veterans is high, increasing, and likely to increase further due to increasing obesity. Type 2 diabetes increases risk of cardiovascular and microvascular diseases, causes of significant morbidity and mortality among veterans.
The objective was to determine whether time trends in risk factors predict cardiovascular and microvascular diseases independent of average levels of these risk factors in veterans with type 2 diabetes. We focused on cardiovascular and/or microvascular disease risk factors that are relatively inexpensive and commonly measured during standard clinical care.
In a longitudinal observational study that used data collected during standard clinical care of veterans enrolled at the Phoenix VA Health Care System, we used random-effects mixed models to characterize time trends and fluctuation of cardiovascular risk factors. We also used multivariable linear regression to assess relationships between risk factors and carotid intima-media thickness, a measure of atherosclerosis that predicts cardiovascular disease.
Analyses of data from 17,246 veterans aged 21 to 85 identified differences in weight according to sex (women 31.6 lb less than men, p<0.0001), race/ethnicity [Hispanic whites lighter than non Hispanic whites, p<0.0001). We also identified seasonal variation in weight: Weight was maximal (+1.4 lb, p<0.0001) on December 16 of each year. Baseline weight increased with each decade of age up to age 60 and declined thereafter (p<0.0001). However, 10-year weight changes estimated from these models were gains only up to age 40. Analyses of data for 471 subjects with impaired glucose tolerance, a precursor to type 2 diabetes, showed unadjusted values for carotid intimal-media thickness to increase in a stepwise fashion from lowest to highest tertile of maximal change in plasma glucose (DeltaG) during an oral glucose tolerance test (OGTT) (p for trend <0.02), but not across tertiles of fasting plasma glucose (FPG) or 2 hour glucose (2HrPG) during the OGTT. After adjusting for age, sex, race, ethnicity, BMI, current smoking, plasma triglyceride, total and HDL cholesterol, and systolic and diastolic blood pressure, FPG, 2HrPG, and insulin sensitivity, a 1 SD (23 mg/dL) increase in DeltaG during the OGTT was associated with a 20+8 um increase in carotid intima-media thickness (p< 0.02). In this model, FPG, 2hPG, and insulin sensitivity were not significantly related to carotid intima-media thickness.
These results suggest that the need for counceling on weight control is greatest for nonHispanic white men under age 40 and that need for such counseling is greatest in the fall/winter. Greater variation in plasma glucose during OGTT, reflecting impaired glucose metabolism, is likely to increase risk of cardiovascular disease. Targeting expensive screening, monitoring, and preventive efforts to persons with these clinical characteristics has the potential to improve patient health and prevent the need for expensive cardiovascular interventions.
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