Detection of early nephropathy in Mexican patients with type 2 diabetes mellitus

Background. The aims of this study were to determine the prevalence of early nephropathy in patients with type 2 diabetes mellitus (DM2) attending primary care medical units and to identify risk factors for nephropathy in this population. Method. Seven hundred fifty-six patients with DM2 attending 3 primary care medical units were randomly selected. In a first interview, an albuminuria dipstick and a detailed clinical examination were performed, and a blood sample was obtained. If the albuminuria dipstick was positive, then a 24-hour urine collection was obtained within the next 2 weeks to quantify the albuminuria. In the blood sample, glucose, creatinine, and lipids were determined. Glomerular filtration rate was calculated using the Modification of Diet in Renal Disease Study equation. Demographics and medical history were recorded from clinical examination and medical charts. Results. Prevalence of early nephropathy (EN) was 40%, normal function (NF) was found in 31%, and overt nephropathy (ON) in 29%. Patients with more severe kidney damage were older (NF: 54 +/- 10; EN: 60 +/- 11; ON: 63 +/- 10 years, P < 0.05) and had a higher proportion of illiteracy (NF: 11%, EN: 17%; ON: 25%, P < 0.05). The more severe the nephropathy, the longer the median duration of DM2 (NF: 6.0; EN: 7.0; ON: 11.0 years; P < 0.05); the higher the frequency of hypertension (NF: 38%; EN: 52%; ON: 68%; P < 0.05); and the higher the systolic blood pressure (NF: 126 +/- 21; EN: 130 +/- 19; ON: 135 +/- 23 mm Hg; P < 0.05). Both nephropathy groups had a significantly higher proportion of family history of nephropathy (NF: 4%; EN: 9%; ON: 13%) and a higher frequency of cardiovascular disease (NF: 5%; EN: 12%; ON: 25%), whereas only patients with ON had peripheral neuropathy (NF: 21 %; EN: 22%; ON: 43%) and retinopathy (NF: 12%; EN: 18%; ON: 42%) more frequently than others. Fasting glucose was poorly controlled in all groups (NF: 186 +/- 70; EN: 173 +/- 62; ON: 183 +/- 73 mg/dL). Large body mass index (NF: 29.3 +/- 5.3; EN: 29.7 +/- 5.6; ON: 29.6 +/- 5.5 kg/m(2)), smoking (NF: 45%; EN: 43%; ON: 44%), and alcoholism (NF: 29%, EN: 29%; ON: 26%) were frequently found in this population, although there were no significant differences. In the multivariate analysis, only age, duration of DM2, and presence of retinopathy, hypertension, and cardiovascular disease were significantly associated with nephropathy. Conclusions. Two thirds of Mexican patients with DM2 attending primary health care medical units had nephropathy, 40% of whom were at an early stage of the disease. Many modifiable and nonmodifiable risk factors were present in these patients, but the most significant predictors for nephropathy are older age, longer duration of diabetes, and the presence of retinopathy, hypertension, and cardiovascular disease.